Double fused spur
Mark Trueman
I have been told that i need to convert a double plug socket to a
fused spur. The double plug currently supplies power to the ch/hw
timer and the ignition for the gas fire on my baxi boiler (which are
just plugged in using 3 amp fused 3 pin plugs at the moment). Assuming
that it is the case that i need to change this double plug to fused
spur, how do i go about it considering that the double socket is a
spur off the ring main. Can you get a "double fused spur" so that a
fused spur off the ring main can service 2 appliances or is there a
different way to go about it. Laminate flooring prevents me from
creating another spur so the easiest option is out of the question.
Thanks
Mark
Andrew Gabriel
mark.tr...@agfa.co.uk (Mark Trueman) writes:
> Hi group
>
> I have been told that i need to convert a double plug socket to a
> fused spur.
Sounds somewhat bogus.
I would have installed a fused spur in the first place, but I
wouldn't bother changing what you have just for the sake of it.
The only issue I can think of is that switching off the CH from
the mains power might screw up the clock, and would defeat any
pump overrun, so you shouldn't do it as a matter of course.
--
Andrew Gabriel
Consultant Software Engineer
Dave Plowman
I can't see how a plug and socket arrangement isn't satisfactory, as the
prime requirement is isolation of the boiler for servicing etc. And
removing a plug is infinite isolation....
You can, however, fit two spurs side by side. The bad news is that the
backing box (assuming they're flush) has to be changed to a dual type as
two singles are wider than one double. You might not find these in the
sheds - but a wholesaler will stock them.
--
*We are born naked, wet, and hungry. Then things get worse.
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
ARWadsworth
> prime requirement is isolation of the boiler for servicing etc. And
> removing a plug is infinite isolation....
>
Fixed appliances need fused spurs not plugs. Especially gas appliances, as
CORGI fitters just love to point out to us electricians.
Adam
Ed Sirett
Dave Plowman <dave....@argonet.co.uk> wrote in message
news:4b68e6a6c7...@argonet.co.uk...
> In article <efbd4d01.02082...@posting.google.com>,
> Mark Trueman <mark.tr...@agfa.co.uk> wrote:
> > I have been told that i need to convert a double plug socket to a
> > fused spur. The double plug currently supplies power to the ch/hw
> > timer and the ignition for the gas fire on my baxi boiler (which are
> > just plugged in using 3 amp fused 3 pin plugs at the moment). Assuming
> > that it is the case that i need to change this double plug to fused
> > spur, how do i go about it considering that the double socket is a
> > spur off the ring main. Can you get a "double fused spur" so that a
> > fused spur off the ring main can service 2 appliances or is there a
> > different way to go about it. Laminate flooring prevents me from
> > creating another spur so the easiest option is out of the question.
>
> I can't see how a plug and socket arrangement isn't satisfactory, as the
> prime requirement is isolation of the boiler for servicing etc. And
> removing a plug is infinite isolation....
>
connection unit or by an _unswitched_ socket (forcng removal to switch the
power off). The thinking is that if there were a polarity reversal simply
switching off at the socket would not be safe.
However I think this is a load of bollocks since I don't think that opening
up a live (non-leaking) boiler presents any electrical hazard to someone
who knows what they are doing unless they go out of their way to touch the
230V supply.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Mark Trueman
put fused spurs in or can i leave it as it is. I think the guy who serviced
my boiler was just after as much work as he could get. He wanted to wire in
my cooker and hood after i asked him to fit the hob and oven. I told him i
could do electrics but he still insisted. Eventually he gave in.
Anyway, if i DO have to do this fused spur thingy, how do i get 2 fused
spurs wired up off one spur. Can i just split the ring main spur cable into
both the fused spurs or do i have to do something else.
Also, does a back boiler have to be completely blocked in. What i mean by
this is that one side of the chimney breast that holds the boiler has a 1ft
"access point" in it (left by the previous owners). You can get to the
boiler through this access point. I was told by my friendly corgi fitter
that i HAD to block this up with "fireproof plasterboard" or bricks. Is this
correct. He also said i had to put mastik around the fire surround as he
could "see light" between the surround and the wall. Is this bolx or not??
Thanks
Mark
"Ed Sirett" <e...@makewrite.demon.co.uk> wrote in message
news:1029871299.7620.2...@news.demon.co.uk...
Dave Plowman
Ed Sirett <e...@makewrite.demon.co.uk> wrote:
> It is recommended that CH systems are powered either from a fused,
> switched connection unit or by an _unswitched_ socket (forcng removal to
> switch the power off). The thinking is that if there were a polarity
> reversal simply switching off at the socket would not be safe.
Suppose so. But it would take a plumber with the intelligence of Adam not
to pull the plug out before servicing rather than relying on the switch.
