Re: OT Firemen unable to tackle fire effectively due to solar panels on roof

[Man at B&Q]

On May 8, 8:33 am, Chris Hogg <m...@privacy.net> wrote:
> http://www.bbc.co.uk/news/uk-england-devon-22439099
>
> John Chalk from the fire service said: "There were solar panels on the
> roof which meant in effect we still had a live supply of electricity
> to the building, so we weren't able to get into the building.

What was stopping them, FFS? how do thay manage in any other building,
without solar panels, such as a house where the main fuse and isolator
are in the house?

"A fire service spokesman said an investigation into the cause of the
blaze would begin on Wednesday." I hope that's followed by an
investigation into the behaviour of the fire service.

MBQ

[Nick Odell]

Perhaps they thought that the panels run at 230v AC or maybe there are
some other factors not mentioned in the report - such as a petrol
generator suspended from the ceiling.
(http://www.bbc.co.uk/news/uk-scotland-tayside-central-21770421)

Hopefully there will be more information later.

Nick

[RobertL]

On Wednesday, May 8, 2013 11:26:40 AM UTC+1, Nick Odell wrote:
> On Wed, 8 May 2013 02:30:57 -0700 (PDT), "Man at B&Q"

> <manat...@hotmail.com> wrote:

>
> >> John Chalk from the fire service said: "There were solar panels on the
> >> roof which meant in effect we still had a live supply of electricity
> >> to the building, so we weren't able to get into the building.

> Perhaps they thought that the panels run at 230v AC

Don't these PV panel arrays run at 100+ Volts DC which would be more dangerous to a fireman than an AC power supply.

Robert

[newshound]

Normally, there is a readily accessible isolator for the incoming mains
right by the front door. I suppose their concern is that the panels
could be charging batteries connected to an inverter in the attic or
somewhere otherwise inaccessible (particularly if it was DIY'd).

So while I half agree that it seems a slightly "wussy" statement from
the fireman I can also half see his point. And it would have been the
local guy in charge who would have been in the dock if one of the
firemen had got zapped.

[dennis@home]

On 08/05/2013 11:26, Nick Odell wrote:

The panels run at about 40V DC and are daisy chained to give upto about
700V DC.

The DC runs in extra thick insulated cable to the inverter that makes it
230V AC.
The AC side will shut down as soon as grid power is lost.
The DC side will then rise about 10% in voltage as no current is being
drawn.

I can't see any real extra danger for the fire fighters as the DC side
tends to be in weather proof connectors and it doesn't matter if they
get wet.

[Dave Liquorice]

On Wed, 08 May 2013 12:11:19 +0100, newshound wrote:

> Normally, there is a readily accessible isolator for the incoming mains
> right by the front door.

Some commercial places have external "Firemans Switches" not sure what
they do but one would assume they are in the supply before any
distribution. Domestic well, there are 3 lots of CU's here only one is
"by the front door". The other two are in a windowless room in the middle
of the building.

I also wonder how much affect having the entire roof covered in panels
stopped them breaking into the roof from outside and kept the water out
where the fire had broken through as well...

> So while I half agree that it seems a slightly "wussy" statement from
> the fireman I can also half see his point. And it would have been the
> local guy in charge who would have been in the dock if one of the
> firemen had got zapped.

The Fire Service do come up with some "odd" reasons for not doing what
one would expect based on Health & Safety of the firemen at times.

--
Cheers
Dave.

[Brian Gaff]

I was under the impression that the invertors was wired in such a way that
if the main switch was off it stopped as well. To work any other way would
be downright dangerous in myy view. the panels themselves generate low
voltages so should be disregarded.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: bri...@blueyonder.co.uk
______________________________________________________________________________________________________________


"Chris Hogg" <m...@privacy.net> wrote in message
news:5nvjo8haeb899k21i...@4ax.com...

> http://www.bbc.co.uk/news/uk-england-devon-22439099
>
> John Chalk from the fire service said: "There were solar panels on the
> roof which meant in effect we still had a live supply of electricity

> to the building, so we weren't able to get into the building. It meant
> the fire developed much more rapidly than we would have liked."
>
> One wonders if an electrical fault in the solar panel wiring actually
> caused the fire in the first place.
>
> --
>
> Chris

[Brian Gaff]

Or at least a clarification of any risks that may be present.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: bri...@blueyonder.co.uk
______________________________________________________________________________________________________________

"Man at B&Q" <manat...@hotmail.com> wrote in message
news:bb37f2fa-6b33-48ef...@oy9g2000pbb.googlegroups.com...

[Man at B&Q]

On May 8, 2:50 pm, "Brian Gaff" <Bria...@blueyonder.co.uk> wrote:
> I was under the impression that the invertors was wired in such a way that
> if the main switch was off it stopped as well. To work any other way would
> be downright dangerous in myy view. the panels themselves generate low
> voltages so should be disregarded.

If the external mains fails then inverters *have to* shutdown,
otherwise they will power a "power island" which will be potentially
fatal to anyone investigating the supposedly dead mains.

MBQ

[Martin Brown]

On 08/05/2013 14:51, Brian Gaff wrote:

> Or at least a clarification of any risks that may be present.
>
> Brian
>

I have known the fire brigade let an entire lab block burn down because
there was sodium metal in the lab. We worked out that there was about
100g at most, but that small misunderstanding caused severe devastation.

I think they have reported before that they are wary of fires in the
roof space of buildings with solar panels because the panel side stays
seriously hot as in hundreds of volts DC when open circuit in sunlight.
High voltage and moderate current is more efficient but has its
drawbacks if the cables insulation gets compromised in a fire.

Contact with such high DC voltages would definitely spoil your day.

The inverters should always shut down when mains is not present.

--
Regards,
Martin Brown

[newshound]

Interesting.

So what's the fix? Spray a blanket of foam over the panels before doing
anything else, at least in daytime?

Use high pressure hoses to disrupt the panels first?

Require a fire-resistant engineered device to "crowbar" the panels when
tripped manually or by fire? That's the sort of thing which gets imposed
on nuclear power plant (we call it defence in depth).

[The Natural Philosopher]

On 08/05/13 15:42, Jethro_uk wrote:

> Is the upshot of this that houses with solar panels will end up paying
> increased insurance premiums ?
WE can but hope so :-)


--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

[Dave Liquorice]

On Wed, 8 May 2013 14:50:21 +0100, Brian Gaff wrote:

> I was under the impression that the invertors was wired in such a way
> that if the main switch was off it stopped as well. To work any other
> way would be downright dangerous in myy view.

Yep without incoming mains the invertor shuts down, but if the sun is
shining on the panels they don't shut down...

> the panels themselves generate low voltages so should be disregarded.

Er, no several hundred volts DC with a fair bit of energy behind 'em.

