Shower keeps tripping the fusebox

[batesy2000]

A few weeks ago our shower was tripping out the fusebox. The shower would run for around 7 minutes then trip. The fusebox was humming too.

Replaced the shower, still tripped.
Got electrician in who checked fusebox, shower, wiring and shower cord switch.

He said it was the shower cord switch, it was getting hot, scorch mark on N terminal and so replaced it.

Two weeks and now it's tripping again.
Very frustrating.
I had a quick look in the shower cord switch, saw nothing obvious but didn't dare mess. Noticed no sheathing on the Earth terminals.

Can anyone please shine some light on what may be up.

The shower is a Gainsborough 8.5W, electrician said cabling was correct size.

 

[winston1]

What is actually tripping, RCD, MCB, or RCBO? What size is the trip device in amps?

NB. Replacing things without knowing if they are faulty is a waste of money and time.

 

[JohnD]

electrician

What do you know about the qualifications and experience of this person?

How did you select them?

 

[batesy2000]

40A RCD. The consumer unit itself is very old but electrian checked it out with multimeter and said it was ok.

One thing i remember him doing was shower cord was off but he was still getting a current reading, it was very low but that's how he initially concluded the issue was the shower cord switch. Current leakage?

Yeah i felt a right idiot replacing the shower before getting anything checked.

 

[batesy2000]

What do you know about the qualifications and experience of this person?

How did you select them?

He's a qualified electrician does work for a family friend who is a registered boiler / central heating fitter who fit my central heating.

 

[JohnD]

Do you mean he is a member of a Competent Person Scheme? Which one? What level is he?

Some photos of the shower switch, cabling, consumer unit, MCB and RCD would help.

 

[batesy2000]

I'm at work at the moment so I'll post pictures tonight.

 

[ban-all-sheds]

One thing i remember him doing was shower cord was off but he was still getting a current reading, it was very low but that's how he initially concluded the issue was the shower cord switch.

¿Que?

 

[securespark]

40A RCD.

Is this the only trip switch on that circuit?

 

[securespark]

¿Que?

Perhaps he means the spark was checking the supply at the shower with the iso off, but he was getting something through so he concluded the iso was faulty.

 

[batesy2000]

Perhaps he means the spark was checking the supply at the shower with the iso off, but he was getting something through so he concluded the iso was faulty.

Thanks for clarifying. That sounds like what he was doing. I'm a total idiot with electrics.

 

[batesy2000]

Thing is, the iso was replaced and it was good for two weeks. Very odd.

 

[JohnD]

Thing is, the iso was replaced and it was good for two weeks. Very odd.

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.

 

[batesy2000]

What would be generating the heat? Do you think the cable has been compromised?

 

[batesy2000]

Also what does it mean when wires cross over?