extras

[Jackflash]

hi,

Customer with an extension being built wants extra shower, cooker, several sockets, lights installed on seperate consumer unit. The house is 10 years old and has a 12 way consumer unit already serving typical domestic circuits already including power shower, range cooker, water heaters, large amount of sockets and lighting etc. Is it expected that this would overload the 80A main fuse? request supplier to install additional cut out? Any thoughts appreciated thanks!

 

[Hawk81]

It would be hard to imagine that everyting would be on at the same time. Diversity would have to come into play here. I can't see them drawing more than 80 amps.

 

[Jackflash]

Yea i see, Could just something like a be a b50 and 16mm swa. Thanks

 

[SKY]

Still pretty close IMHO.
If the main feed is 80a and they already have an electric shower and a range cooker and wants to also add another shower, cooker and lots of sockets.

Only take 2 people having a 10.5 kw shower whilst the wife is doing the Sunday dinner.

If they are building a nice new extension it must be worth adding capacity in a way that future trouble could be eliminated.

 

[Hawk81]

Still pretty close IMHO.
If the main feed is 80a and they already have an electric shower and a range cooker and wants to also add another shower, cooker and lots of sockets.

Only take 2 people having a 10.5 kw shower whilst the wife is doing the Sunday dinner.

The op says power shower so that to me does not mean electric shower as in 8kw or over. It means something with a 5amp fuse. So 2 of those would not worry me.

 

[SKY]

I maybe wrong but I feel that he means electric showers, he is only mentioning high current pulling appliances in his post so i'm sure he would not mention a power shower.
but I could be wrong, maybe he will clarify.

 

[Hawk81]

You could be right. If the op would carify then we could advise further. To me a power shower is not an electric shower.

 

[Jackflash]

oh sorry, yes i do mean an electric showers about 8kw-10.5kw

 

[malcolmsanford]

As the showers even if they are used together be on for just a few minutes chances are the fuse would not blow as a 80 amp fuse as a built in rupture capacity of nearly twice the rating, on overload, depending of course on what type of fuse it is.

IMO though if your going to have an extension that large it may pay to contact the DNO to see if they could upgrade to a 100amp supply. This would depend on their cable coming into the property and of course you upgrading the tails to 25mm^ from the meter to the existing CU.

 

[Jackflash]

Yes that was my next thought, i'l make some calcs and perhaps enquire into getting the bs1361 80A uprated to 100A and making the appropriate changes to the tails etc. Thanks!

 

[multicore]

i was on a job where we fitted a contactor to control the circuit so when one shower was on the other could not come on, or could they just have one shower of the hot water , maybe pumped ?

 

[SKY]

The idea is also keeping it future proof, adding a pumped shower may mean that in a few years time new owners may install in an electric shower.
This is an ideal opportunity go the the incoming supply uprated if possible.

 

[Jackflash]

Hi again,

If i got the dno to uprate the main fuse to a 100A i think i would ge them to also install a Henley block so i could perhaps add another set of tails to install a single way 50a rcd (like a shower cunsumer unit) as the existing distribution board has an 80a main switch. I could then supply the new consumer unit with a 16mm swa. does this make any sense and sound sensible? thanks very much!