Think about it. Take a normal 4 kWp "domestic" array say at 50 V that
would require 80 A, not impossible to handle but I^2R losses in cables or
joints become significant. Make the panels 500V DC (which they are ish)
and it drops to a much easier to handle 8 A.

That hotel looked to have some what larger tah 4 kWp array...

--
Cheers
Dave.

[Nightjar]

On 08/05/2013 14:22, Dave Liquorice wrote:
> On Wed, 08 May 2013 12:11:19 +0100, newshound wrote:
>
>> Normally, there is a readily accessible isolator for the incoming mains
>> right by the front door.
>
> Some commercial places have external "Firemans Switches" not sure what

> they do ...

They are usually there to disconnect neon signs.

Colin Bignell

[polygonum]

On 08/05/2013 16:13, The Natural Philosopher wrote:
> On 08/05/13 15:42, Jethro_uk wrote:
>> On Wed, 08 May 2013 15:22:11 +0100, Martin Brown wrote:
>>
>>> On 08/05/2013 14:51, Brian Gaff wrote:
>>>
>>>> Or at least a clarification of any risks that may be present.
>>>>
>>>> Brian
>>>>
>>>>
>>> I have known the fire brigade let an entire lab block burn down because
>>> there was sodium metal in the lab. We worked out that there was about
>>> 100g at most, but that small misunderstanding caused severe devastation.
>>>
>>> I think they have reported before that they are wary of fires in the
>>> roof space of buildings with solar panels because the panel side stays
>>> seriously hot as in hundreds of volts DC when open circuit in sunlight.
>>> High voltage and moderate current is more efficient but has its
>>> drawbacks if the cables insulation gets compromised in a fire.
>>>
>>> Contact with such high DC voltages would definitely spoil your day.
>>>
>>> The inverters should always shut down when mains is not present.
>> Is the upshot of this that houses with solar panels will end up paying
>> increased insurance premiums ?
> WE can but hope so :-)
>
>

That would be FITting.

--
Rod

[Dave Liquorice]

On Wed, 08 May 2013 16:21:13 +0100, Nightjar wrote:

>> Some commercial places have external "Firemans Switches" not sure what
>> they do ...
>
> They are usually there to disconnect neon signs.

I've seen on places that don't have neon signs... One for Adam.

--
Cheers
Dave.

[Martin Brown]

On 08/05/2013 15:41, Jethro_uk wrote:

> Does anyone remember a few years ago a fire brigade spokesman attracting
> a lot of ridicule when he said that unleaded petrol was for some reason
> more dangerous than leaded ?

I suppose it depends how you measure "danger".

Leaded is a lot more acutely toxic with its tetra-ethyl lead antiknock
but unleaded has a higher content of benzene and MTBE which makes it a
potential carcinogenic hazard in the longer term.

Either will be equally unforgiving and nasty in a fire.

--
Regards,
Martin Brown

[harry]

They could be running at up to 1000 volts. DC
Mine run at up to 750 volts. But only when the sun shines.
But they can't be turned off except by covering them.

[John Williamson]

When I was working at a filling station a long time ago, I was told that
the fireman's switch cut power to the whole of the forecourt. So, pumps,
lights and any other stuff outside the main building. Basically,
anything that could cause a spark in the area of the pumps.

--
Tciao for Now!

John.

[harry]

On May 8, 2:50 pm, "Brian Gaff" <Bria...@blueyonder.co.uk> wrote:

> I was under the impression that the invertors was wired in such a way that
> if the main switch was off it stopped as well. To work any other way would
> be downright dangerous in myy view. the panels themselves generate low
> voltages so should be disregarded.
>
>  Brian
>
> --
> Brian Gaff....Note, this account does not accept Bcc: email.
>  graphics are great, but the blind can't hear them

> Email: bria...@blueyonder.co.uk
> ___________________________________________________________________________ ___________________________________

>
> "Chris Hogg" <m...@privacy.net> wrote in message
>
> news:5nvjo8haeb899k21i...@4ax.com...
>
>
>
>
>
>
>
> >http://www.bbc.co.uk/news/uk-england-devon-22439099
>
> > John Chalk from the fire service said: "There were solar panels on the
> > roof which meant in effect we still had a live supply of electricity
> > to the building, so we weren't able to get into the building. It meant
> > the fire developed much more rapidly than we would have liked."
>
> > One wonders if an electrical fault in the solar panel wiring actually
> > caused the fire in the first place.
>
> > --
>
> > Chris

The panels always generate in sunlight. You can isolate them
but not shut them down.

[ARW]

Would it surprise you that pub beer cellars seem to have more stringent
electrical regs than a petrol station?


--
Adam

[polygonum]

Never seen a beer cellar at a petrol station...

Oh! I see what you mean. :-)

--
Rod

[Mr Pounder]

"ARW" <adamwa...@blueyonder.co.uk> wrote in message
news:kme4jg$8a4$1...@dont-email.me...

Yes.
Tell me about it.

[Martin Brown]

On 08/05/2013 15:34, newshound wrote:
> On 08/05/2013 15:22, Martin Brown wrote:
>> On 08/05/2013 14:51, Brian Gaff wrote:
>>
>>> Or at least a clarification of any risks that may be present.
>>>
>>> Brian
>>>
>>
>> I have known the fire brigade let an entire lab block burn down because
>> there was sodium metal in the lab. We worked out that there was about
>> 100g at most, but that small misunderstanding caused severe devastation.
>>
>> I think they have reported before that they are wary of fires in the
>> roof space of buildings with solar panels because the panel side stays
>> seriously hot as in hundreds of volts DC when open circuit in sunlight.
>> High voltage and moderate current is more efficient but has its
>> drawbacks if the cables insulation gets compromised in a fire.
>>
>> Contact with such high DC voltages would definitely spoil your day.
>>
>> The inverters should always shut down when mains is not present.
>>
>
> Interesting.
>
> So what's the fix? Spray a blanket of foam over the panels before doing
> anything else, at least in daytime?
>
> Use high pressure hoses to disrupt the panels first?

Dunno. I'd want some kind of isolator. Water and electricity don't mix!

>
> Require a fire-resistant engineered device to "crowbar" the panels when
> tripped manually or by fire? That's the sort of thing which gets imposed
> on nuclear power plant (we call it defence in depth).

That or a Woods metal fuse that melts and breaks the circuit if it gets
too hot. A single panel on its own doesn't pose any threat apart from
mechanical as a slip/trip hazard or if it falls off the roof.

I believe they have analysed the potential risks in detail but I don't
know what they concluded. Much of what is out on the web is specific to
US building codes and being wooden they go up like matchwood!

http://energy.edu.pl/oil-6344.html

--
Regards,
Martin Brown

[The Natural Philosopher]

I am fairly sure a sledeghammer would turn them off..