> However I think this is a load of bollocks since I don't think that
> opening up a live (non-leaking) boiler presents any electrical hazard to
> someone who knows what they are doing unless they go out of their way
> to touch the 230V supply.
Don't know that much about modern boilers, but all domestic electronics
should have the mains side shrouded against accidental touching even when
uncased.
--
*One nice thing about egotists: they don't talk about other people.
Ian Clowes
> Anyway, if i DO have to do this fused spur thingy, how do i get 2 fused
> spurs wired up off one spur. Can i just split the ring main spur cable into
> both the fused spurs or do i have to do something else.
I don't believe regs allow you to replace the double socket with two
spurs, even if you put a 3A fuse in each spur.
It does depend on your setup a bit, but assuming you have a
standard-ish dw/ch clock and boiler arrangement then they'd typically
be powered from a single spur anyway. It sounds like they've been
installed in a slightly odd manner if they are standard units.
The normal thing to do would be to run 2+E to a 10-way CH connector
block, and run out to the boiler, timeclock, valves, etc from there.
Honeywell and others do these along with standard wiring diagrams for
C-plan, etc. You sometimes find enough connector block within the
boiler casing to achieve what you need. Or if you don't mind wasting a
bit of wall space you can buy one of these blocks for a few pounds
from and plumbers merchant or Screwfix. They consist of connector
strip plus white plastic housing for surface mounting.
If not you may find a 'dual' electrical mounting box (ie one that will
accept two single sockets or equivalent) can replace the current twin
one. This would allow you to put the fused spur one one half of it,
and provide space in the other half for the connector block with a
blanking plate over the top. A divider in the middle might be useful
for this.
This is electrically equivalent to just putting both sets of wires
that are currently in the plugs directly into the new FU's out
terminals, but that probably isn't allowed for some reason...
In short, you shouldn't have to mess around too much with decor
damaging electrical work, but may end up getting a few new wiring bits
to make the job up to spec.
HTH
IanC
Stefek Zaba
> "Mark Trueman" <markt...@NOSPAMdsl.pipex.com> wrote in message news:<3d629a9b$0$8514$cc9e...@news.dial.pipex.com>...
> > Anyway, if i DO have to do this fused spur thingy, how do i get 2 fused
> > spurs wired up off one spur. Can i just split the ring main spur cable into
> > both the fused spurs or do i have to do something else.
> I don't believe regs allow you to replace the double socket with two
> spurs, even if you put a 3A fuse in each spur.
In fact they do: there's no problem putting two fused connection units
onto s single spur cable (i.e. "daisy-chaining" the 2.5mmsq cable into
the first FCU, and out from there into the second one). Indeed the
letter of the Regs would allow you to wire that spur in thinner-than-2.5mmsq
on the grounds that it was feeding two fixed loads not capable of causing
an overload: but that would be a Bad Idea for future extensibility, and
there's no need since you presumably have the 2.5mmsq coming in to the
existing socket.
As others have said, Mark's current arrangement is "nearly OK". The simplest
way of getting it to conform to best practice is to replace the current
double switched socket with an *unswitched* double - this forces anyone
isolating the appliance to "really" isolate it, rather than switching only
the live pole. This has the great merit of not requiring any change to the
back box.
If you want to use fused connection units to keep your CORGI happy, there's
a lower-cost more-work way and a higher-cost less-work one, both of which
give you two FCU's side by side. The lower-cost one, as the estimable Mr
Plowman mentions, is to change the current double backbox for a "dual" one,
as a "double" is narrower than two singles. Any electrical distributor will
have these in stock, and the larger sheds usually carry them too; you'll
know whether you need surface-mount, "normal" galvanised, or hollow-wall
wing-grip, according to the type of wall you have. The "same size hole,
costs more" alternative is to use gridswitch components: MEM make fused
connection units as part of their "Supergrid" range, and you could fit two
of these and the flex-outlet module in a 4-way grid module which fits a
(deep enough!) standard double wall box. But it's pricey (around 30 squid
for all the bits), and you might have to dig out brick to increase the
depth for the back box...
HTH, Stefek
chris French
<dave....@argonet.co.uk> writes
>In article <1029871299.7620.2...@news.demon.co.uk>,
> Ed Sirett <e...@makewrite.demon.co.uk> wrote:
>> However I think this is a load of bollocks since I don't think that
>> opening up a live (non-leaking) boiler presents any electrical hazard to
>> someone who knows what they are doing unless they go out of their way
>> to touch the 230V supply.
>
>Don't know that much about modern boilers, but all domestic electronics
>should have the mains side shrouded against accidental touching even when
>uncased.
>
metal box inside the main casing.
--
Chris French, Leeds
Mark Trueman
i will just get 2 fused units and daisy chain them together with 2.5te.
