Cable for outside lights?
dmc
My dad has bought a selection of lamps and pir sensors to light up his drive
allyway and porch on his house and he wants me to to help him wire it all
up. I'm fine with the electrics but I am not certain what cable to use.
The outside lights that I have in my garden seem to be wired up with twin
and earth but as they were put in by the previous owner I don't know for
sure (I don't use them anyway having discovered some of the horrors hidden
but that is another story!). This cable appears to be fine and has been
out in the weather (full sun in places) for at least 5 years but it doesn't
seem correct to me.
Checking the FAQ turns up nothing - google finds a few suggestions that
shielded cable is the correct way to go (expensive? And seems overkill!)
or running T+E in conduit (rather not - and may end up looking messy).
What do I really want? I need a couple of m of 3core+earth (to run from the
PIR) and then the rest simple T+E would be ideal if it isn't going to fall
apart as it doesn't need physical protection. Is there such a thing as
"sun proof T+E"? I take it there is not difference between the white
stuff you see in the sheds and the grey cable that seems harder to find
on the high street (apart from the colour obvously :-).
Or should I just run it in T+E and then check it every year - it will be
less exposed than the >5year old stuff that I have and that *looks and feels*
fine....
Opinions? I don't want to spend a fortune on this but I don't want to have
to redo it next year either!
Darren
Stefek Zaba
> What do I really want? I need a couple of m of 3core+earth (to run from the
> PIR) and then the rest simple T+E would be ideal if it isn't going to fall
> apart as it doesn't need physical protection. Is there such a thing as
> "sun proof T+E"? I take it there is not difference between the white
> stuff you see in the sheds and the grey cable that seems harder to find
> on the high street (apart from the colour obvously :-).
To do the job "properly", I'd be tempted to use a decent outdoor-rated cable.
Yes, there are non-armoured PVC insulated cables particularly made for this
job. RS sell them under such stock numbers as 234-118 (3-core, 1.5mmsq),
51quid+VAT for the 100m reel. (Find them online at rswww.com). The trade
name for this cable is "SuperTuff"; it's a circular cross-section, all PVC,
outer black, UV-resistant; inner "matrix" surrounding the conductors of
white PVC, and finally PVC-insulated individual conductors. A little less
flexible than the equivalent conductor-cross-section indoor T&E, but a lot
less hassle than armoured cable.
Being RS, their prices aren't the keenest. Once you know what it is you
want (you may find websearching useful to track down the original supplier)
you can try your local electrical wholesaler, who'll be able to order you
whole reels (at least) and (if you go in at a non-busy time) might do you
a cut length. For a relatively exotic cable like this, try one of the biggies
like C&F (?hope I'm remembering their name right) who are more likely to
have the stuff in stock and be happy to cut off a few meters for you, than
a small corner-shop outfit which would have to order in a minimum quantity.
Rather than ordering an extra bit of 3+E, you could run a second length
to/from the PIR (don't even *think* about using the earth conductor as a
switched-live return. No, seriously, don't. Not even with a bit of red
sleeving over it. The next person to work on your wiring might not be as
bright and cautious as you...)
You could also think about using outdoor *flex*, though strictly speaking
for a permanent installation you should be using solid-core rather'n flex.
H07RN-F and H05RN-F are outdoor-rated cables (also in the Arr Ess catalogue).
Even B&Q warehousen and garden centres sell this, under the name "pond pump
cable", but usually at a pretty hideous price-per-meter...
And then, as you mention, there's the plastic conduit + conduit wire option;
but that might be too visually intrusive for your needs.
Having said all of that, the UV degradation of "indoor" T&E will take quite
a time - I don't think you'd be replacing it all within a year, or even a few.
There are lots of PIRs out there with a loop of 1.5mm or 1.0mm T&E (the
slightly better installed ones even remember to put in a drip loop :-) which
have been in the wind, sun and rain for a good few years and haven't yet
fizz-banged. But you did ask about doing the job to a good workmanlike
standard :-)
Cheers, Stefek
ch...@areti.co.uk
as more robust types especially where it's exposed to sunlight. I'm
generally happy using T&E where it's in the shade and well protected
(e.g. under eaves, clipped to underside of timbers, etc.) but in more
exposed places I've used either armoured cable or T&E in trunking.
Personally I think trunking looks tidier than exposed clipped T&E too.
One problem with using T&E is that most 'outdoor' fittings expect
round cable and it's difficult to effect a waterproof (or even
splashproof) entry with T&E. I therefore generally try and put boxes
in sheltered positions and/or have the cable entry at the bottom.
--
Chris Green (cgr...@x-1.net)
dmc
Stefek Zaba <sj...@hplb.hpl.hp.com> wrote:
>In uk.d-i-y, dmc (D.M.C...@ukc.ac.uk) wrote:
>
>> What do I really want? I need a couple of m of 3core+earth (to run from the
>> PIR) and then the rest simple T+E would be ideal if it isn't going to fall
>> apart as it doesn't need physical protection. Is there such a thing as
>> "sun proof T+E"? I take it there is not difference between the white
>> stuff you see in the sheds and the grey cable that seems harder to find
>> on the high street (apart from the colour obvously :-).