[PeterC]

On Wed, 8 May 2013 09:42:55 -0700 (PDT), harry wrote:

> The panels always generate in sunlight. You can isolate them
> but not shut them down.

Nowadays the firemen need some way of dealing with this problem - I wonder
if spraying with a thick layer of foam would work.
--
Peter.
The gods will stay away
whilst religions hold sway

[polygonum]

And might cause a bit of broken glass...

Hot topic: lessons on reacting to a solar panel fire
By Greg Spanoudakis
|
10 April 2012

"One simple first step is to inform the local fire department that your
building has been fitted with solar modules. Often, firefighters only
learn that the building is equipped with a solar system when they arrive
on the scene. This is a problem because solar rooftop installations
demand a different approach both in terms of safety and because
traditional extinguishing methods do not apply to electrical systems.
Not only does the rooftop position, risk of falling glass and slippery
surfaces of the modules need to be considered, but so too does the
system’s high DC voltage."

http://www.solarpowerportal.co.uk/guest_blog/hot_topic_lessons_on_reacting_to_a_solar_panel_fire_5478

Has everyone here with solar panels informed their local fire people?
What would the fire people do with the information?

--
Rod

[Tim+]

polygonum <rmoud...@vrod.co.uk> wrote:
>
>
> "One simple first step is to inform the local fire department that your
> building has been fitted with solar modules. Often, firefighters only
> learn that the building is equipped with a solar system when they arrive
> on the scene. This is a problem because solar rooftop installations
> demand a different approach both in terms of safety and because
> traditional extinguishing methods do not apply to electrical systems. Not
> only does the rooftop position, risk of falling glass and slippery
> surfaces of the modules need to be considered, but so too does the
> system’s high DC voltage."
>
> http://www.solarpowerportal.co.uk/guest_blog/hot_topic_lessons_on_reacting_to_a_solar_panel_fire_5478
>
> Has everyone here with solar panels informed their local fire people?
> What would the fire people do with the information?

Put you on the fireman's equivalent of the "do not resuscitate" list? ;-)

Tim

[Andy Champ]

On 08/05/2013 15:34, newshound wrote:

> So what's the fix? Spray a blanket of foam over the panels before doing
> anything else, at least in daytime?

At first sight, I thought don't be silly.

But on second thoughts - do you mean really opaque, sticky foam? That
would leave the panels in darkness?

Andy

[polygonum]

With the dangers involved, I wouldn't blame them. Sounds a bit like
using a defib without shouting "Clear!".

--
Rod

[newshound]

I was originally assuming that the sort of stuff they spray on crashed
planes would do the job but, on reflection, although it would catch all
the IR it would probably still let perhaps half of the shorter
wavelengths through. I expect Martin will be along in a minute with a
definitive answer.

[Andrew Gabriel]

In article <fpSdnVPL1Nzz8BfM...@giganews.com>,

and they're not rated for 1000V DC.

There are solar panel versions with remote switching
http://www.eaton-solar.com/en/safety/index.phtml
but I don't know if UK fire authorities will recognised them.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

[harry]

They still work with a thin layer of snow.
A thick layer of snow shuts them down.

[harry]

On May 8, 10:10 pm, and...@cucumber.demon.co.uk (Andrew Gabriel)
wrote:
> In article <fpSdnVPL1Nzz8BfMnZ2dnUVZ_uqdn...@giganews.com>,

>         Nightjar <c...@insert.my.surname.here.me.uk> writes:
>
> > On 08/05/2013 14:22, Dave Liquorice wrote:
> >> On Wed, 08 May 2013 12:11:19 +0100, newshound wrote:
>
> >>> Normally, there is a readily accessible isolator for the incoming mains
> >>> right by the front door.
>
> >> Some commercial places have external "Firemans Switches" not sure what
> >> they do ...
>
> > They are usually there to disconnect neon signs.
>
> and they're not rated for 1000V DC.
>

> There are solar panel versions with remote switchinghttp://www.eaton-solar.com/en/safety/index.phtml

> but I don't know if UK fire authorities will recognised them.
>

The idea put forward at the link is drivel. The panels are still
generating however isolated.

A slight danger arises if water is sprayed on them of electrocution.
The danger is slight because they are weather/waterproof as is all the
wiring and connections.
This would only be damaged if the roof was already seriously on fire.

There are no other hazards. Certainly nothing to stop them entering a
building. If they shut off the main electric supply, the inverter
would shut down.
The wiring from the panels to the inverter would still be live in
daylight. There might be a case for using say MICC cable for this
wiring.

The only other thing that could be done is to break up the "chain" of
panels. The individual panels only run at 30 or 40 volts.

[harry]

On May 8, 10:10 pm, and...@cucumber.demon.co.uk (Andrew Gabriel)
wrote:

> In article <fpSdnVPL1Nzz8BfMnZ2dnUVZ_uqdn...@giganews.com>,

>         Nightjar <c...@insert.my.surname.here.me.uk> writes:
>
> > On 08/05/2013 14:22, Dave Liquorice wrote:
> >> On Wed, 08 May 2013 12:11:19 +0100, newshound wrote:
>
> >>> Normally, there is a readily accessible isolator for the incoming mains
> >>> right by the front door.
>
> >> Some commercial places have external "Firemans Switches" not sure what
> >> they do ...
>
> > They are usually there to disconnect neon signs.
>
> and they're not rated for 1000V DC.
>

> There are solar panel versions with remote switchinghttp://www.eaton-solar.com/en/safety/index.phtml

> but I don't know if UK fire authorities will recognised them.
>
> --
> Andrew Gabriel
> [email address is not usable -- followup in the newsgroup]

Just looked at the video on that link.
Absolute drivel. But American, what do you expect?

All solar panel in the UK are already fitted with an isolator.
But it doesn't cure the problem discussed here.

[Andrew Gabriel]

In article <11pg9gpq5m6sb$.1i86pvszb6xq6$.d...@40tude.net>,

PeterC <giraffe...@homecall.co.uk> writes:
> On Wed, 8 May 2013 09:42:55 -0700 (PDT), harry wrote:
>
>> The panels always generate in sunlight. You can isolate them
>> but not shut them down.
>
> Nowadays the firemen need some way of dealing with this problem - I wonder
> if spraying with a thick layer of foam would work.

It should not be impossible to come up with a suitable product.
A foam with an opaque black dye and something to make it stick
to inclined self-cleaning glass and stay there in a fire, and
nothing flammable in the propellent or foaming agent.

The trouble may be that application of such a product may render
the house beyond viable repair, in which case it may not save
much over letting it burn to the ground as seems to be the norm
around the world for solar panel homes at the moment, after
rescuing anyone inside.

