3rd Electric shower

[Timbo_1975]

Hi all.

Been called to look at a job after a bathroom refit and 10.8kw shower has been installed. CU is a 16th Ed. Wylex. RCD one side and isolator the other.

Already there are two 9kw showers on the RCD side + a shed feed with a 40A mcb. These two showers are likely to be in use simultaneously as the one is in a granny flat and the other a small rented annex.

Proposal is a 40a rcbo on the non-rcd side of the board for the landlords new shower having consolidated some of the (5) lighting circuits.

I am alittle concerned about peak loading. Comments?

 

[londonlec]

I think your customer needs to be advised on alternative methods of showering.
Unless they have a 3p 100amp head.

 

[johnboy6083]

if i were you, i would mention the issue to the landlord, and propose a new supply. If he refusd , as i expect that he probably will, then i would install an 80A fuse/MCB (perferably MCB) after the DNO cutout, but before the CU's. this way, if the system is overloaded, at least its not a DNO callout, but just a MCB or fuse to reset or replace. in all likelyhood, do people tend to have showers ect at the same times? And do the showers actually use all of the power, all of the time? i doubt it.

 

[Timbo_1975]

Alas a separate small CU for the new shower is not an option given that the cutout / meter etc is in a wall box about 8m from the CU which is in the top of a kitchen cupboard!!

Strangely there is a 10mm CPC installed under the kitchen sink but not a jot of cross bonding anywhere else, which the customer has also been advised will require attending to.

 

[truckster]

DNO's often require notification of two electric showers so I guess they will want to know about 3.

 

[Richard]

The chances are that you'll only have an 80A fuse (I don't think you mentioned this anyway) in the cut out. Each shower is propbily pulling near enough 40A, so with two on at the same time, not to mention any other loads, you'll be at your maximum demand. Simple answer is no. Do they have combi or is there a cylinder they can put a shower pump on?

 

[Timbo_1975]

Thanks all for the responses thus far!

There is a cylinder, and indeed a bath from it in the new bathroom, however shower is fitted, cables in place (thanks to plumber) and the room is tiled!

 

[Robinson]

Had same problem at mo but with two showers.....Had to contact DNO. They on 60amp, but gonna cost mega $$$ for 100amp so convinced them to go 80 and lose a shower. If the carrier and incoming supply cable can take 100amps its not to exspensive and if they are N power they do for free. What is the head size anyway?

 

[Timbo_1975]

Re: 3rd Electric shower -follow up-

Well the customer now has his 3rd electric shower.

Upon further questioning it became apparent that one of the original showers was an instant jobbie but subsequently had been converted into a power shower-cylinder fed. Still had a 40A MCB and JB on the end of the 10mm though! Fixed that, connected the new instant shower via an rcbo, added some bonding to cylinder etc and job was a good'un.

The customer then demonstrated to me his dimmer controlled kitchen spots AND the PIR switched outside lights which dim on command from same, so another trip back there.....

 

[p11jor]

Saw one with two 10.8 showers and two kitchens two 32amp supplies for cooker......the board was buzzing like crazy. It was a 7 bed house for students.

Think your landlord should be thinking of thermostatic showers straight from the boiler

 

[lj.l]

priority shower unit ,basicly a contactor with 2 normally open and two normally closed contacts,when shower 1 is in use shower 2 cannot be used only drawback is if your in shower 2 and someone jumps into the priority shower your left soapy.I have set up a two contactor system switched by 2 6a pull cords but am to drunk to remember

 

[BlueToBits]

I would have thought that, electrical issues aside, the water supply pressure would likely struggle to cope with three 10K showers.