Shower keeps tripping the fusebox

[ban-all-sheds]

IHNI - why do you ask?

 

[ban-all-sheds]

40A RCD

Is this the only trip switch on that circuit?

Batesy, this is important - are you sure it's an RCD that's tripping, not an MCB or an RCBO?

Does it have a test button?

Does it say B40 anywhere on it?

Photos might be handy...

 

[batesy2000]

The top pic is the consumer unit and the bottom is a close up of the one that trips - number 4

 

[ban-all-sheds]

OK - that's an MCB, not an RCD, so it will be tripping on overload.

An 8.5kW shower will not overload a 40A breaker, so there must be a fault somewhere - possibly the cable near the isolator. As the RCD isn't tripping it's a L-N fault. If it's overheating, and has a bend near the connections then the conductors could slowly migrate through the insulation and touch. I'd expect that to leave a pretty permanent fault situation though.

Hopefully others here can help via having seen that sort of problem before?

 

[flameport]

The shower would run for around 7 minutes then trip. The fusebox was humming too.

I would be very suspicious of the circuit breaker, considering:
a. how old it is
b. who made it
c. how it fits into the consumer unit.

 

[flameport]

Got electrician in who checked fusebox,

Was that just a visual examination?
Did they remove the circuit breaker from the box to inspect the connecting terminals?

 

[batesy2000]

The circuit breaker wasn't removed but he did test the connections with some fancy looking meter reader thing. I know it wasn't a simple multi meter.

The humming stopped once a new iso was installed. Now its tripping again, the box is humming again.

 

[batesy2000]

The circuit breaker and consumer unit are indeed old but why would everything be "okay" for two weeks with a new iso and now it's as bad as it was.
There's a circular "junction" box in the loft I noticed, no idea what runs to or from it. Could that be the issue,? Or am i grasping at straws here. Who'd have thought a shower would be such a pain. It worked fine for 8 years......

 

[JohnD]

Not odd at all if, as you say, it had been getting hot.

As a competent electrician knows, heat damages the copper cable, so just swapping the switch often is followed by a recurrence.

I believe you said the "earth wires" have been left unsleeved. This is not a sign of a competent electrician.

 

[JohnW2]

OK - that's an MCB, not an RCD, so it will be tripping on overload.

Eh? I'm confused. Since when would an MCB be labelled "Earth Leakage Circuit Breaker" and "IΔn=0.03A", and have a test button?
However, as said, it looks well past its sell-by date (even if it was OK in the first place!).

 

[EFLImpudence]

The MCB to the left - circuit number 4.

 

[JohnW2]

The MCB to the left - circuit number 4.

Ah I didn't see that note below the photos - and since the photo 'majored' on the RCD, I thought it was being implied that that was what was tripping.

Kind Regards, John

 

[batesy2000]

You think I should get a whole new consumer unit?
Looking at other people's mine does look archaic.
Would that be a costly job?

 

[flameport]

You think I should get a whole new consumer unit?

Definitely.
That pile of junk is a Federal Stab-Lok. A notorious and entirely useless design from the start.

Although the majority of dangerous failures on such things were in the USA, the UK ones were pretty much the same design. Fortunately they were not popular here, so very few were installed and even fewer still exist.

Would that be a costly job?

Depends on what you consider costly, although it's much cheaper than having the existing one burst into flames, electrocute people or similar.

The humming stopped once a new iso was installed. Now its tripping again, the box is humming again.

Isolator is unrelated, the noise may have stopped just because the circuit breaker was moved slightly when it was inspected previously.
In any case, circuit breakers should not make humming noises or any other noises in normal use.

 

[winston1]

You think I should get a whole new consumer unit?
Looking at other people's mine does look archaic.
Would that be a costly job?

No as I said earlier replacing things that you don't know are faulty is a waste of money and time.
You acknowledged that you felt an idiot for doing just that.

So find out where the fault is.