downlighters... fire worry!

[TopTrumper]

GaryMo
lets get one thing straight.
If i was designing circuits from scratch and money was no issue, showers and cookers would be installed in 10mm cable everytime, and probably LS0H cable, and also, every circuit would be protected by its own crabtree RCBO.

But i live in the real world, unlike you pair of muppets, would not install a shower 9 feet away from consumer unit in 10mm cable? never heard of anything so pathetic, even the manufacturers say 10mm only.

 

[GaryMo]

I'd love to the list of departures on one of your EIC's though I doubt any would comply with 120.3 or 120.4.

Did you send a letter to PE magazine recently?

 

[Spark123]

But i live in the real world, unlike you pair of muppets, would not install a shower 9 feet away from consumer unit in 10mm cable? never heard of anything so pathetic, even the manufacturers say 10mm only.

Sorry - I don't follow what you are trying to say in this statement. If the manufacturer advises the use of 10mm and the regs advocate the use of 10mm then why use anything else?

An 8500w shower has a design current of 8500/230 = 37A (rounded up). This will require a 40A MCB as a minimum. The installed cable needs to have a current carrying capacity of greater than 40A.
BS7671:2008
For a clipped direct flat twin and earth cable table 4D5 - 6mm has a CCC of 47A and 10mm has a CCC of 64A. For a cable run in 100mm of insulation the CCC of the cable needs to be reduced, from table 52.2 a factor of 0.78 is given hence the CCC of 6mm becomes 36.6A and 10mm becomes 49.9A. This does not take into account any other correction factors.
BS7671:2001 inc amd1&2
From table 4D5A for M1 the CCC of 6mm is 47A and the CCC of 10mm is 64A. From table 52A the CCC needs to be reduced by a multiplying it by a factor of 0.81 hence the CCC of 6mm will be 38A and 10mm 51A. This also doesn't take into account any other correction factors.

From the above, 6mm is not a suitable cable size where a cable it to be run through 100mm of insulation and protected by a 40A OCPD. It isn't suitable under the 17th edition and wasn't suitible in the 16th edition regs either.

 

[Chri5]

But i live in the real world, unlike you pair of muppets, would not install a shower 9 feet away from consumer unit in 10mm cable? never heard of anything so pathetic, even the manufacturers say 10mm only.

You need to take a check on your attitude, both to the people here and (if you are a spark) to your paying clients.

Just because a manufacture suggests 10mm how can that ever be fixed in stone?

A 4 storey house with CU on the base level, a shower on the top floor and some 'interesting' cable routes could run to 25m from the CU.

So that's within 10mm tolerance for a 45a load is it ?

You are making yourself look daft. Why not accept that your wrong and attempt some humility

 

[mkb]

blummin, flippin 'eck !!! What have I started ?

 

[GaryMo]

It's not your fault, blame TopTrumper for the unwanted hijack.
I'm sorry for my part in it but I was merely defending my corner after the stupid comment he made in the forth post on page 1.

Anyway, I hope you got the answers you wanted.

 

[tSpark]

like, are you planning to grow things in my attic???

"No love, its for the earth electrode"

P.S. Anyone know why I can never get a decent Ze on a TT?

Untitled

• tSpark
• 16 Nov 2008
• 1

 

[sparkyspike]

I thought TopTrumper was already aware about using the wrong cable size....

//www.diynot.com/forums/viewtopic.php?p=254018#254018

 

[sparkyspike]

And worryingly...

fellas,
im a spark by trade and fit a lot of electric showers.

 

[GaryMo]

And worryingly...

fellas,
im a spark by trade and fit a lot of electric showers.

 

[tSpark]

never heard of anything so pathetic, even the manufacturers say 10mm only.

The manufacturer might say 10mm terminations only, but I can really assure you the manufacturer would not say, contravine BS7671 and all common sense to feed this shower with a 10mm cable, even when because of its method of erection it cant carry the load necessary to run it. Thats Pathetic Mate

 

[david_uk]

Ignoring the flying handbags, to get back to the original question:-

Have a read of the manufacturers instructions for the luminaire. They often will have specific instructions as to how far the insulation has to be removed. Also, bear in mind that if you cut into a plasterboard ceiling you may be breaking a fire barrier, so it might be an idea to fit fire rated downlighters, or use a smoke hood.

 

[GaryMo]

Also, bear in mind that if you cut into a plasterboard ceiling you may be breaking a fire barrier, so it might be an idea to fit fire rated downlighters, or use a smoke hood.

A loft above a bedroom? Do you have shares in a company that produces smoke hoods?

Seriously though, I always use fire rated fittings as standard. I find their construction superior to open backed fittings.
At £6.50+VAT for JCC 90 minute downlighters they're not priced too badly either.

 

[david_uk]

A loft above a bedroom? Do you have shares in a company that produces smoke hoods?

Nope, but I DO have a loft above a bedroom Our house was a bungalow until we converted the loft about 5 years back. We raised the pitch of the roof by about 2 metres to give wider rooms, and the benefit of this was we had a loft again! We call it the loft loft. I know - we need to get out more

 

[GaryMo]

We call it the loft loft.