shower

[tommyl18]

Hi Can I run a 8.5kw shower on a 6mm cable?

 

[ericmark]

Possibly. Cable does not have one rating but a whole range according to type and where run.

It will likely be somewhere between 23.5 and 58 amps. So it like asking can I drive at 70 MPH on a British road.

You need to give a lot more information. 8.5kW = 37A So Reference Method B (enclosed in conduit on a wall or in trunking etc.) or Reference Method C* (Clipped direct) with 70 deg C thermoplastic insulated and sheathed flat cable with protective conductor. Would both be permitted however since one can't buy a 38 A MCB in real terms 6mm only if clipped direct.

 

[tommyl18]

Hi thanks, its flat cable which is clipped direct to the wall and behind the plaster.The cable run to the board is about 8 metres long.

 

[PrenticeBoyofDerry]

Hi thanks, its flat cable which is clipped direct to the wall and behind the plaster.The cable run to the board is about 8 metres long.

Are walls insulated where the cables run and does the cable run in trunking or conduit at any point.
6.00mm flat twin&earth cable can carry a maximum of 47A that is providing there are no dertaing factors to consider.
A 8.5kW shower will require a 37A current.
And as ericmark has pointed out the MCB required would be 40A and any derating factors by either method of installation or route of cable will take the current carrying capacity of the cable down below the one required by the appliance, so the only method that would be suitable, is that of the cable being clipped direct or within the fabric of the building without insulation being present and not routed in conduit or trunking.

 

[ban-all-sheds]

Hi thanks, its flat cable which is clipped direct to the wall and behind the plaster.The cable run to the board is about 8 metres long.

• http://www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  

 

[securespark]

58A on 6 milli?

 

[ericmark]

Yes thermosetting (90 deg C) Reference Method C* (Clipped direct) is 58A but most twin and earth is thermoplastic insulated not thermosetting so I would consider the norm to be 34A that's Reference Method 100# (above a plasterboard ceiling covered by thermal insulation not exceeding 100 mm in thickness) so I would normally think of 6mm twin and earth as 32A cable.

However Ali-Tube to BS 8436 is thermosetting and is designed for going inside walls so we could easy be talking about that cable. I was rather surprised that mineral insulated is just 57A I would have expected it to be higher than Ali-tube not lower. Mind you 1A is not really worth talking about.

 

[securespark]

Sorry, was not considering thermosetting as thermoplastic is by far the more commonly used type.

 

[EFLImpudence]

I'm sure all this is very confusing for the OP.

6.00mm flat twin&earth cable can carry a maximum of 47A that is providing there are no dertaing factors to consider.

I.e. 70° Thermoplastic reference method C (clipped direct and/or buried in masonry).

6mm² ref.method C, 45A mcb, 10.5kW @ 240V shower . Satisfactory.