>
>To do the job "properly", I'd be tempted to use a decent outdoor-rated cable.
>Yes, there are non-armoured PVC insulated cables particularly made for this
>job. RS sell them under such stock numbers as 234-118 (3-core, 1.5mmsq),
>51quid+VAT for the 100m reel.
Ouch!
>Rather than ordering an extra bit of 3+E, you could run a second length
>to/from the PIR (don't even *think* about using the earth conductor as a
>switched-live return. No, seriously, don't. Not even with a bit of red
>sleeving over it. The next person to work on your wiring might not be as
>bright and cautious as you...)
Yeah - I was going to use two runs but it just seemed "neater" to do it
with the 3+E :-)
I hadn't (and wouldn't!) even consider using the earth as the switched live.
the previous owner of by house had done that - scary. He had also neatly
chopped the earths that he wasn't using as live back to the insulation -
much easier that connecting them to anything you see. Also, I discovered
a piece of the kitchen ring had been extended with a piece of 1mm lighting
cable. Nice.
As for the horrors of the upstairs sockets thats another tale....
>You could also think about using outdoor *flex*, though strictly speaking
>for a permanent installation you should be using solid-core rather'n flex.
>H07RN-F and H05RN-F are outdoor-rated cables (also in the Arr Ess catalogue).
>Even B&Q warehousen and garden centres sell this, under the name "pond pump
>cable", but usually at a pretty hideous price-per-meter...
Hmmm. Flex might be an option I guess. Is it worth tinning the stripped
cable with solder to make it semi-solid-core or is that likely to make
things worse?
>And then, as you mention, there's the plastic conduit + conduit wire option;
>but that might be too visually intrusive for your needs.
Yeah, I'm not sure mum would approve of this really.
>Having said all of that, the UV degradation of "indoor" T&E will take quite
>a time - I don't think you'd be replacing it all within a year, or even a few.
>There are lots of PIRs out there with a loop of 1.5mm or 1.0mm T&E (the
>slightly better installed ones even remember to put in a drip loop :-) which
>have been in the wind, sun and rain for a good few years and haven't yet
>fizz-banged. But you did ask about doing the job to a good workmanlike
>standard :-)
Having been over the weekend and had a closer look I think I will run T+E
(+ a length of 3+E) back straigt up the walls into the loft. I can then
use a junction box in the loft which should be easier than trying to
wire this lot up at the top of a ladder. Also, having seen the size of the
terminal block in the PIR and the amount of room to work it is going to
be fiddly to say the least. At least this was I can sit in the loft at my
leasure. It also means that most of the cable can be hidden behind downpipes
etc so reducing the amount of sun that they get.
I think I will probably live with the limited life of the T+E for now.
Just need to find a feed in the loft now...
Cheers,
Darren
ch...@areti.co.uk
>
>>You could also think about using outdoor *flex*, though strictly speaking
>>for a permanent installation you should be using solid-core rather'n flex.
>>H07RN-F and H05RN-F are outdoor-rated cables (also in the Arr Ess catalogue).
>>Even B&Q warehousen and garden centres sell this, under the name "pond pump
>>cable", but usually at a pretty hideous price-per-meter...
>
> Hmmm. Flex might be an option I guess. Is it worth tinning the stripped
> cable with solder to make it semi-solid-core or is that likely to make
> things worse?
>
between tinned and not tinned otherwise it flexes there and will in
time fracture adjacent to the tinning.
--
Chris Green (cgr...@x-1.net)
Stefek Zaba
One thing you could do to extend the life of the T&E is to put black
heatshrink over the weather-exposed portion: again, RS and Maplin will sell
you stuff to do the job (in less over-the-top quantities, too: like, a 1.2m
length of 12.7-shrinking-to-as-little-as-6.4-mm-diam black heatshrink is
called part nr 170-6428 at RS and will cost you a massive 2.63 + VAT; if you
want fancy, you can get adhesive-lined, such as 157-3428 at 5.43 for the
1.2m length - this stuff is more suited for external use.
Hope that helps - Stefek
dmc
<ch...@areti.co.uk> wrote:
>dmc <D.M.C...@ukc.ac.uk> wrote:
>> Hmmm. Flex might be an option I guess. Is it worth tinning the stripped
>> cable with solder to make it semi-solid-core or is that likely to make
>> things worse?
>You have to be careful that it can't move at all near the junction
>between tinned and not tinned otherwise it flexes there and will in
>time fracture adjacent to the tinning.
Thats what I was worried about. So, to-tin-or-not-to-tin?
Ho hum. I guess there shouldn't be a lot (any?) of movement so maybe its
a good idea.
