shower cable capacity

[3rdoldtimer]

Hi can anyone tell me the capacity of electric cable ? The shower cable to my shower is approximately 13mm x 7mm this the overall measurement of the twin and earth cable leading to the consumer unit. I've a 7 kw shower and would like to know if I can use a higher wattage shower on the cable that there.

 

[viewer]

Here's one made earlier:
//www.diynot.com/forums/viewtopic.php?t=23580

 

[3rdoldtimer]

Thank for the quick reply viewer I think it answers my question

 

[EFLImpudence]

Here's a better one -
//www.diynot.com/wiki/electrics:cable_types:flatpvccables

You also have to consider whether the cable runs through thermal insulation or conduit which will reduce the Current Carrying Capacity of the cable.

 

[3rdoldtimer]

Thanks EFLImpudence just took a peek, my cable is about 12 meters long and most of it in the wall. Just seen that multi strands take less amps than single strand, must be less copper overall, Anyway would you be happy with a 9 kw shower on that cable?

 

[Chri5]

What fuse supports the cable at the moment?

 

[EFLImpudence]

my cable is about 12 meters long and most of it in the wall.

If you mean buried in masonry, that's fine.
In a stud wall with insulation, then NO.

Just seen that multi strands take less amps than single strand,

6mm² will be stranded.

Anyway would you be happy with a 9 kw shower on that cable?

If 6mm² is buried in masonry and/or in the open then yes.

What size fuse or mcb is on the circuit and is it protected by a 30mA RCD?
You will need a 40A fuse/mcb

Some old fuse boards won't take a 40A.

 

[3rdoldtimer]

Just looked at the fuse box which was new three years ago, don't understand the fuses so not going to touch them. but the shower trip switch has MBD B32 writen on it the same as the cooker switch. do the 32 mean 32 amps or is it a code.

 

[EFLImpudence]

Yes it means 32A.

You will need a higher one for a larger shower but you must ensure the cable will be safe, as above.

 

[3rdoldtimer]

Thank for that infro EFLImpudence much appreciated, It means I'll stick with the 7.1/2 killowatt. Not worth changing everthing with money being tight.Thanks for your efforts on putting me straight

 

[Chri5]

Thank for that infro EFLImpudence much appreciated, It means I'll stick with the 7.1/2 killowatt. Not worth changing everthing with money being tight.Thanks for your efforts on putting me straight

You could update the fuse, unless my math is poo you should be able to carry 40 amps on the cable, at a push 45 amp.

Not that you could do that yourself, but I'm sure a friend recommended spark would be in and out in less than an hour. Since the job is recent, I'd assume all the bonding and the rest of the system is bang up to date. So you know there's nothing else to pay for.

By the sounds of it your house isn't over run with kids, so no 9 x 20 minute constant showers a day in your house.

Get a bigger shower, look at Screwfix or TLC for best price, and then if you want to buy local you have a price to nibble them down to.

Gas heated water is cheaper than electrically heated, so could you dump the electric shower and go via ch system? Most combi boiler have a decent head for showers now.
If you have stored hot water, then an electric pump does the trick if the pressure is rubbish.

 

[Chri5]

I'll give the mods a knock