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Extension lead safety in garden?
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jim
Jul 1, 2013, 2:11:41 PM7/1/13
to
Please, what is current opinion on use of extension leads in the garden?
Focus of attention is a 650W electric hedgecutter plugged via a 30m extension lead into a 13A socket on a house 30A ring MCB/RCD protected circuit. The supply is PME if that is relevant. The hedgecutter is double insulated & its lead has only L & N cores - ie no earth, though the extension lead does carry an earth conductor. The extension cable is rated 10A, fully unwound - 3A reeled up.
So to get to the point: how well protected is the user from electric shock?
Are things improved or made worse by inserting one of those plug-in RCDs which are often advocated for portable appliances? & if improved, where should the RCD device be inserted - ie at the house socket or at the end of the extension lead?
TIA for any views.
Focus of attention is a 650W electric hedgecutter plugged via a 30m extension lead into a 13A socket on a house 30A ring MCB/RCD protected circuit. The supply is PME if that is relevant. The hedgecutter is double insulated & its lead has only L & N cores - ie no earth, though the extension lead does carry an earth conductor. The extension cable is rated 10A, fully unwound - 3A reeled up.
So to get to the point: how well protected is the user from electric shock?
Are things improved or made worse by inserting one of those plug-in RCDs which are often advocated for portable appliances? & if improved, where should the RCD device be inserted - ie at the house socket or at the end of the extension lead?
TIA for any views.
Fredxx
Jul 1, 2013, 2:29:51 PM7/1/13
to
safe as it's going to be.
At one time I thought you could get plug-top 10mA RCDs, or was I just
dreaming?
Andrew Gabriel
Jul 1, 2013, 3:22:43 PM7/1/13
to
In article <kqshgm$427$1...@dont-email.me>,
Without an RCD, the earth fault loop impedance can be an issue.
PAT test guidelines for extension leads with 13A fuse:
1.25mm² 12m max length
1.5mm² 15m max length
2.5mm² 25m max length (won't fit in most 13A plugs though)
They mustn't be daisy-chained to longer lengths.
By fitting a lower current fuse, you could in theory increase
the cable length proportionally. The RCD removes the concern over
earth fault loop impedance, but you may in theory end up with a
short on the cable which takes long enough to blow the fuse that
the cable gets damaged.
I have a dedicated outdoor socket circuit, and that's on a 10mA
RCBO in the consumer unit. After a couple of accidents, I had to
replace the hedge cutter flex anyway, and so I used 3-core, but
the earth is not connected at the hedge cutter end. However,
having it in the cable seemed to me like a good thing, as it
increases the chance of an earth fault if the cable is cut (thereby
tripping the RCD), and reduces the chance of the earth fault going
through me whilst I'm balanced at the top of a ladder. I have
managed to cut through the lawnmower cable without blowing a fuse
or the RCD (probably too quick), leaving a live cable-end in the
garden. I suspect that if I had the earth in the cable too like
I do on the hedge cutter, that might have tripped the RCD.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
PAT test guidelines for extension leads with 13A fuse:
1.25mm² 12m max length
1.5mm² 15m max length
2.5mm² 25m max length (won't fit in most 13A plugs though)
They mustn't be daisy-chained to longer lengths.
By fitting a lower current fuse, you could in theory increase
the cable length proportionally. The RCD removes the concern over
earth fault loop impedance, but you may in theory end up with a
short on the cable which takes long enough to blow the fuse that
the cable gets damaged.
I have a dedicated outdoor socket circuit, and that's on a 10mA
RCBO in the consumer unit. After a couple of accidents, I had to
replace the hedge cutter flex anyway, and so I used 3-core, but
the earth is not connected at the hedge cutter end. However,
having it in the cable seemed to me like a good thing, as it
increases the chance of an earth fault if the cable is cut (thereby
tripping the RCD), and reduces the chance of the earth fault going
through me whilst I'm balanced at the top of a ladder. I have
managed to cut through the lawnmower cable without blowing a fuse
or the RCD (probably too quick), leaving a live cable-end in the
garden. I suspect that if I had the earth in the cable too like
I do on the hedge cutter, that might have tripped the RCD.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
polygonum
Jul 1, 2013, 3:41:39 PM7/1/13
to
On 01/07/2013 20:22, Andrew Gabriel wrote:
> I have a dedicated outdoor socket circuit, and that's on a 10mA
> RCBO in the consumer unit. After a couple of accidents, I had to
> replace the hedge cutter flex anyway, and so I used 3-core, but
> the earth is not connected at the hedge cutter end. However,
> having it in the cable seemed to me like a good thing, as it
> increases the chance of an earth fault if the cable is cut (thereby
> tripping the RCD), and reduces the chance of the earth fault going
> through me whilst I'm balanced at the top of a ladder. I have
> managed to cut through the lawnmower cable without blowing a fuse
> or the RCD (probably too quick), leaving a live cable-end in the
> garden. I suspect that if I had the earth in the cable too like
> I do on the hedge cutter, that might have tripped the RCD.
