Running cables and cenrtral heating pipes.

[joe-90]

I want to run some cables under the floor in voids that are shared with central heating pipes.

I've got a copy of the regs but can't find any correction factors.

Big Spark says he works it all out so I wondered if he might direct me as to where in the regs I'd find the formula.

 

[RF Lighting]

It is in appendix 4, section 7.1

(saves me typing it out )

 

[ricicle]

Expected ambient temperature of floor void.Factors for ambient temp are abbreviated as Ca and off the top of my head table 4C1.
Multiply cable rating by correction factor for new rating in void.

 

[joe-90]

Yes I have a copy but it doesn't really say anything - just a rather large equation. So how does that work?

 

[ricicle]

Expected ambient temperature of floor void.Factors for ambient temp are abbreviated as Ca and off the top of my head table 4C1.
Multiply cable rating by correction factor for new rating in void.

 

[joe-90]

Can I just clear something up? In thread near this one a guy is asking about insulation in his shed and the advice is that his electrician should take into account a bit of loose insulation, yet the advice that I may install cables near hot pipes isn't important?

How can this be?

 

[ricicle]

Expected ambient temperature of floor void.Factors for ambient temp are abbreviated as Ca and off the top of my head table 4C1.
Multiply cable rating by correction factor for new rating in void.

 

[joe-90]

In other words you cannot answer.

 

[ricicle]

In other words you cannot answer.

What more would you like me to do

 

[RF Lighting]

Sorry, ignore my first reply, I've just realised that relates to volts drop rater than current carrying capacity.

As ricicle said table 4C1 is what you want.

 

[joe-90]

So how do you measure this ambient temperature? (bearing in mind that most sparks run the cables in the same notch as the heating pipes?)

 

[securespark]

Most sparks do not!

Builders and Bodgers may, but proper sparks do not.

 

[ricicle]

Thermometer, pyrometer, pipes at full operating temp.Allow void to reach maximum temp and measure.
Say its 40°c then I think its around 0.87 for PVC so a 100Amp rated cable would be de-rated to 87 Amps in this scenario.

 

[ricicle]

Are you trying to test the integrity of someone on here Joe-90?