When I was holidaying around south of France in 1970's, I saw
3 solar furnaces, the two larger ones being hillsides covered in
large moving mirror arrays which focused the sun on a point to
generate lots of heat, which was used in various ways to generate
electricity (or just to melt things for fun, such as car engine
blocks). When I first saw the mirrors, my thought was, what do
they do if the mirror array loses power and can't keep the sun
focused on the right spot? When I saw the target, it became
obvious there was no such protection - burn lines all over the
concrete around it where the mirror array had obviously got
stuck and the sun's focus moved off target. I thought at the
time a simple drop-down roller blind at the top of each mirror
would solve that problem. The same goes for solar panels.

Another option might be to short out the solar panels in an
emergency so there is no high voltage (just high current).
However, a number of existing installations have caught fire
due to the connection resistances in the junction boxes at
nornal operating current, and that is very much more likely
to happen when the array is shorted out.

[Ian Jackson]

In message <kme4jg$8a4$1...@dont-email.me>, ARW
<adamwa...@blueyonder.co.uk> writes

Is that why beer's more than twice as expensive as petrol?
--
Ian

[Man at B&Q]

*very* sticky foam, preferrably.

MBQ

[Nightjar]

On 08/05/2013 21:21, PeterC wrote:
> On Wed, 8 May 2013 09:42:55 -0700 (PDT), harry wrote:
>
>> The panels always generate in sunlight. You can isolate them
>> but not shut them down.
>

> Nowadays the firemen need some way of dealing with this problem...

It seems they have - evacuate everybody and try to contain the fire
while it burns itself out.

Colin Bignell

[Andy Burns]

PeterC wrote:

> On Wed, 8 May 2013 09:42:55 -0700 (PDT), harry wrote:
>
>> The panels always generate in sunlight. You can isolate them
>> but not shut them down.
>
> Nowadays the firemen need some way of dealing with this problem

I checked the standard operating procedures of a local fire service,
their documents for dealing with fires in buildings and fires involving
electricity were update a few years ago to take account solar panels.

In short ... make sure all personnel know that solar panels present,
they and their wiring may remain live even after isolation (possibly
under moonlight, or emergency scene lighting) so don't touch, they might
fall or result in broken glass so don't work under them, there's a small
risk they might give of nasty fumes so wear breathing apparatus anyway.

Nothing to say avoid tackling the fire because of them.

[dennis@home]

On 09/05/2013 19:15, Chris Hogg wrote:

> On Wed, 08 May 2013 08:33:47 +0100, Chris Hogg <m...@privacy.net> wrote:
>
>> http://www.bbc.co.uk/news/uk-england-devon-22439099
>>
>> John Chalk from the fire service said: "There were solar panels on the
>> roof which meant in effect we still had a live supply of electricity

>> to the building, so we weren't able to get into the building. It meant
>> the fire developed much more rapidly than we would have liked."
>>
>> One wonders if an electrical fault in the solar panel wiring actually
>> caused the fire in the first place.
>

> The item came up on our local BBC TV this evening. Apparently it's
> guidance issued by Devon&Somerset Fire and Rescue Authority, as
> opposed to an on-the-spot decision by the fire officer in charge.
> They're worried that the fire crew may be electrocuted when hoses are
> sprayed onto the panels or exposed wiring. The makers of the solar
> panels say it can't happen.
>

So what's the big electrical different between the water from the hoses
and rain?
Solar panels sit in all sorts of weather and nobody gets electrocuted
because they are wet.

[polygonum]

Not a lot. But...

Cold water onto hot glass might break it.
Water sprayed upwards at high pressure might get to parts rain doesn't
reach.
Fire might already have damaged the panels.
With rain there is no potentially conductive stream of water from a
person to the panel.

And probably dozens of other differences.

--
Rod

[tony sayer]

In article <518beede$0$15365$c3e8da3$9f40...@news.astraweb.com>,
dennis@home <den...@killspam.kicks-ass.net> scribeth thus

Stunning knowledge of the leccy den;!...
--
Tony Sayer

[John Williamson]

dennis@home wrote:
> On 09/05/2013 19:15, Chris Hogg wrote:

>> The item came up on our local BBC TV this evening. Apparently it's
>> guidance issued by Devon&Somerset Fire and Rescue Authority, as
>> opposed to an on-the-spot decision by the fire officer in charge.
>> They're worried that the fire crew may be electrocuted when hoses are
>> sprayed onto the panels or exposed wiring. The makers of the solar
>> panels say it can't happen.
>>

They are, of course, willing to conduct the experiment by spraying the
water onto an overheated set of their solar panels while holding the
brass end? No? I didn't think so...

>
> So what's the big electrical different between the water from the hoses
> and rain?
> Solar panels sit in all sorts of weather and nobody gets electrocuted
> because they are wet.

One important difference is that rain isn't being delivered at high
pressure through a hose with a conductive end fitting being held by an
earthed fireman. It's also slightly less conductive than most tapwater.

--
Tciao for Now!

John.

[js...@ntlworld.com]

On Wednesday, May 8, 2013 4:21:13 PM UTC+1, Nightjar wrote:
> On 08/05/2013 14:22, Dave Liquorice wrote:
> > On Wed, 08 May 2013 12:11:19 +0100, newshound wrote:
> >> Normally, there is a readily accessible isolator for the incoming mains
> >> right by the front door.
>

> > Some commercial places have external "Firemans Switches" not sure what
> > they do ...
>
> They are usually there to disconnect neon signs.

and specifically HID lighting as I recall.

[js...@ntlworld.com]

On Thursday, May 9, 2013 9:10:56 PM UTC+1, John Williamson wrote:
> One important difference is that rain isn't being delivered at high
> pressure through a hose with a conductive end fitting being held

1m of water has quite a high resistance.

a) additional external thermal fuses on a per-panel, 85oC or even 63oC trigger would be sufficient to drop out panels.

b) N.O. relay on every panel which disconnects following loss of external 240V power (SELV relay feed supplied from a grid PSU).

Sounds like we might also need thermal fuses on the connection boxes using a system like "b)".

[Dave Liquorice]

On Thu, 09 May 2013 19:45:43 +0100, dennis@home wrote:

> So what's the big electrical different between the water from the hoses
> and rain?
> Solar panels sit in all sorts of weather and nobody gets electrocuted
> because they are wet.

How about a solar panel heated to a few hundred degrees from the fire
below and sprayed with loads of cold water? Will the glass take that sort
of thermal shock or just explode? Then of course is the insulation on the
wiring from the live panels, at over 500V DC, able to withstand a fire
where it can easily get to over 1000C inside the building?

--
Cheers
Dave.

[dennis@home]

Stunning lack from you.
You just haven't thought about what happens if the fire happens while
its raining, but you don't think at all AFAICS.

