Shower - Electric Shorting Circuit Breaker

[Butt3r5]

Hi,
I recently bought a flat with a triton shower installed. The shower is causing the mains circuit breaker to trip after approximately 7-8 minutes. I could do with some help diagnosing the problem and providing a solution.

Summary:

There is a mains switch for the cooker in the kitchen which the power to the shower runs through. i.e. If the cooker switch isn't on, the shower can't be turned on.

The circuit breaker for these appliances is a 30 amp breaker which as noted trips after about 7 mins in the shower.

Thanks for your help

Butt3r5

1) Has this been wired incorrectly?
a) Should the shower be on a breaker of it's own or is it ok to power it from the same point as the cooker.

2) Whats causes the trip and why consistently after 7 minutes? Is there an increase in ampage/voltage with time?

3) What other tests can I perform to pin down the exact problem?

4) Does this need re-wiring, where should the electric shower be powered from and what is the most suitable course of action?

 

[JohnD]

1) Yes, Yes, No (it's unusual, although there are ways it could be done safely, I have the feeling that it probably isn't, because the rest of your description suggests a shoddy installation).

2) I think you will find that your shower draws more than 32Amps. an MCB does not trip immediately at 32.00001Amps; the higher the overload the faster it trips.

3) You can have a look at the shower unit, and any instructions (ha ha) to see what its power is. If you run the shower at low power (warm not hot, if it has a "Summer" setting) it will probably not trip.

4) Yes. I would recommend you stop using that shower. Look for a qualified electrician who is a member of one of the approved schemes and is permitted to test and certify his own work and issue you with an installation certificate. If he is, he will proudly say so in his advert, on his business cards on on his van. Ask around your friends and neighbours for a recommendation, then ask about qualification and which scheme he is in (there area few). Ask him to inspect and quote. You will probably need a new dedicated cable to the shower from your consumer unit, and some tidying up around the cooker control. He will include an RCD in the shower circuit, this adds a little to the cost but is an important safety feature. You can ask if there is other work he recommends needs doing, as your installation does not sound very good.

 

[Qedelec]

You failed to say what the rating of the shower is.
MCB's do not trip at 32.01Amps but will after a period of time on overload.
No one I know makes a 30Amp MCB so that needs clarifying.
If its a B32 MCB then the current being drawn is quite high and needs investigating asap.

 

[JohnD]

If it really is a 30A MCB, it's probably one of those "push button" Wylex plug-in MCBs, so is going to be fairly old, and the CU and rest of the wiring may be even older.

 

[Butt3r5]

Thanks John,
You gave me all of the answers I expected i.e. that I need to get a pro in. This could hurt the wallet. No other method of cleaning so i'll have to get it resolved asap.

Thanks for the advice.
Butt3r5

1) Yes, Yes, No (it's unusual, although there are ways it could be done safely, I have the feeling that it probably isn't, because the rest of your description suggests a shoddy installation).

2) I think you will find that your shower draws more than 32Amps. an MCB does not trip immediately at 32.00001Amps; the higher the overload the faster it trips.

3) You can have a look at the shower unit, and any instructions (ha ha) to see what its power is. If you run the shower at low power (warm not hot, if it has a "Summer" setting) it will probably not trip.

4) Yes. I would recommend you stop using that shower. Look for a qualified electrician who is a member of one of the approved schemes and is permitted to test and certify his own work and issue you with an installation certificate. If he is, he will proudly say so in his advert, on his business cards on on his van. Ask around your friends and neighbours for a recommendation, then ask about qualification and which scheme he is in (there area few). Ask him to inspect and quote. You will probably need a new dedicated cable to the shower from your consumer unit, and some tidying up around the cooker control. He will include an RCD in the shower circuit, this adds a little to the cost but is an important safety feature. You can ask if there is other work he recommends needs doing, as your installation does not sound very good.

 

[Butt3r5]

Hi all,
I've looked at the consumer unit which is carrying the MCB that continues to trip. The CU is a has a metal casing screwed on with MCBs with flip switches to turn on/off the circuit breaker.

As John noted it looks as if it is really old as one of the MCBs is a 30 amp.

What i'm wondering is if anyone knows the Crabtree website?

How difficult it is to wire up a new CU?

I have other issues that need an electrician but i'm trying to keep the cost as low as possible.

Thanks in advance
Tim

If it really is a 30A MCB, it's probably one of those "push button" Wylex plug-in MCBs, so is going to be fairly old, and the CU and rest of the wiring may be even older.

 

[JohnD]

Are the circuit breakers dark brown? It might be a Crabtree C50 installation. These are long obsolete. Though they were top class in the 1950's and 1960's. I've got a few in the loft that I was hoping to sell on Fleabay as historical curiosities.

 

[Butt3r5]

Hi John,
Couldn't tell you i'm afraid. I've not had the Consumer unit front off (has to be unscrewed and removed) as i'm failry new to electrics. I image that most modern Consumer Units have a flip front allowing easy access to the breakers.

How difficult/expensive is to the get the Consumer Unit replaced. Would a sparky charge a fortune for such work.

Getting more expensive by the day.

Are the circuit breakers dark brown? It might be a Crabtree C50 installation. These are long obsolete. Though they were top class in the 1950's and 1960's. I've got a few in the loft that I was hoping to sell on Fleabay as historical curiosities.

 

[JohnD]

Likely to be a matter of some hundreds I would have thought, a lot depends on what he discovers needs upgrading during the tests. I'm not an electrician.

Look for a qualified electrician who is a member of one of the approved schemes and is permitted to test and certify his own work and issue you with an installation certificate. If he is, he will proudly say so in his advert, on his business cards and on his van. Ask around your friends and neighbours for a recommendation, then ask about qualification and which self-certification scheme he is in (there are a few). Ask him to inspect and quote. You will probably need a new dedicated cable to the shower from your consumer unit, and some tidying up around the cooker control. He will include an RCD in the shower circuit, this adds a little to the cost but is an important safety feature. You can ask if there is other work he recommends needs doing, as your installation does not sound very good.


BTW one of my relations recently had an electric shower fitted, and a new 2-way CU to feed it (the existing CU being small, full, and old). It later struck me that it would have been nice to have had a larger, split-load CU fitted, with room for additional circuits in future work as an empty CU box costs very little more for a large empty box than for a small one.

I thought from what you said that it was a Crabtree? They are a good-quality manufacturer. You can still get parts for their Polestar and Starbreaker ranges, but you would be better advised not to take the front of the CU yourself, some older ones have exposed live parts inside even when switched off.
http://www.electrium.co.uk/download.asp#pos_crabtree

Can you lay your hands on a digital camera and put up some pics? We like them and they can often make a situation clear.

 

[SUNRAY]

I regularly come across 5, 10, 15, 30, 60 Amp MCB's Type 1, 2 and 3.

Usually in commercial environments where the stuff lasts a longer.

Stocks of these old (and maybe used) MCB's do tend to be stashed for repairs / alterations to avoid the need for CU replacement!