triton osiris shower cutting out

[buzzard2009]

hi,
wonder if you could help me with this one? ive just fitted a new shower,all went well on the test and then it cut out,i checked the mcbs and non of them has tripped.i have two consumer units,side by side.the one nearest my meter has sockets,cooker,heating ring and lights.the second one has mcbs(square d type) that has all my electric storage heaters on,hallway,bedrooms,bathroom ect.
i took the heater out of the bathroom,and wired my shower into it,as it has a switch on the landing outside the bathroom to isolate the socket,i put in a 40a mcb on the consumer unit,where the heater was.
the first consumer unit is unafected,but the second has no power,well it didnt for a couple of days,then power was mysteriously renewed,without me doing anything,im stummped as nothing has tripped out.i started the shower tonight and lost power again,nothing tripped,but lost all power to the second unit.
any help please,its a weird one?

 

[Taylortwocities]

Are you mad?

What is the power rating of the new shower?
What was the value of the old mcb that you took out before you put the 40amp one in?

My gut reaction right now is that you have melted the cable because it is not up to the power you are putting through it.
If so you can expect the fire brigade to be required to extinguish the house fire that will happen.

DO NOT USE THE SHOWER

until this is sorted out.

 

[buzzard2009]

yes i am mad thanks,
cables not melted,plenty thick enough 10mm,the mcb was 16 amp,everything else is unaffected,but think the second consumer unit is econ 7,which will explain loss of power i guess?

 

[Taylortwocities]

Yes. econ 7 is only on at night.

How did you measure that 10mm? Did you put a new cable in, or did you measure the width of the cable sheath?

 

[buzzard2009]

twin and earth core thickness,only run same thickness cable from the heater sockett to the shower unit about 4m.
i have power now,just checked.definatley the econ 7 unit,will have to move it over to the 1st consumer unit tommorow.

 

[Taylortwocities]

Don't forget the 10mm refers to the cross sectional area of the cable core.

I do hope you know what you are doing - pretty basic putting it on the off peak board.

Oh by the way

Is there an RCD protecting the shower circuit
and
Did you notify your local authority before doing this (notifiable) electrical work?

 

[buzzard2009]

yep local authority informed,i put an extra rcb on the switch outside the bathroom.
i didnt even know i was on econ 7,just thought it was a seperate consumer unit.
will sort it later,then get it checked by my brother before i use it hes a elec engineer,he should know??

 

[1john]

strange for there to be a 10mm cable on a 16A breaker feeding a bathroom heater. sounds like a bit of a hash up, unless there was a shower there previously and the old cable got utilised? All sounds a bit suspect, also are you certain that the cable is 10mm in it's entirety?

 

[bernardgreen]

i didnt even know i was on econ 7,just thought it was a seperate consumer unit.

At least he can admit he is not a "know it all" type of person.

So what could be happening. The switch on the landing may be getting very hot and going open circuit when the shower is overloading it. Then it cools and the contacts settle down and close.

Or maybe still in the circuit there is a real thermostat for the heater. If the OP didn't recognise econ 7 he could just as easily miss a thermostat in the circuit.

 

[ban-all-sheds]

i put in a 40a mcb on the consumer unit,where the heater was.

Ye gods.

Before you did that, did you confirm that the current carrying capacity of the cable (Iz as in Ib <= In <= Iz), given its type, it's installation method, and any other de-rating factors which apply to it was at least 40A?

Surely you must realise that you don't actually know anything about circuit design etc, so what on earth made you think that it was OK for you to mess with your electrics?

twin and earth core thickness.

//www.diynot.com/wiki/electrics:flatpvccables

Cable sizes are not specified by thickness.

yep local authority informed

So before you did any work to install this shower, add cables, replace MCBs etc, you applied for Building Regulations approval, which would probably have cost more than the shower itself?

To do that you would have had to tell them how you would ensure that your work would comply with the Building Regulations. So regarding Part P of those, what did you tell them?

And when they came and inspected your work, what did they say about it?

 

[mikhailfaradayski]

why dont you just have showers in the middle of the night when the econ7 is switched on?

The added benefit of this is that the firebrigade arn't usually as busy at those times and will be able to get to your house faster when it catches fire.

Ask santa for a fire extinguisher for christmas

 

[sparkwright]

could you send us some photos, particularly of the cable and the switch (and inside) outside the bathroom. we would be able to confirm what is ok and what isn't. we love pictures.

 

[Taylortwocities]

What is the point of coming on a forum, asking advice and then saying you know it all.??????????

The best of luck when you come to sell your house pal.
Most people dont like buying places where people's family have died due to the stupidity of the owner.

 

[TheOriginalTonkaToy]

Well if you had it all checked by an engineer, why didn't he tell you where to connect it, how to test it, or better still install it himself. Engineers don't necessarily know the requirements of domestic installations.

People asked you to confirm the CSA (cross sectional area) of the cable and you haven't. You've said it was installed on a 16A MCB which is vastly underrated for the type of circuit. Several other things you've said make it clear that you're out of your depth on this.

The problem is that electric showers of this type are high current devices. One mistake can lead to overheating somewhere in the circuit and can cause fire. That's before we even get onto the topic of mixing water and electricity and the implications on human life that a bad install can have. What people are trying to do, albeit somewhat harshly on occasion, is to try to bring home to you how much of a risk this install is and how important it is to have it correctly designed and installed for your sake and the sake of your family.

 

[TheOriginalTonkaToy]

You've been given excellent advice and guidance. If you think you know better then go ahead and accept the risk. If you have a family then consider them first.

Yes, there are cowboys in cyberland as you put it, so be careful not to breach any insulation with your spurs