Darren
Adrian Brentnall
> dmc <D.M.C...@ukc.ac.uk> wrote:
> >
> > Hmmm. Flex might be an option I guess. Is it worth tinning the stripped
> > cable with solder to make it semi-solid-core or is that likely to make
> > things worse?
> >
> You have to be careful that it can't move at all near the junction
> between tinned and not tinned otherwise it flexes there and will in
> time fracture adjacent to the tinning.
Tinning flex which is going into a screwed connection is a really bad idea!
What can happen is that the lead solder 'creeps' over time (due to the pressure
of the grub screw - eventually this makes for a bad contact, which causes local
heating, which makes the contact even worse... and you end up with a fire.
Same applies to the way some manufacturers 'tin' the ends of their appliance
flexes - it's to make it easy for them during factory testing - and you should
snip off the tinned portions before fitting into your own plug.
Regards
Adrian
Suffolk UK
Dave Plowman
> this job. RS sell them under such stock numbers as 234-118 (3-core,
> 1.5mmsq), 51quid+VAT for the 100m reel. (Find them online at rswww.com).
> The trade name for this cable is "SuperTuff"; it's a circular
> cross-section, all PVC, outer black, UV-resistant; inner "matrix"
> surrounding the conductors of white PVC, and finally PVC-insulated
> individual conductors. A little less flexible than the equivalent
> conductor-cross-section indoor T&E, but a lot less hassle than armoured
> cable.
That's actually somewhat of a bargain compared to TLC's Hituf which is
about twice the price. Congratulations to RS - for once.
--
* Why are a wise man and a wise guy opposites? *
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
Dave Plowman
Stefek Zaba <sj...@hplb.hpl.hp.com> wrote:
> One thing you could do to extend the life of the T&E is to put black
> heatshrink over the weather-exposed portion: again, RS and Maplin will
> sell you stuff to do the job (in less over-the-top quantities, too:
> like, a 1.2m length of 12.7-shrinking-to-as-little-as-6.4-mm-diam black
> heatshrink is called part nr 170-6428 at RS and will cost you a massive
> 2.63 + VAT; if you want fancy, you can get adhesive-lined, such as
> 157-3428 at 5.43 for the 1.2m length - this stuff is more suited for
> external use.
Using heat shrink for this puts the price of the cable per meter well
above the likes of MI. I'd have thought plain black PVC sheathing would be
as good anyway - not that I'd use either. Proper external cable isn't that
expensive.
--
* Never kick a cow pat on a hot day *
Stefek Zaba
> Using heat shrink for this puts the price of the cable per meter well
> above the likes of MI. I'd have thought plain black PVC sheathing would be
> as good anyway - not that I'd use either. Proper external cable isn't that
> expensive.
For a long length, Dave, I agree it's unnecessarily expensive. But given
the original poster's decision to use indoor T&E in a partially-protected
position with just the last foot or so exposed to the full effects of
weathering, an outdoor shrink struck me as a reasonable life-extender. As
I wrote in the earlier response, I'd consider a "proper" job to be the one
using "proper" external cable/flex (and suggested flex as being more
available in cut lengths at retail outlets).
Cheers, Stefek
Stefek Zaba
who do country-wide delivery/mail-order, with a partial www presence), and
noticed that they do a per-meter price on outside cable of the sorts we've
been discussing, such as Hi-Tuff. So, if you want to do the job using the
right stuff, and can't find a local trade counter selling small lengths,
that's one possible source. Add a few junction boxes, switches, and the
like, and soon you'll be denting your credit card enough not to pay a
delivery charge :-)
Stefek
Rick Hughes
always use Butyl rubber insulated cable for all external flex applications.
They also use it for all flex connections to lampholders ... normal PVC
insulated eventually breaks down due to heat of the fitting (except of
florescents )
They also always put a length of colour coded heat resistant sleeving over
all the connection tails.
Rick
Dave Plowman <dave....@argonet.co.uk> wrote in message
news:4ad10d607d...@argonet.co.uk...
Dave Plowman
Rick Hughes <flobb...@virgin.net> wrote:
> Interesting comment yesterday from an Electrical Contractor - they now
> always use Butyl rubber insulated cable for all external flex
> applications. They also use it for all flex connections to lampholders
> ... normal PVC insulated eventually breaks down due to heat of the
> fitting (except of florescents )
I'm not sure where they get 0.5mm 2 core butyl from - I've never seen it
in a wholesaler.
And the plastic lampholder usually breaks up with heat long before the
flex. ;-)
--
* I'm not a complete idiot, some parts are missing *
ch...@areti.co.uk
> Interesting comment yesterday from an Electrical Contractor - they now
> always use Butyl rubber insulated cable for all external flex applications.
> They also use it for all flex connections to lampholders ... normal PVC
> insulated eventually breaks down due to heat of the fitting (except of
> florescents )
>
> They also always put a length of colour coded heat resistant sleeving over
> all the connection tails.
>
heatshrink sleeving to do this with. Although quite how heat
*resistant* it is I'm not quite sure.
--
Chris Green (cgr...@x-1.net)