[harry]

Well if the fire had got that bad, not a lot to save.

[harry]

On May 9, 9:10 pm, John Williamson <johnwilliam...@btinternet.com>
wrote:

.

I think probably more danger from the wiring that the panels.

[harry]

There was a programme on the TV about "Is is possible to get
electrocuted by pissing on a live/third rail"?

They did a lot of tests and the answer was no, not really.

[dennis@home]

On 09/05/2013 21:10, John Williamson wrote:
> dennis@home wrote:
>> On 09/05/2013 19:15, Chris Hogg wrote:
>
>>> The item came up on our local BBC TV this evening. Apparently it's
>>> guidance issued by Devon&Somerset Fire and Rescue Authority, as
>>> opposed to an on-the-spot decision by the fire officer in charge.
>>> They're worried that the fire crew may be electrocuted when hoses are
>>> sprayed onto the panels or exposed wiring. The makers of the solar
>>> panels say it can't happen.
>>>
> They are, of course, willing to conduct the experiment by spraying the
> water onto an overheated set of their solar panels while holding the
> brass end? No? I didn't think so...

I can't see why they wouldn't be prepared to do that.

>>
>> So what's the big electrical different between the water from the
>> hoses and rain?
>> Solar panels sit in all sorts of weather and nobody gets electrocuted
>> because they are wet.
>
> One important difference is that rain isn't being delivered at high
> pressure through a hose with a conductive end fitting being held by an
> earthed fireman. It's also slightly less conductive than most tapwater.
>

Well that raises some interesting questions..

First the question about the solar panels...

what potential is going to be between an earthed fire man and a floating
DC source? AFAIK there is no low impedance path to earth via the inverter.

What is the resistance of a water jet several feet long compared to all
the other paths caused by the water spill also going to earth.


Then there is the design of fire engines...

Isn't it rather poor H&S to design a pump to put water over unknown
electrical stuff without making provision to keep the metal bits bonded
to a safe potential?

What about the insulation in the protective clothing?


There are lots more questions that can be raised if anyone really wants
to know the true hazards, however small.

[Andy Champ]

On 10/05/2013 07:56, dennis@home wrote:
> what potential is going to be between an earthed fire man and a floating
> DC source? AFAIK there is no low impedance path to earth via the inverter.

I think there's a high chance that it will cease to float in the
circumstances. Either through damage to something, or because another
fireman is playing another hose on another part of the system.

Andy

[polygonum]

For fully detached building with plenty of space around, maybe true.

For a semi, a terraced, one right by several other buildings (typical of
cities), then failure to fight that one might have very severe
consequences for neighbours. And if any of the neighbours also have
solar panels...

--
Rod

[tony sayer]

In article <518c1f99$0$40754$c3e8da3$3304...@news.astraweb.com>,

Yes the firemen will get wetter than what they otherwise might do;)..

>but you don't think at all AFAICS.

Still smarting from, the dual RCD issue I see;!..

Theres a lot more to this then what it seems you realise. For one during
the night or most of the day in this climate there won't be much power
they are producing, the real danger is if the mains gets accidentally
connected to them and a current might then be conducted through the
water thats being played on the fire.

Course unless thats being pumped from a pond or simpler then that won't
be that conductive, suggest you look that up on the IEE site theres a
very good article on how conductive clean water isn't.

So where does the rain --connect-- them to;?.

Also what happens in the inverter unit?, how is that or does that
actually "connect" the panels to the mains incomer?..

--
Tony Sayer

[tony sayer]

In article <av2e6g...@mid.individual.net>, John Williamson
<johnwil...@btinternet.com> scribeth thus

So where is the other end of the rain connected to;?..
--
Tony Sayer

[dennis@home]

I was waiting for someone to be that silly..
what if the TV melts and you get mains on the TV aerial/sat dish?
Do firemen refuse to enter a house with a TV aerial in case its been
made live from the mains and is wet?

>
> Course unless thats being pumped from a pond or simpler then that won't
> be that conductive, suggest you look that up on the IEE site theres a
> very good article on how conductive clean water isn't.

Rain is not clean once its landed on a roof, it is full of stuff that
was on the roof before it rained.

>
> So where does the rain --connect-- them to;?.

The same place as the supposed water from the hose.. nowhere.

>
> Also what happens in the inverter unit?, how is that or does that
> actually "connect" the panels to the mains incomer?..
>

They are built to better standards than TVs are so if a live TV aerial
isn't a significant problem, mains getting through an inverter isn't.

[Nightjar]

On 10/05/2013 09:17, polygonum wrote:
> On 10/05/2013 07:11, harry wrote:

...

>> Well if the fire had got that bad, not a lot to save.
>>
> For fully detached building with plenty of space around, maybe true.
>
> For a semi, a terraced, one right by several other buildings (typical of
> cities), then failure to fight that one might have very severe
> consequences for neighbours. And if any of the neighbours also have
> solar panels...

As I read the original article, they didn't fail to fight the fire. They
simply didn't do so from inside the building. The result of that seems
to have been that they had to content themselves with containing it,
rather than extinguishing it as quickly as they would have liked. So,
Harry's house will probably be destroyed if his roof catches fire, but
any neighbours might be OK.

Colin Bignell

[harry]

On May 10, 9:03 am, tony sayer <t...@bancom.co.uk> wrote:
> In article <518c1f99$0$40754$c3e8da3$3304c...@news.astraweb.com>,

> dennis@home <den...@killspam.kicks-ass.net> scribeth thus
>
>
>
>
>
>
>
>
>
> >On 09/05/2013 20:07, tony sayer wrote:

> >> In article <518beede$0$15365$c3e8da3$9f400...@news.astraweb.com>,

There is electrical continuity through the latest inverters; they have
no transformer. But there is an isolator on both AC and DC sides.

[newshound]

On 10/05/2013 07:15, harry wrote:

> There was a programme on the TV about "Is is possible to get
> electrocuted by pissing on a live/third rail"?
>
> They did a lot of tests and the answer was no, not really.
>

I've never quite understood why they were not more dangerous.

Although there was a break in the third rail for foot crossings on the
South East Region suburban lines when I was a schoolkid, they were not
very far from the crossing point and some people (not me) would go up to
the third rail and kick it. Presumably, when you are standing on well
drained ballast with rubber shoes there is more than enough resistance
to earth to keep you safe.

People don't seem to get electrocuted when they fall on tube/underground
tracks either.

I don't recall hearing of anyone trying to lob a piece of metal to
bridge from the third rail to the adjacent rail. On wet winter evenings,
the arcing when a train passed would light up the low cloud and be
clearly visible from at least half a mile away, so I guess we treated
them with some respect.