Should be an easy replacement
Thanks
Mark
"Stefek Zaba" <sj...@hplb.hpl.hp.com> wrote in message
news:ak0i64$b1g$1...@murdoch.hpl.hp.com...
Ed Sirett
>
> Don't know that much about modern boilers, but all domestic electronics
> should have the mains side shrouded against accidental touching even when
> uncased.
>
Not withstanding that most boiler diagnosis has to take place with the power
on.
Ed Sirett
Mark Trueman <markt...@NOSPAMdsl.pipex.com> wrote in message
news:3d629a9b$0$8514$cc9e...@news.dial.pipex.com...
>
> this is that one side of the chimney breast that holds the boiler has a
1ft
> "access point" in it (left by the previous owners). You can get to the
> boiler through this access point. I was told by my friendly corgi fitter
> that i HAD to block this up with "fireproof plasterboard" or bricks. Is
this
> correct. He also said i had to put mastik around the fire surround as he
> could "see light" between the surround and the wall. Is this bolx or not??
>
> Thanks
>
The difinitive answers are in the installation and servicing manual.
In general BBUs have to have all the pipe work covered to prevent corrosion
and all the extra* openings into the chimney blocked (say by well stuffed
rock wool).
* = Obviously there has to be a supply of combustion and cooling air but
this should arranged in the manner intended by the manufacturers.
Get the manual and find out what really needs doing.
Ade
Mark Trueman wrote:
>
> Thanks for your help. The current double socket is a surface mounted box so
> i will just get 2 fused units and daisy chain them together with 2.5te.
> Should be an easy replacement
As Stefek stated, this is fine, but I would really question the need to
do it in the first place. The installation manual for my boiler
[Chaffoteaux Celtic - I know, I know, but I was young & naive and
thought that BG represented the pinnacle of CH installation.....! How
quickly one learns :-) ] specifically states the preferred method of
mains connection to be a plug & unswitched socket, with a fused spur
mentioned as a sort of "well, if you really must" sort of second best
(not that that stopped me from ripping out BG's tangle of
draped-everywhere flex for a much neater install fed from a fused spur,
but I was rewiring at the time anyway so it made sense). Unless *you*
desperately want to replace your current set-up for reasons of neatness
or whatever, I'd just leave as-is. If your CORGI whines, ask him to
state which chapter/paragraph of BS7671 specifically forbids it, or
where in the boiler's installation manual it states that a plug & socket
must not be used. Even better, find yourself a new CORGI, especially
since you suspect that this one is just after as much work as he can
get. IME, and seemingly that of others, *good* tradesmen don't have to
invent unnecessary work 'cos they're usually booked solid with 'real'
jobs! Just my £0.02.
Ian Clowes
> In uk.d-i-y, Ian Clowes (clowe...@hotmail.com) wrote:
> > I don't believe regs allow you to replace the double socket with two
> > spurs, even if you put a 3A fuse in each spur.
>
> In fact they do: there's no problem putting two fused connection units
> onto s single spur cable (i.e. "daisy-chaining" the 2.5mmsq cable into
> the first FCU, and out from there into the second one).
Hi
Just to clarify this...
I meant that you wouldn't be permitted to bring feed into inputs of
FCU1 and then take another short length of 2.5mmsq from thiose inputs
to the inputs of FCU2.
I can see that running FCU2 from the _outputs_ of FCU1 would be OK,
since the fuse in FCU1 would be protecting the original supply cable.
So, you can't get to the position of having two independently
switchable FCUs. In particular you can't achieve FCU1 oiff but FCU2
on, but you can get an arrangement where FCU2 is off or both FCU1 and
FCU2 are off.
Is that what you meant as well, or have I got this wrong?
IanC
Christopher Bonet
: Just to clarify this...
: I meant that you wouldn't be permitted to bring feed into inputs of
: FCU1 and then take another short length of 2.5mmsq from thiose inputs
: to the inputs of FCU2.
: I can see that running FCU2 from the _outputs_ of FCU1 would be OK,
: since the fuse in FCU1 would be protecting the original supply cable.
: So, you can't get to the position of having two independently
: switchable FCUs. In particular you can't achieve FCU1 oiff but FCU2
: on, but you can get an arrangement where FCU2 is off or both FCU1 and
: FCU2 are off.
One thing that could be done would be to have an additional *unswitched*
FCU (fitted with a 13A fuse) that protects the supply cable, the output of
which feeds (in parallel) two individual switched FCU's each fitted with a
3A fuse to protect the flex to the boiler, etc. that they feed.
The unswitched FCU could be located with the other two or, if it is more
convenient in terms of decoration, on the ring at the origin of the spur
cable (in which case appropriate labelling would seem called for).
Chris.
