Any Sparkies? Lighting circuit question...

[Andy Clap]

I'm sticking wires in for the first-fit electrics for my kitchen.  The lights will be 12 x 40w recess spots (or LED, haven't decided yet), and a couple of accent lights.  This is on it's own circuit to the consumer unit.


Will 1mm cable be okay (which I have) or should I "future-proof" with 1.5mm (which means downing tools to go and get some)?


Cheers,
Andy

[AdieR]

By my reckoning, you'll have between 2 and 3 amps on that circuit, so 1mm will probably suffice (assuming you haven't got extremely long cable runs), (I stand corrected if anyone knows better).

[Andy Clap]

Thanks Adie, that's what I thought.
Cheers,
Andy

[VNA - BMW Wank]

I always prefer 1.5mm myself, it's a bit more robust.  Keeps temperature down too.  So less need to worry about bunching cables and burying in insulation.

1mm cable I think allows 1200 watt and 83meter run (without switch run, no bunching and above insulation)  That's what a quick google says anyway.

I'd do two circuits for those, 480 watt is quite a bit for lighting.

I've got 11 down-lighters in my kitchen dining room.  They were there when I bought the place.  Didn't think about it till one blew.  Popped it out and it was rated 50w.  So that's 550 watt!  I replaced the lot with Philips EcoHalo downlighters 35w and 25w  -  equivalent to 50 and 35w.

LED is the way, once it becomes affordable for down-lighters.

[BBROWN1664]

Led bulbs as a straight rePlacement for GU10's can be had for £2.50 these days

I would go for 1.5mm as someoneay plug in 100w bulbs later.

[SteveH41]

1.5mm nowadays for general lighting arrangements in a domestic property.

Question

Is there living accommodation above? remember to use fire rated downlighters not the cheapo B&Q specials, visit a reputable wholesaler such as Newey & Eyre / Edmundsons etc as you will get better gear.

I avoid LED at the moment, too many problems with the drivers packing up, Personal choice is a 35 or 50w dichroic unit and appropriate transformer, remember to give sufficient breathing space for the transformers when in the void.

Remember that all the work you are doing is notifiable and comes under Part P of the building regs, either inform building control for them to inspect or employ a Part P approved contractor to carry it out.

Steve.

[esetest]

maximum current carrying capacity for a 1mm cable reference method c  is 13.5 amps , so depending on how many other lights are on the circuit  you should be ok with 1mm , as the work is in a kitchen which is a special location so is notifiable , before altering the circuit you also need to make sure the circuit is protected by an rcd with 30mA protection , and the equipotential earth  bonding to the gas & water pipes is at least 10mm , i would recommend jcc  fire rated downlights as the lamps aren,t exposed , and are less likely to be a hazard if combustible material is nearby .  if you are involving building control they will want to see a certificate .
if your kitchen burnt down , and your asked if you have had any electrical work done and cannot produce a certificate , the insurance company may not pay out or reduce the payment .

[VNA - BMW Wank]

LED's that can put out a decent amount of light are still quite expensive - around 30 quid each compared to 3 or 4 quid for the best quality energy saver halogens.  Also last time I looked LED's have quite a narrow beam.   Hopefully LED's will improve in performance and price in the next few years.

I do find it quite amusing that incandescent lamps of 60w and above have been banned while hopelessly inefficent down-lighters are being fitted left right and centre.  I did think of getting rid of mine as 60watts of ordinary energy saving bulbs would do what the 550w of downlighters would.   But the light qulaity is so much better and welcome in a kitchen environment. 

Remember that all the work you are doing is notifiable and comes under Part P of the building regs, either inform building control for them to inspect or employ a Part P approved contractor to carry it out.

That depends where you live.  Not applicable in Scotland unless it's part of a planning application.

But anyway, nobody I know bothers with 1mm these days.

[VNA - BMW Wank]

maximum current carrying capacity for a 1mm cable reference method c  is 13.5 amps

Is it not 10 amps?  1.5 15amps?  I dunno.

Then you have voltage drop per metre, as well further possible drops/heat for bunching and burying in insulation.

A lighting circuit is protected by a 5 amp fuse (if you still have these you really should upgrade) or 6amp breaker (plus RCB if you wish to upgrade to meet 17th edition regs.) 

I rewired my house and went for 1.5mm cable for the lighting and kept the circuits well within 1200 watt max possible (in reality two circuits the bigger is up to about 600watt max).  As I've got tall ceilings and a few chandeliers (ooh err I know) I wired it up junction box style (ceiling roses don't work with hanging lights) and I didn't want to worry about bunching or insulation calculations.   With 1.5mm you really shouldn't ever be able to stress the cable on a conservatively designed 6 amp circuit.   Plus I just don't like the feebleness of 1mm on terminations personally. 

Oh I'm not a spark, I'm an Inst Tech, but basic industrial electrical installation is part of my job. 

Assuming a suitably qualified and competent person is finishing or checking your work, that person is really the person you should check with if you have any questions before you start wiring up.