We would regularly place pennies on the main rails to get them
flattened. The crossing was several hundred yards from the nearest
station, so there was no effective surveillance and maybe 100 junior and
secondary school kids used my local crossing every day.

[The Natural Philosopher]

On 10/05/13 17:18, newshound wrote:
> On 10/05/2013 07:15, harry wrote:
>
>> There was a programme on the TV about "Is is possible to get
>> electrocuted by pissing on a live/third rail"?
>>
>> They did a lot of tests and the answer was no, not really.
>>
>
> I've never quite understood why they were not more dangerous.
>
> Although there was a break in the third rail for foot crossings on the
> South East Region suburban lines when I was a schoolkid, they were not
> very far from the crossing point and some people (not me) would go up
> to the third rail and kick it. Presumably, when you are standing on
> well drained ballast with rubber shoes there is more than enough
> resistance to earth to keep you safe.
>
> People don't seem to get electrocuted when they fall on
> tube/underground tracks either.
>

The dcan and sio, but te thing is desingned to maoke it likely for
people to fall into a trebnch built for the purpose. I recall one or toe
poeple every yeasr got electrocuted on Southern Region when I was a kid.

> I don't recall hearing of anyone trying to lob a piece of metal to
> bridge from the third rail to the adjacent rail. On wet winter
> evenings, the arcing when a train passed would light up the low cloud
> and be clearly visible from at least half a mile away, so I guess we
> treated them with some respect.
>

NO, I heard one kid did it..but it was maybe apocryphal.

> We would regularly place pennies on the main rails to get them
> flattened. The crossing was several hundred yards from the nearest
> station, so there was no effective surveillance and maybe 100 junior
> and secondary school kids used my local crossing every day.

yes. I had too much respect to do that, but other kids did.

Also nicked detonators from railway huts and stuck them on the rails.
God that boy was a dick. I beleive he became a british rail porter. Too
thick to even pull a signal up and down.



--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

[PeterC]

Nowadays, it's in the cloud of course.
--
Peter.
The gods will stay away
whilst religions hold sway

[tony sayer]

>>>>>
>>>>> So what's the big electrical different between the water from the hoses
>>>>> and rain?
>>>>> Solar panels sit in all sorts of weather and nobody gets electrocuted
>>>>> because they are wet.
>>>>
>>>> Stunning knowledge of the leccy den;!...
>>>>
>>>
>>> Stunning lack from you.
>>> You just haven't thought about what happens if the fire happens while
>>> its raining,
>>
>> Yes the firemen will get wetter than what they otherwise might do;)..
>>
>>> but you don't think at all AFAICS.
>>
>> Still smarting from, the dual RCD issue I see;!..
>>
>> Theres a lot more to this then what it seems you realise. For one during
>> the night or most of the day in this climate there won't be much power
>> they are producing, the real danger is if the mains gets accidentally
>> connected to them and a current might then be conducted through the
>> water thats being played on the fire.
>
>I was waiting for someone to be that silly..
>what if the TV melts and you get mains on the TV aerial/sat dish?
>Do firemen refuse to enter a house with a TV aerial in case its been
>made live from the mains and is wet?

>>>> So what's the big electrical different between the water from the hoses
>>>> and rain?

Yes what is it?..

>
>
>>
>> Course unless thats being pumped from a pond or simpler then that won't
>> be that conductive, suggest you look that up on the IEE site theres a
>> very good article on how conductive clean water isn't.
>
>Rain is not clean once its landed on a roof, it is full of stuff that
>was on the roof before it rained.

Yes but what is it "connected" to?..

>
>>
>> So where does the rain --connect-- them to;?.
>
>The same place as the supposed water from the hose.. nowhere.

So where is the rain thats landing on the roof connected to, to conduct
a flow of leccy to the firemen?..

>
>>
>> Also what happens in the inverter unit?, how is that or does that
>> actually "connect" the panels to the mains incomer?..
>>
>
>They are built to better standards than TVs are so if a live TV aerial
>isn't a significant problem, mains getting through an inverter isn't.
>

Well lets look at the relative sizes of Solar panels and their locations
and a TV aerial, one covers a very large area the other doesn't..
--
Tony Sayer

[tony sayer]

In article <57fb3103-8819-46bd...@w15g2000vbn.googlegroup
s.com>, harry <harry...@btinternet.com> scribeth thus

No transformers?, so how is the isolation achieved then Harry?..
--
Tony Sayer

[tony sayer]

In article <518d1dad$0$26051$c3e8da3$1f4c...@news.astraweb.com>,
newshound <news...@stevejqr.plus.net> scribeth thus

>On 10/05/2013 07:15, harry wrote:
>
>> There was a programme on the TV about "Is is possible to get
>> electrocuted by pissing on a live/third rail"?
>>
>> They did a lot of tests and the answer was no, not really.
>>
>
>I've never quite understood why they were not more dangerous.
>
>Although there was a break in the third rail for foot crossings on the
>South East Region suburban lines when I was a schoolkid, they were not
>very far from the crossing point and some people (not me) would go up to
>the third rail and kick it. Presumably, when you are standing on well
>drained ballast with rubber shoes there is more than enough resistance
>to earth to keep you safe.

You could get away with that, there're normally at 750 volts DC relative
to the other running rails so yep, could be done seeing that most shoes
these days are plastic composition as long as there're not that wet or
contaminated..

>
>People don't seem to get electrocuted when they fall on tube/underground
>tracks either.

They do but not AFAIR that often. IIRC its -210 volts and appx 420 V on
the outer rail with the running rails being "tied" by resistors so you'd
have to have a decent grip or connection with a 400 rail and a running
rail.

>
>I don't recall hearing of anyone trying to lob a piece of metal to
>bridge from the third rail to the adjacent rail. On wet winter evenings,
>the arcing when a train passed would light up the low cloud and be
>clearly visible from at least half a mile away, so I guess we treated
>them with some respect.

Yes impressive that, good ole Arc. Overhead lines are quite impressive
especially Ice coated ones;)..

>
>We would regularly place pennies on the main rails to get them
>flattened. The crossing was several hundred yards from the nearest
>station, so there was no effective surveillance and maybe 100 junior and
>secondary school kids used my local crossing every day.