--
Christopher Bonet c.b...@physics.org
(Please note that the address cb...@york.ac.uk is no longer in use)
Stefek Zaba
> I meant that you wouldn't be permitted to bring feed into inputs of
> FCU1 and then take another short length of 2.5mmsq from thiose inputs
> to the inputs of FCU2.
And I meant that you *are* so permitted. The restriction on unfused spurs
is for *sockets*, since you don't know what will be plugged into sockets
and it's conceivable that they'd be high-current loads, overloading the
shared section of 2.5mmsq cable. In this case, though, we're talking two
(small) *fixed* loads, supplied through FCUs, neither of which (if I
remember aright, a gas fire fan motor and a CH boiler) are the type of
load which can cause an overload. I don't have my copy of the On-Site Guide
to hand, nor the text of the Regs themselves, but I'm confident of this.
(Still doesn't mean I'm right, mind ;-) The relevant Regs from which this
derives are the ones concerned with overcurrent and fault current protection:
here, both the nature of the loads and the fuses in the FCU (both 3A) prevent
an *overcurrent*, while the fusing for the ring off which the spur comes
takes care of the fault current.
Cheers, Stefek
Mark Trueman
FYI, all it will be running is the ch timer and therefore the ch pump (which
i believe runs off the power supplied to the timer) and the ignition for the
crappy gas fire. The gas fire is never used so it needn't be taken into
account really.
Anyway, all seems fine. Now im tiling the darned bathroom. SWMBO has been
obeyed
Thanks
Mark
"Stefek Zaba" <sj...@hplb.hpl.hp.com> wrote in message
news:ak812v$eat$1...@murdoch.hpl.hp.com...
Andy Wade
<ak812v$eat$1...@murdoch.hpl.hp.com>...
> And I meant that you *are* so permitted. The restriction on unfused
> spurs is for *sockets*, since you don't know what will be plugged into
> sockets and it's conceivable that they'd be high-current loads,
> overloading the shared section of 2.5mmsq cable. In this case, though,
> we're talking two (small) *fixed* loads, supplied through FCUs, neither
> of which (if I remember aright, a gas fire fan motor and a CH boiler)
> are the type of load which can cause an overload. I don't have my copy
> of the On-Site Guide to hand, nor the text of the Regs themselves, but
> I'm confident of this. (Still doesn't mean I'm right, mind ;-)
Well, what the latest version of the On-Site Guide (Appendix 8) says is
this:
"A non-fused spur feeds only one single or one twin or multiple
socket-outlet or one permanently connected equipment."
So, strictly speaking, if you do what is being proposed here you will be
deviating from the 'standard circuit arrangement' of the OSG. That
doesn't mean that you'll fail to comply with BS 7671 - indeed the
introduction to Appendix 8 includes the words "circuit arrangements other
than those detailed in this appendix are not precluded when specified by
a suitably qualified electrical engineer, in accordance with the general
requirements of Regulation 314-01-03." So, Mr. Zaba, I declare you to be
simultaneously both right and wrong. Clearly you _are_ Schroedinger's
cat, AICMFP.
Interestingly, there are two relaxations in regard to unfused spurs in
the new (blue) OSG. The first is the reference to multiple
socket-outlets, quoted above. The assumption here is presumably that all
multiple (>=3) sockets incorporate a 13A fuse, which will provide
overload protection for the spur cable. The second is that fixed
equipment loads of up to 16A are now permitted (using a circuit breaker
of up to 16A instead of the usual BS 1362 fuse). All said then, it would
seem logical to allow multiple items of fixed equipment, provided that
the FLC doesn't exceed 16A, and even the combination of a single socket
and one fixed item of up to (say) 5A.
--
Andy
Ian Clowes
Stefek Zaba wrote:
>
>
> And I meant that you *are* so permitted.
Hi
OK. That's useful to know.
Thanks
IanC
Paul C Lewis
>
> It is recommended that CH systems are powered either from a fused, switched
> connection unit or by an _unswitched_ socket (forcng removal to switch the
> power off). The thinking is that if there were a polarity reversal simply
> switching off at the socket would not be safe.
Of course unless a double pole switch is used, pulling the fuse or
switching off won't protect against a polarity revesal, and there is no
easy option of complete isolation: i.e. pulling the plug out !
--
Paul
Stefek Zaba
> Of course unless a double pole switch is used, pulling the fuse or
> switching off won't protect against a polarity revesal, and there is no
> easy option of complete isolation: i.e. pulling the plug out !
But appliance switches, whether FCUs or unfused 20A switches, are invariably
double-pole. Though I tend to agree that the total isolation offered by
pulling out a plug is particularly reassuring... Where an FCU is used, I
often pull the fuse out while I'm working on the appliance, as another
belt-n-braces against unwanted energisation (few FCUs have any facility
for "locking off"; they're supposed to be sited within sight of anyone
working on the appliance, but that doesn't always happen...)
Stefek