Two Electric Showers In One House!
Andy H
I am struggling to decide if it is acceptable to fit an additional shower:
My domestic supply is fused at 100A
My existing consumer unit has a 100A Isolator
The original 9.5 kW shower is supplied via the 63A RCD (along with the two
32A ring main circuits).
Other loads are standard (2x6A lights, 32A cooker, 16A Emers. htr).
Is it possible to fit another shower?
I'm thinking along these lines: -
Replace existing shower with 7.5kW version ( to reduce load)
Replace existing 63A RCD with 80A RCD (never been happy with two rings and
shower off the original 63A RCD)
Reduce rating of cooker circuit to 20A (oven only, no hob, no socket fitted)
Possibly disconnect the emersion heater (to reduce max demand, if I have to)
Install splitter to meter tails and fit additional consumer unit with own
isol, RCD
Install second 7.5kW shower fed from new consumer unit.
Hmmm, still looks a bit close!
I can't be the first person to want two electric showers - what does
everyone else do?
Is 100A the largest domestic supply I can get?
Any help greatly apreciated.
Andy H
REMOVE THIS@hotmail.com RMS
news:ai3ekg$ajb$1...@newsg4.svr.pol.co.uk...
We have two - an 8kW & 8.5kW, plus two of most electrical appliances (granny
flat) on an 80A main fuse!
It has gone once - middle of winter when we were cooking Sunday dinner so
that was (as far as we know):
Oven
2 rings on cooker
microwave
2 showers
at least 1 3kW fan heater
3 1kW space heaters
lights, stereo, tv, 2 computers
and I think it was the immersion which was the final straw!
All in all, probably well over 100A and that was on a 63A main fuse! The
electricity board guy (YEB) was here within 1 hour (they class it as an
emergency) and replaced it with an 80A.
Fuses are rated to blow at (I think) 2 or 3 times their rated current, or
for prolonged periods near their rated current, so I would say as long as
you are sensible and try to remember not to have all your high consumption
devices on at once!
Robin.
Chris Oates
"Andy H" <an...@ahackett.freeserve.co.uk> wrote in message
news:ai3ekg$ajb$1...@newsg4.svr.pol.co.uk...
>
> I am struggling to decide if it is acceptable to fit an additional shower:
>
> My domestic supply is fused at 100A
> My existing consumer unit has a 100A Isolator
> Replace existing shower with 7.5kW version ( to reduce load)
> Replace existing 63A RCD with 80A RCD (never been happy with two rings and
> shower off the original 63A RCD)
Who did this ??
you really have 2 rings and a shower running from a 63A RCD !!!!!
where are the MCBs/Fuses protecting each individual circuit ?
100A consumer unit can only have ONE high load and it must be
the first from the switch - should be the Oven
Showers should (ideally) be on separate one way CU with MCB and RCD
tailed back to the Electric board blocks
Cable sizing is very important as large voltage drops can occur
as well as unwanted heating effects
I've got 2 CU and dedicated RCD/MCB shower feeds - this stuff
is very cheap now and having more boxes makes wiring it up much
easier
Andy H
Maybe I didn't explain it very well.
The original CU is of the "standard" split design, consisting of:
Left to right
100A incoming DP isol
32A MCB (cooker)
16 MCB (Imm. Htr)
6A (Lights 1)
6A (Lights 2)
two spaces
63A RCD feeding RHS of board which consists of
32A MCB (ring 1)
32A MCB (ring 2)
40A MCB (shower)
The consumer unit, although only 12years old, is no longer manufactured, so
I need to replace it anyway.
I intended to purchase a typical 100A split 5+5 CU but this time with an 80A
RCD as the 63A original is clearly overloaded.
Wiring would be pretty well as above but the shower would be replaced with a
lower wattage version and protected by a 32 MCB (not 40A).
To fit the second shower I was going to fit a dedicated (small) CU with it's
own RCD and MCB, this was to be supplied by splitting the meter tails
adjacent to the original CU, using a purpose built 100A splitter. Each CU is
then fed from the splitter using DI tails.
I note that the commercially available "shower extension" CU's don't seem to
have an an incoming isolator - just an RCD. Is it OK to connect this
straight to the meter tails or would it be advisable to fit a 100A isol.
All cables are correctly sized for the circuit they supply and the device
they are protected by.
Existing meter tails apear to be 25mm2, maybe 35mm2.
It does not appear to be possible to run two sets of tails from the
elecrticity company equipment, so splitting is the only option.
I suppose the issue is still the total load - can two electric showers be
connected in the same house?
Andy H
"Chris Oates" <chriso...@hotmail.com> wrote in message
news:ai4mk3$eqf$1...@paris.btinternet.com...
Andy H
Thanks for replying to my post.
I'm now far more concerned about your installation than I am about mine, do
you live far from the fire station?
Like you, I'm sure I could manage my appliances to keep the load down but
unfortunately the regs don't allow for that.
I could design my system so that I didn't overload any of my equipment (by
using two consumer units), but the fact is that with two showers on (which
they would be, or why have two) it would be very easy to overload the
meter/radio switch/meter tails.
Just to make matters worse my electricity supply is generally around
249 -251V!! (thanks a bunch NPower).
I am rapidly coming to the conclusion that the second shower will have to be
a power shower.
There must be loads of properties with two electric showers - I'm still
curious as to how they solved the problem.
Best regards,
Andy
"RMS" <surfer_unlimited@PLEASE REMOVE TH...@hotmail.com> wrote in message
news:Fpb19.1779$S03.230123@stones...
Chris Oates
Ah OK understand now
> To fit the second shower I was going to fit a dedicated (small) CU with
it's
> own RCD and MCB, this was to be supplied by splitting the meter tails
> adjacent to the original CU, using a purpose built 100A splitter. Each CU
is
> then fed from the splitter using DI tails.
> I note that the commercially available "shower extension" CU's don't seem
to
> have an an incoming isolator - just an RCD. Is it OK to connect this
> straight to the meter tails or would it be advisable to fit a 100A isol.
it is common for the RCD to be used as a switch
> All cables are correctly sized for the circuit they supply and the device
> they are protected by.
>
> Existing meter tails apear to be 25mm2, maybe 35mm2.
> It does not appear to be possible to run two sets of tails from the
> elecrticity company equipment, so splitting is the only option.
>
> I suppose the issue is still the total load - can two electric showers be
> connected in the same house?
I haven't checked the Regs recently but I don't think it's prohibited ;)
same as having 3kw heaters in every room - what is the likelyhood of them
all being on at the same time (diversity is the key word)
a well designed system (you seem to be going the right way) will
pop an MCB and at worst take out the Power Co fuse try calling them
..see if they will fit a larger one
Chris Oates
> There must be loads of properties with two electric showers - I'm still
> curious as to how they solved the problem.
Nobody solves the problem, they just forge ahead regardless
Apart from high loads being on the first MCB from the switch
in a CU (or separately fed from tail blocks) you merely rely
on 'diversity' or the possiblity of maximum loading actually
occuring
In a perfect world Ampacity would be increased to cope with
theoretical load
Where I work it's like that - we feed from 95mm 3 phase and
request fusing appropriate for our load as it is constant
In a domestic situation you get 80-100A and have to make do
with it - usually works fine