Yep best done with Steam Loco's and that did teach us not to get
anywhere near them when they were running;!!>..
--
Tony Sayer

[tony sayer]

In article <518c9a20$0$7719$c3e8da3$12bc...@news.astraweb.com>,
dennis@home <den...@killspam.kicks-ass.net> scribeth thus

>On 09/05/2013 21:10, John Williamson wrote:
>> dennis@home wrote:
>>> On 09/05/2013 19:15, Chris Hogg wrote:
>>
>>>> The item came up on our local BBC TV this evening. Apparently it's
>>>> guidance issued by Devon&Somerset Fire and Rescue Authority, as
>>>> opposed to an on-the-spot decision by the fire officer in charge.
>>>> They're worried that the fire crew may be electrocuted when hoses are
>>>> sprayed onto the panels or exposed wiring. The makers of the solar
>>>> panels say it can't happen.
>>>>
>> They are, of course, willing to conduct the experiment by spraying the
>> water onto an overheated set of their solar panels while holding the
>> brass end? No? I didn't think so...
>
>I can't see why they wouldn't be prepared to do that.
>
>>>
>>> So what's the big electrical different between the water from the
>>> hoses and rain?
>>> Solar panels sit in all sorts of weather and nobody gets electrocuted
>>> because they are wet.
>>
>> One important difference is that rain isn't being delivered at high
>> pressure through a hose with a conductive end fitting being held by an
>> earthed fireman. It's also slightly less conductive than most tapwater.
>>
>
>Well that raises some interesting questions..
>
>First the question about the solar panels...
>
>what potential is going to be between an earthed fire man and a floating
>DC source? AFAIK there is no low impedance path to earth via the inverter.
>

Which normally there might well not be but under fault conditions?..

>What is the resistance of a water jet several feet long compared to all
>the other paths caused by the water spill also going to earth.
>

Doesn't really matter if the panels are live then their live and a few
leakage paths aren't going to make that much difference..

>
>Then there is the design of fire engines...
>
>Isn't it rather poor H&S to design a pump to put water over unknown
>electrical stuff without making provision to keep the metal bits bonded
>to a safe potential?

Yes they really ought to thump an earthing rod into the ground before
deploying them and perhaps an earthed braid in the hose like they do
with high voltage supply lies in TV transmitters where they used to use
a co-ax cable:)..

>
>What about the insulation in the protective clothing?

What about it when all is wet and damp?.

>
>
>There are lots more questions that can be raised if anyone really wants
>to know the true hazards, however small.

Yes what current needs to flow thru the human fame before serious damage
arises?, its not that much, its in the low milliamp region..
--
Tony Sayer

[John Williamson]

<Chuckle> By Super Capacitors (tm), of course.

[John Williamson]

dennis@home wrote:
> On 09/05/2013 21:10, John Williamson wrote:
>> dennis@home wrote:
>>> On 09/05/2013 19:15, Chris Hogg wrote:
>>
>>>> The item came up on our local BBC TV this evening. Apparently it's
>>>> guidance issued by Devon&Somerset Fire and Rescue Authority, as
>>>> opposed to an on-the-spot decision by the fire officer in charge.
>>>> They're worried that the fire crew may be electrocuted when hoses are
>>>> sprayed onto the panels or exposed wiring. The makers of the solar
>>>> panels say it can't happen.
>>>>
>> They are, of course, willing to conduct the experiment by spraying the
>> water onto an overheated set of their solar panels while holding the
>> brass end? No? I didn't think so...
>
> I can't see why they wouldn't be prepared to do that.
>

I can. If they had done it, there woud be a video of it happening somewhere.

>>>
>>> So what's the big electrical different between the water from the
>>> hoses and rain?
>>> Solar panels sit in all sorts of weather and nobody gets electrocuted
>>> because they are wet.
>>
>> One important difference is that rain isn't being delivered at high
>> pressure through a hose with a conductive end fitting being held by an
>> earthed fireman. It's also slightly less conductive than most tapwater.
>>
>
> Well that raises some interesting questions..
>
> First the question about the solar panels...
>
> what potential is going to be between an earthed fire man and a floating
> DC source? AFAIK there is no low impedance path to earth via the inverter.
>

There's no guarantee that the DC source will remain floating in a fire
situation. If, say, the fire burns through the insulation on a couple of
cables in the installation, there will be anything up to 700 volts
relative to earth on the loose, according to your figures.

> What is the resistance of a water jet several feet long compared to all
> the other paths caused by the water spill also going to earth.
>

Low enough to give enough voltage at the hose end for a lethal, or at
least disabling, current to flow. I urge you to try the experiment. If
you haven't yet bred, there would probbaly be a Darwin Award in it for you.

>
> Then there is the design of fire engines...
>
> Isn't it rather poor H&S to design a pump to put water over unknown
> electrical stuff without making provision to keep the metal bits bonded
> to a safe potential?
>

Instructions are given, and reinforced by training to never knowingly
use water on any fire where electicity may be flowing.

> What about the insulation in the protective clothing?
>

It works fine if it's perfectly dry. Unfortunately, when you're holding
the business end of a fire hose you *do* get wet. And if you're not wet
from the water being sprayed around in great quantities, you're probably
sweating copiously inside the clothing, too, although with sweat being a
good conductor, that may channel some of the current away from the core
of your body and along your skin.

>
> There are lots more questions that can be raised if anyone really wants
> to know the true hazards, however small.

The going rate is one life lost to ten houses saved without any damage
at all, roughly, if all you're counting is the money.... If you're not
totally mercenary, any life lost in attempting to fight a fire only
involving property is one too many, as buildings can be replaced, but a
life lost affects many others, with no possibility of replacement ot
*that* person.

[Dave Liquorice]

On Fri, 10 May 2013 18:47:15 +0100, tony sayer wrote:

>> There is electrical continuity through the latest inverters; they have
>> no transformer. But there is an isolator on both AC and DC sides.
>
> No transformers?, so how is the isolation achieved then Harry?..

Er, a switch as in relay?

--
Cheers
Dave.

[harry]

On May 10, 6:47 pm, tony sayer <t...@bancom.co.uk> wrote:
> In article <57fb3103-8819-46bd-89c4-87b138327...@w15g2000vbn.googlegroup
> s.com>, harry <harry130...@btinternet.com> scribeth thus

It isn't. So that is where the danger lies. One end of the solar panel
string is connected to the line/phase conductor. (via electronic
components)
The older systems ran at very low voltages and had a transformer. One
side of the panels was earthed back then.

The newer ones have no transformer and are much more efficient.
(Around 95%)
However when the output from the panel falls below the peak voltage of
the mains (around 340 volts) they shut down.
There is a bank of capacitors in the inverter too, that just makes
them more dangerous again.

[harry]

On May 10, 11:02 pm, "Dave Liquorice" <allsortsnotthis...@howhill.com>
wrote:

You got the wrong end of the stick.
In the old systems there was a transformer which meant the systems on
the primary and secondary sides were not electrically connected. They
were "isolated" from each other by the insulation on the transformer
windings.

Like your electric train set was not connected to the mains.