Glad you wrote that. I cannot get my head to believe that two cores are
> I have a dedicated outdoor socket circuit, and that's on a 10mA
> RCBO in the consumer unit. After a couple of accidents, I had to
> replace the hedge cutter flex anyway, and so I used 3-core, but
> the earth is not connected at the hedge cutter end. However,
> having it in the cable seemed to me like a good thing, as it
> increases the chance of an earth fault if the cable is cut (thereby
> tripping the RCD), and reduces the chance of the earth fault going
> through me whilst I'm balanced at the top of a ladder. I have
> managed to cut through the lawnmower cable without blowing a fuse
> or the RCD (probably too quick), leaving a live cable-end in the
> garden. I suspect that if I had the earth in the cable too like
> I do on the hedge cutter, that might have tripped the RCD.
better than three. Maybe hardly any worse. Surely much of the
double-insulated concept is about saving costs not enhanced safety? You
could have all the protective aspects of double-insulation and still
allow a cable to terminate with three connections within a device.
--
Rod
Dave Liquorice
Jul 1, 2013, 3:33:02 PM7/1/13
to
On Mon, 01 Jul 2013 19:29:51 +0100, Fredxx wrote:
> If the circuit has an RCD, and it's been tested recently, then it's as
> safe as it's going to be.
Agreed, test the RCD that covers the circuit in question with its
> If the circuit has an RCD, and it's been tested recently, then it's as
> safe as it's going to be.
test button. Remembering that everything else also fed through that
RCD will also go off...
> At one time I thought you could get plug-top 10mA RCDs, or was I just
> dreaming?
long extension cable attached, the inrush can trip it...
--
Cheers
Dave.
ARW
Jul 1, 2013, 4:41:24 PM7/1/13
to
--
Adam
Road_Hog
Jul 2, 2013, 7:24:47 AM7/2/13
to
"ARW" <adamwa...@blueyonder.co.uk> wrote in message
news:kqsp7m$4ud$1...@dont-email.me...
>
> Petrol strimmers are the new garlic bread:-)
>
> --
> Adam
>
They may be, but they will be about as useful as garlic bread, as the OP is
> Petrol strimmers are the new garlic bread:-)
>
> --
> Adam
>
attempting to cut a hedge.
Jaffna Dog
Jul 2, 2013, 8:10:36 AM7/2/13
to
On Monday, 1 July 2013 19:11:41 UTC+1, jim wrote:
> Please, what is current opinion on use of extension leads in the garden?
>
>
>
> Focus of attention is a 650W electric hedgecutter plugged via a 30m extension lead into a 13A socket on a house 30A ring MCB/RCD protected circuit. The supply is PME if that is relevant. The hedgecutter is double insulated & its lead has only L & N cores - ie no earth, though the extension lead does carry an earth conductor. The extension cable is rated 10A, fully unwound - 3A reeled up.
>
>
I don't trust plug-in RCD's, or the ones built in to sockets, I've known both to fail to trip. The best solution is to protect all circuits with a proper fixed RCD, this also applies to indoor use, with the ever-increasing use of mains-powered gizmo's, many of them with dubious safety.
> Please, what is current opinion on use of extension leads in the garden?
>
>
>
> Focus of attention is a 650W electric hedgecutter plugged via a 30m extension lead into a 13A socket on a house 30A ring MCB/RCD protected circuit. The supply is PME if that is relevant. The hedgecutter is double insulated & its lead has only L & N cores - ie no earth, though the extension lead does carry an earth conductor. The extension cable is rated 10A, fully unwound - 3A reeled up.
>
>
For outside extensions, I've fitted all our power tools and garden machines with 'commando' plugs, with a socket on the extension lead and a short adaptor lead for use indoors. These provide much better protection against water.
Rick Hughes
Jul 2, 2013, 3:29:27 PM7/2/13
to
hedge trimmer ... and up to 9 foot extension.
Great bit of it and push button start - never fails - instant.
Dave Liquorice
Jul 3, 2013, 4:12:17 AM7/3/13
to
On Tue, 2 Jul 2013 05:10:36 -0700 (PDT), Jaffna Dog wrote:
> I don't trust plug-in RCD's, or the ones built in to sockets, I've known
> both to fail to trip.
Do you mean the one feeding just the extension has failed to trip
> I don't trust plug-in RCD's, or the ones built in to sockets, I've known
> both to fail to trip.
when on upstream with other circuits has? Think about it and it's
obvious why that is frequently the case.
> The best solution is to protect all circuits with a proper fixed RCD,
in the consumer unit, part fo the socket used or a plugin one. Don't
like the idea of something happening outside disconnecting stuff
inside without warning.
--
Cheers
Dave.
Jaffna Dog
Jul 3, 2013, 7:52:09 AM7/3/13
to
On Wednesday, 3 July 2013 09:12:17 UTC+1, Dave Liquorice wrote:
> On Tue, 2 Jul 2013 05:10:36 -0700 (PDT), Jaffna Dog wrote:
>
>
>
> > I don't trust plug-in RCD's, or the ones built in to sockets, I've known
>
> > both to fail to trip.
>
>
>
> Do you mean the one feeding just the extension has failed to trip
>
> when on upstream with other circuits has? Think about it and it's
>
> obvious why that is frequently the case.
>
>
No, I mean physically jammed, and not tripping when the test button is pushed.
> On Tue, 2 Jul 2013 05:10:36 -0700 (PDT), Jaffna Dog wrote:
>
>
>
> > I don't trust plug-in RCD's, or the ones built in to sockets, I've known
>
> > both to fail to trip.
>
>
>
> Do you mean the one feeding just the extension has failed to trip
>
> when on upstream with other circuits has? Think about it and it's
>
> obvious why that is frequently the case.
>
>
ARW
Jul 3, 2013, 1:00:56 PM7/3/13
to
And this is me pissed up using it for the first time
http://www.youtube.com/watch?v=6TtGQNvuovE
--
Adam
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