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]

Me too, this wipe the whole lot out, rcds & mcbs, bridge you bus bars on a install and see for yourself.

Tony, due you think moist air that another member mentioned could contribute to this?

 

[vernam616]

Rcd detects a imbalance in the circuit

 

[pmac10]

Rcd detects a imbalance in the circuit

caused by excess current to earth.

 

[p11jor]

There was no continuity between neutral & earth and untill the shower is switched on from the body of the shower not the iso switch then we are all good and no tripping. But when the shower was activated both rcds and all 4 mcbs blew.

 

[Engineer54]

Tony, due you think moist air that another member mentioned could contribute to this?

Sure it can, but it would have to be pretty dammed moist/humid air to get 230/240 volts to jump 6mm!!!

 

[Big n Daft]

Maybe not!
Cross a nuetral and it becomes unbalanced across the RCD.

Bugger...............to bloody quick to reply you lot

 

[vernam616]

A residual-current device (RCD) is an electrical wiring device that disconnects a circuit whenever it detects that the electric current is not balanced between the energized conductor and the return neutral conductor.

In a pme system the neutral will be at the same potential

 

[p11jor]

Obviously it's not jumping that If no one is taking a shower, but as soon as the button is press it will drawn power from that board....(same as sometimes you see a flash in a light switch when pressed) how far can that jump at the very moment the shower draws power?

 

[p11jor]

Big n daft
The neutrals were in tge correct bars!

 

[vernam616]

What make board is it?

 

[Engineer54]

Obviously it's not jumping that If no one is taking a shower, but as soon as the button is press it will drawn power from that board....(same as sometimes you see a flash in a light switch when pressed) how far can that jump at the very moment the shower draws power?

That is an arc that's being drawn across two contacts, normally when being switched Off. Not the same thing as two static bars and an arc jumping across them....

 

[ian.settle1]

Big n daft
The neutrals were in tge correct bars!

Am I being daft but what is tge?

 

[vernam616]

Wheres that tongue in cheek smiley

 

[p11jor]

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.

 

[vernam616]

I dont understand why people buy these d/bs, i can get a dual split wylex with breakers for £70, im pretty sure other people can too