There's a bit here on the technology.
There's a few people here need to read up before shooting their mouth
s off.
http://en.wikipedia.org/wiki/Grid_tie_inverter#Technology

[Nightjar]

On 10/05/2013 16:29, Huge wrote:

> On 2013-05-10, Nightjar <c...@insert.my.surname.here.me.uk> wrote:
>
>> As I read the original article, they didn't fail to fight the fire. They
>> simply didn't do so from inside the building. The result of that seems
>> to have been that they had to content themselves with containing it,
>> rather than extinguishing it as quickly as they would have liked. So,
>> Harry's house will probably be destroyed if his roof catches fire, but
>> any neighbours might be OK.
>

> So, a win-win, then.

Make sure your alibi is sound.

Colin Bignell

[tony sayer]

>>
>> >There is electrical continuity through the latest inverters; they have
>> >no transformer. �But there is an isolator on both AC and DC sides.
>>
>> No transformers?, so how is the isolation achieved then Harry?..
>> --
>> Tony Sayer
>
>It isn't. So that is where the danger lies. One end of the solar panel
>string is connected to the line/phase conductor. (via electronic
>components)

What components would they be then?..

>The older systems ran at very low voltages and had a transformer. One
>side of the panels was earthed back then.
>
>The newer ones have no transformer and are much more efficient.
>(Around 95%)

Sure theres not a transformer, very much like a switch mode power supply
but in reverse?..

>However when the output from the panel falls below the peak voltage of
>the mains (around 340 volts) they shut down.
>There is a bank of capacitors in the inverter too, that just makes
>them more dangerous again.

--
Tony Sayer

[Grimly Curmudgeon]

On Wed, 08 May 2013 15:34:02 +0100, newshound
<news...@fairadsl.co.uk> wrote:

>Use high pressure hoses to disrupt the panels first?

Ballista? A fire tender with a large rock throwing device and trailer
full of boulders would disrupt them quite well, iwt.

[harry]

To be isolated, it is deemed there has to be physical separation/
break in the (all) conductors. Electronic switching devices don't do
this.

[dennis@home]

On 12/05/2013 07:44, harry wrote:

> To be isolated, it is deemed there has to be physical separation/
> break in the (all) conductors. Electronic switching devices don't do
> this.
>

No fault isolation relay fitted?

[tony sayer]

In article <mknto8tn93qjlsq13...@4ax.com>, Grimly
Curmudgeon <gri...@gmail.com> scribeth thus

Eee!, bet them Romans 'ud be mighty proud that their inventions lasted
so long;)...

--
Tony Sayer

[tony sayer]

In article <07a88824-15ac-4a96...@y5g2000vbg.googlegroups

.com>, harry <harry...@btinternet.com> scribeth thus

Transformers do provide galvanic isolation. This is like in a switch
mode power supply so when its going neither sides of the incoming mains
have a direct path to the output...

--
Tony Sayer

[harry]

On May 12, 11:34 am, tony sayer <t...@bancom.co.uk> wrote:
> In article <07a88824-15ac-4a96-bd57-cc73e3cf7...@y5g2000vbg.googlegroups
> .com>, harry <harry130...@btinternet.com> scribeth thus

The point was there are no transformers in the latest grid tie
inverters.

[tony sayer]

In article <c4041076-5bb9-4382...@s8g2000vbw.googlegroups

.com>, harry <harry...@btinternet.com> scribeth thus

So are the panels then directly connected to either side of the mains
supply?..

--
Tony Sayer

[Windmill]

An excellent example of creative lateral thinking !

--
Windmill, Til...@Nonetel.com Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost

[Windmill]

John Williamson <johnwil...@btinternet.com> writes:

[.................]

>The going rate is one life lost to ten houses saved without any damage
>at all, roughly, if all you're counting is the money.... If you're not
>totally mercenary, any life lost in attempting to fight a fire only
>involving property is one too many, as buildings can be replaced, but a
>life lost affects many others, with no possibility of replacement ot
>*that* person.

Amen to that. (Even the religious seem less than keen to hasten off to
their hereafter.)

[harry]

On May 12, 9:48 pm, tony sayer <t...@bancom.co.uk> wrote:
> In article <c4041076-5bb9-4382-83b4-9d343a097...@s8g2000vbw.googlegroups

Yes. Via electronic components.
Why don't you read the link I posted if the topic is so interesting to
you?

[dennis@home]

On 13/05/2013 08:24, harry wrote:
> On May 12, 9:48 pm, tony sayer <t...@bancom.co.uk> wrote:

8<

>>>> --
>>>> Tony Sayer
>>
>>> The point was there are no transformers in the latest grid tie
>>> inverters.
>>
>> So are the panels then directly connected to either side of the mains
>> supply?..
>>
>> --
>> Tony Sayer
>
> Yes. Via electronic components.
> Why don't you read the link I posted if the topic is so interesting to
> you?
>

You are wasting your time.
No matter how simply you explain anything to him he will ask the same
sort of stupid question.
He is like a four year old that keeps saying Why?

[tony sayer]

>> >> >> >However when the output from the panel falls below the peak voltage of
>> >> >> >the mains (around 340 volts) they shut down.
>> >> >> >There is a bank of capacitors in the inverter too, that just makes
>> >> >> >them more dangerous again.
>>
>> >> >> --
>> >> >> Tony Sayer
>>
>> >> >To be isolated, it is deemed there has to be physical separation/
>> >> >break in the (all) conductors. Electronic switching devices don't do
>> >> >this.
>>
>> >> Transformers do provide galvanic isolation. This is like in a switch
>> >> mode power supply so when its going neither sides of the incoming mains
>> >> have a direct path to the output...
>>
>> >> --
>> >> Tony Sayer
>>
>> >The point was there are no transformers in the latest grid tie
>> >inverters.
>>
>> So are the panels then directly connected to either side of the mains
>> supply?..
>>
>> --
>> Tony Sayer
>
>Yes. Via electronic components.
>Why don't you read the link I posted if the topic is so interesting to
>you?

It doesn't actually say I thought that you'd know Harry?...

--
Tony Sayer

[tony sayer]

In article <5190bff5$0$1184$c3e8da3$fdf4...@news.astraweb.com>,
dennis@home <den...@killspam.kicks-ass.net> scribeth thus

Yes Den, if you don't ask you don't get answers...

Quite simple really when you think about it....

--
Tony Sayer

[mcp]

On Mon, 13 May 2013 02:42:58 GMT, spam-n...@Onetel.net.uk.invalid
(Windmill) wrote:

>Grimly Curmudgeon <gri...@gmail.com> writes:
>
>>On Wed, 08 May 2013 15:34:02 +0100, newshound
>><news...@fairadsl.co.uk> wrote:
>
>>>Use high pressure hoses to disrupt the panels first?
>
>>Ballista? A fire tender with a large rock throwing device and trailer
>>full of boulders would disrupt them quite well, iwt.
>
>An excellent example of creative lateral thinking !

Just put a couple of snooker balls in the hose before turning the
water on.