Guess the fault

[p11jor]

Had a call out late last night, everytime the shower comes in it's blows the whole house.

The set up of the board is duel rcd. 2 mcb either side.

Cooker/shower on left

Lights/sockets on right



So the power to the shower switch is fine, again this can function fine and send power to the shower, bit as soon as the shower is pressed is wipes both rcds straight out after 2seconds.

I did a insulation resistance test, was getting 0.25megohms.
Removed tge switch and was getting 459megohms. So thought new switch, put new switch on and still wiping the whole board out, but obviously were not getting a dead short as the power to the shower is fine untill pressed.

Quite interesting this one. But such a obvious one which I will always look out for on my future PIRs

 

[p11jor]

Ian it's my phone, it's ment to be "the" but the "h" & "g" are so close on
The touch screen and it dosnt auto correct for a few seconds by that time i have pressed post!

 

[topquark]

caused by excess current to earth.

Not necessarily, if there's a route back via another circuits neutral (under fault conditions) the rcd will trip if the imbalance L->N is in excess of the rating (nominal 30mA).

 

[p11jor]

To be fair I had bought one for £60 a protek one and that seemed ok, are they anygood?

Also just installed a Chint one which was apparently "ip" rated so could take top entry without sealing "according to wholesaler"

But your right screwfix (elecfix) have mk ones on offer at mo £50 + vat and that's with the breakers.

 

[Engineer54]

But that's what I stated in my first post that it's not a static problem!

Vernam616 it's a CED mate, one of them £50 specials.

Static in this case, meaning ''stationary or fixed'' not a static electrical charge!! ...lol!!

 

[p11jor]

Topquark is totally right there.

 

[topquark]

Not necessarily, if there's a route back via another circuits neutral (under fault conditions) the rcd will trip if the imbalance L->N is in excess of the rating (nominal 30mA).

Someone was also postulating about the posibility of an induced current from one RCBO to an adjacent RCBO causing a trip (must be very poorly designed if that's the case though).

 

[vernam616]

Local well known wholesalers sell wylex/mem/mk cheap enough, i find these cheap ones are horrible to work with too, fall apart/clips snap/cant get lid back on correctly etc...

 

[pmac10]

can you check the insulation of the heating elements in the shower unit?

 

[topquark]

Topquark is totally right there.

YeeHaa! Got one right for a change

 

[p11jor]

Lol, but soon as that shower draws it's power then surely this would be able to cause say a 2nm jump to the next bus bar? Or would it! I don't kno, I bin at it for only 7 years, but my mate i work with has been at it 49 years and he gas never saw this, he couldn't even explain why.

 

[vernam616]

I agree topquark, makes me wonder how some people became electricians or more worryingly let loose in domestic dwellings with some comments ive seen on the forum as of late

 

[p11jor]

Pmac10 what voltage would you do a IR at for this?

 

[vernam616]

With it being dark they may have been a small raggy stray bit of copper which you overlooked ( been late and dark etc... ), busbars were close enough for a little peice to touch the other, you snipped the bar back and its solved the problem

 

[topquark]

Lol, but soon as that shower draws it's power then surely this would be able to cause say a 2nm jump to the next bus bar? Or would it! I don't kno, I bin at it for only 7 years, but my mate i work with has been at it 49 years and he gas never saw this, he couldn't even explain why.

It would only jump if there's a PD to make it.

 

[topquark]

I agree topquark, makes me wonder how some people became electricians or more worryingly let loose in domestic dwellings with some comments ive seen on the forum as of late

Okay, Okay, I'll stop commenting now