Shower circuit 10mm

[ultinator]

Was reading an older thread and dont have any books to hand, but basically.

If a cable for a 10kw shower is to be run, the current drawn would be 43.4 A.

So if 6mm cable was appropriate for say 70% of the run that was clipped direct, but not suitable for 30% of the run due to de-rating factors, as it would be covered by insulation . Could you size up to a 10mm cable just before the cable hit the insulation part of the run, the drop back to 6mm after the insulation where it may be clipped direct again.

I would like to note that this a hypothetical question, and the thought behind it was that if you had a long run then being able to buy only 30% of the run in 10mm would save you monies on cables.

Also (on a separate note) with gu10 firerated lights is there a recommended clearance of insulation from around them i.e. in a loft where the lights come up from ceiling below, as I presume you would want as much insulation to remain as possible.

Hope that all makes sense, thanks.

 

[sparks1973]

well thats just like suggesting that volt drop isn`t a factor......jesus..lol...

 

[trev]

Imho yes. You have designed properly and installed, inspected and tested to 7671 and have copies of the paperwork to prove it. Mr Insulation comes along with his ignorance and screws everything up.
I'd say that ignorance of our regs is no excuse, after all we're supposed to be aware of all building regs so why shouldn't he?

 

[Silly Sausage]

.....one more thing ha, if you were to design a circuit with all things considered and no insulation around any cable, then mr ecosulation man comes and dumps a crap load of insulation on your cable thereby severely underrating it and a fire starts would he be solely liable and responsible?

Normally I would say, if your install complies at the time you did it, no problem, you can't be held responsible for what happens to it in the future.
But...if you were laying cables in an uninsulated attic on the ceiling below (you know what I mean!), for example, there is a good chance that cables would be covered over in the near future, especially with these free loft insulation offers going. Had mine done for freebies a couple of years ago.

 

[telectrix]

quite right. would he pile a foot of fibreglass on top of the kitchen hob, or cram it roung the C/H boiler. ... NO. so why should the muppet treat our installations with such disrespect.

 

[tigerpaul]

If you can reasonably foresee a situation where thermal insulation could compromise the integrity of your installation, then you should take the appropriate course of action to protect the electrical system.

 

[sparks1973]

quite right. would he pile a foot of fibreglass on top of the kitchen hob, or cram it roung the C/H boiler. ... NO. so why should the muppet treat our installations with such disrespect.

because he`s a `green industry` muppit...or is that puppet?..

 

[Guitarist]

So much easier to keep cables above the insulation in a loft, then take them through the insulation in oval conduit. Saves a lot of worry.

 

[telectrix]

If you can reasonably foresee a situation where thermal insulation could compromise the integrity of your installation, then you should take the appropriate course of action to protect the electrical system.

good thinking. a 12 bore in the attic with a piece of string attached to the hatch. that should sort it.

 

[Guitarist]

good thinking. a 12 bore in the attic with a piece of string attached to the hatch. that should sort it.

That's fine tel, until you remember you left a screwdriver up there.....

 

[telectrix]

then again, in a house less than 40 yrars old, it would probably collapse the roof trusses,, explode the water tank that the kind plumber has placed in the only space that you can crawl through, bonus free sprinkler system.

 

[sparks1973]

then again, in a house less than 40 yrars old, it would probably collapse the roof trusses,, explode the water tank that the kind plumber has placed in the only space that you can crawl through, bonus free sprinkler system.

yes...complete with walls made up out of thermalite...and floors like a trampoline....