both electric showers trip the rcd/isolator

[sifly1]

Hi, a friend has the above problem where either of his showers will trip the cu's only rcd/isolator. The mcb's for each shower don't trip

If I disconnect one of the heater elements from either shower both showers will heat the water.

If I switch the elements round both showers still work.

So the combined load of both heaters in either shower cause a trip.

If I disconnect both shower earth cables at the pull switches both showers still cause the trip on high setting.

All visible cables look OK and are tight.

I can't test insulation as I don't have the test equip so have told friend to get a elec in.

Just wondered do you think it could be a faulty main switch/rcd? Or is it more likely to be an earth fault somewhere?

Not now looking to fix this ....just interested.

Cheers,
Si.

 

[wingcoax]

Both showers on the same circuit? What cable/mcb is there? Sounds like the supply is not up to it.

DO NOT REMOVE THE EARTHS!!

 

[sifly1]

Hi, showers have been there 7+ years as they are. From memory the cu has 8 mcb's with a combined 100a isolator/rcd.
The shower mcb's I think were 40 & 32 OK for the shower output.

They have been away for a month, now back they have the problem, which was fine before.

They have this month off each year, no problem before.

Only thing different came to light as I was leaving, was the hot water immersion had been left on since they came back. I switched it off but the showers still tripped rcd. I didn't check it for faults.

Shed any light?

Si.

 

[sifly1]

Earth only removed after checking shower would run OK on either heater element, and meter testing. Only then 4 one second it took to trip main rcd with power on, and then replaced.

Si.

 

[RF Lighting]

Do not remove earths ever. Not even for testing. Never whilst a circuit is energised. You really have no idea what you're doing or how much danger you're creating. It doesn't matter if it was just for a second. It takes milliseconds for electricity to injure and kill.

You need to employ someone who knows what they are doing and who understands safe working practices to diagnose the fault(s) for you.

 

[mikeyd]

It could be a neutral/earth short somewhere. This could be on any circuit served by the RCD, not just the shower circuit.

If it is then it would trip when you use a shower only because this sort of fault only show themselves when the RCD is heavily loaded.

Without proper test equipment, identifying which circuit the fault is on (let alone where on the circuit) requires a lot of patience and a good understanding of what you are looking for.

So (as said above) I think you need to call in an electrician.

 

[sifly1]

Like I said sparky booked in ....i am aware of the danger, no one was near the shower, it was switched on via pull cord which was earthed. As the shower will not trip with either of the heating elements energized, I rightly or wrongly didn't think it was causing the fault, and thought this would prove it?....or at least show another fault existed elsewhere. The shower is very basic from memory, just a pressure/flow switch, 2 micro switches which energize the 2 elements in the can. (May have been basic over heat cutout....can't remember), no coil, PCB etc, all control by two mechanical rotary valves. The disconnected earth was put in a spare block and all removing of cables were done with all mains off at cu isolator.

I didn't mean to distress u, and if u can tell me where I nearly killed myself I would be greatful as I try to remove risk before i do any type job.

 

[sifly1]

Mikeyd, thanks 4 your reply, I think u may be right, I will let u know after the sparky sorts it. I was asked if they needed new showers, hense trying to prove they were OK with just a multi. Won't remove earth again 4 testing

Thanks again
Si.

 

[ban-all-sheds]

... 4 ... u ... u ... 4 ...

Si - please use proper English when posting here.

 

[sifly1]

Proper English?? Anyway quick update. Mates problem got worse last night and kettle and cooker started tripping main rcd.
His sparky cancelled so he was not happy.

He asked if I would have another look as I was there doing other work.

Thanks to the help on here I soon tracked down which circuit had the earth fault.
It was a smallish lighting circuit and it turned out to be a walllight bracket clamped across a cable had cut into all three cables, making the bridge to earth.

I will try and post a pic

Cheers
Si.

 

[ban-all-sheds]

Proper English??

Yes.

Not

"Mikeyd, thanks 4 your reply, I think u may be right, I will let u know after the sparky sorts it. I was asked if they needed new showers, hense trying to prove they were OK with just a multi. Won't remove earth again 4 testing"

but

"Mikeyd, thanks for your reply, I think you may be right, I will let you know after the sparky sorts it. I was asked if they needed new showers, hence trying to prove they were OK with just a multi. Won't remove earth again for testing"

 

[sifly1]

Joking mate

Anyway here's the pics :-

Si.

 

[ban-all-sheds]

<pictures of work done by a dangerous, lawbreaking, incompetent t**t who should have all his screwdrivers confiscated>

 

[ban-all-sheds]

<pictures of work done by a dangerous, lawbreaking, incompetent t**t who should have all his screwdrivers confiscated>

 

[ban-all-sheds]

<pictures of work done by a dangerous, lawbreaking, incompetent t**t who should have all his screwdrivers confiscated>