It's really quite simple, but asking a variety of different people might make it complicated! 

[Andy FZS]

Takes me back to my colledge days, I still remember the tune but some of the words escape me these days
Andy

[phil on a fazer]

, remember to give sufficient breathing space for the transformers when in the void.

when i bought my house the landing, stairs and bathroom had 12v spots.....one by one they all packed up. I've replaced the bathroom with 240v spots but aint got round to the stairs/landing yet.
 
The transomers were under the attic boards with insultaion...wonder if this is why they died???

[SteveH41]

Could be. Also the lamp holders burn up with use internally and make poor contact. Cheap transformers possibly . Like the jcc stuff. Works and lasts quite well.

[philshaq]

When I re-wired my house I put 1.5mm in for all the lighting. Insulation bury is one consideration but the regulations indicate that provided it is nailed back to a joist its OK for usual load. 1.5mm will be under less strain compared to 1mm and for the extra cost its worth it. Nice and easy to work with as well.


I'd always use 240v lights as well, its easier to wire and a LOT cheaper!


Happy sparkin'

[SteveH41]

the problem with GU10 230v lamps is that they don't give the same quality of light as a 12v Dichroic, I have installed many of both and the preference is 12v anyday of the week, brighter and cleaner looking light. Just about to ripout someones GU10 fittings and replace them with 12v JCC fireguards in a kitchen. The builder / spark / kitchen fitter / gas man (jack of all master of ............) installed non-fire rated units in a kitchen with living space above.... tut tut........

[pitternator]

it always makes me laff that folk who flout regulations when it suits them, are usually the ones who spout off  about others doing such on other threads, and tutt tutt profusely.
 
Its illegal to install electrical circuits in kitchens and bathrooms unless you are part P qualified...so why do folk keep doing it ?...the very fact one is not sure about even what size cable to use is surely enuff cause to get  qualified people to do it...let alone the consequences of  a fire because of the risk of incorrect installation .Recessed lights look great but the sheer proliferance of them now and the heat they create means great care needs taking in their installation. The old electrical regs were designed for kitchens with a single centre light and maybe a couple of fluorescant ( low heat) under cupboard lights.That was easy enuff for most DIY back then....but its way diffrent now.
 
I cant see any insurance company paying out for damage caused by any illegal installation ! ... so is it worth it ??...I spose same folk fit their own gas, fit their own boilers...all well and good till it all goes pete tong.

[VNA - BMW Wank]

Its illegal to install electrical circuits in kitchens and bathrooms unless you are part P qualified...

Firstly that depends where you live.

Secondly, even if you required to be signed off on the 17 edition regs to sign off an electrical installation, you don't have to have any qualification to actually do the installation.  But you do need to get it right, as nobody will sign it off unless it's spot on.

Here's another way of looking at it.  I bought a house, and after poking about it I came to the conclusion that the electrics required immediate attention as they posed a serious risk to my safety.  I won't bore you with the long list of serious faults.   Yet the surveyor scored the condition of the electrics 1. - good condition, no repairs required.  The kitchen had been re-wired, was on it's own circuit and was fine, but the rest of the house required pretty much a full re-wire ASAP.

The house I sold scored 2 - requires attention.  In the house I sold the electrics were in 100% perfect condition, the only shorting coming was a fuse box rather than a modern RCB consumer unit (wired up 1986).  I should have insisted on the correct rating of 1.  Or maybe done a quick DIY job on the consumer unit 

Many folks told me it was illegal for me to rewire my house and told me I'd have to employ a 17th edition spark.  But apparently it was perfectly legal for me to continue to live in a house that was ready burn itself down.  As I do light industrial electrical installation anyway I wasn't too keen on employing a domestic spark.  I bought an idiots 17th edition guide to house wiring - just to gen up on circuits allowed, protection physical and electrical required in a domestic environment, where I could sink sockets etc etc  Further research also told me that contrary to what many had told me, I only needed to inform building control if the installation formed part of a planning application. (this depends where you live)

There are plenty of condensed 17th edition guides for domestic installation and detailed guides for DIY house rewires.  If you required a certificate speak to 17th edition signed off spark before you begin.   If you haven't got a clue, don't understand the guides, can't figure out how to draw up working circuits, then don't do it. 

If your house still has a fuse box, you really should give consideration to upgrading it to a modern RCB consumer unit in the very near future.  Make sure your spark tests all circuits before fitting it.   And I don't recommend DIYing the consumer unit, get a 17th edition spark in to do it (it shouldn't be expensive in most cases) and get a receipt and test certificate.  The protection offered by modern consumer units is impressive, the protection offered by fuses is almost non-existent.

Oh and do ask for recommendations before employing a spark, there's sparks out there I wouldn't trust to put a plug on a kettle, never mind rewire a house.

Even if you don't want to tackle any of the actual wiring you can save a few bob sinking sockets, raggling walls etc ready for your spark.

[SteveH41]

I am electrician by trade - C&G 2382 / 2391 / 2377 pt 2 / 236 parts 1,2 and C.