10kW Shower

[daz3770]

hi there,

I have been trying to find a definate answer to a problem. I have a 10kW shower that should draw 43.5A. I have read on another site that this will need 16mm cable. I also read that 10mm cable is rated to 53A. Please can anyone clear up these issues.

Kind regards

 

[RF Lighting]

There is not set rating for a particular size of cable.

It's safe current carrying capacity is determined by factors such as the length of run, wether the cable is burried direct into plaster or run in conduit, trunking, thermal insulation, the ambient temperature of the route, etc.


Please provide us with as many details of how the cable will be run from the CU to your shower position.

 

[daz3770]

thanks for prompt reply.

the cable is no more 10m in length and runs mainly through the loft space on the beems under the insulation, this can be moved if necessary. There is a maximum of 1m under plaster. The ambient temp i would say is normally 15-20 degrees.

Hope this is all the info you need

Kind regards

 

[RF Lighting]

You need to get the cable up and out of the insulation.

even 500mm of cable in thermal insulation requires you to derate its current carrying capacity by 50%


If you can clip the cable so it is not in contact with the insulation then 10.0mm² cable will be sufficient.

 

[daz3770]

Many thanx for your time RF.

 

[davelx]

You need to get the cable up and out of the insulation.

even 500mm of cable in thermal insulation requires you to derate its current carrying capacity by 50%


If you can clip the cable so it is not in contact with the insulation then 10.0mm² cable will be sufficient.

OP says cable is "under" the insulation, not buried in it.

Sheathed cable above thermally insulated ceiling with cable in contact with thermally conducting surface - ie the ceiling (see footnote to Ref Method 4) is Installation Method 15 (table 4A1).

Current capacity of 10mm T&E method 15 is 47A (table 4D5A)

All other derating factors being lower or equal, 10mm is OK and use a 45A MCB

 

[daz3770]

Dave,

Please can you tell me where to find the information in your refs. They dont make sense to me.

Regards Darran

 

[Spark123]

The info he is referring to is in BS7671 (aka the IEE regs) and in the On Site Guide.
By the sounds of it you are installing a new circuit, please also read up on part p.