Massive damage. Neutral fault

[snowhead]

Just trying to understand why they would've wanted to switch the neutral in this way?

The person installing the 4 pole probably didn't think it through and probably hasn't seen the results of doing it,, untill now.

 

[havo one]

I work for an FM company, we’ve just taken on a brand new refitted and rewired premises.

There is a 3phase DB supplying sockets into which there were loads of electronic equipment which has suffered multiple failures. The DB is supplied via 4pole contactor which is switching the Neutral. It’s a TNCS supply and I’m thinking this contactor switched Neutral is the problem. The contactor has now been replace with a 3 pole and solid link to Neutral.

Thoughts??

I’m thinking just the action of switching the contactor may have meant that not all 4 poles closed at the exact spilt second and might have cause massive overvoltage in the phases. Or the neutral was open circuit for a time leading to anywhere up to 415v applied in the phases.

I wouldn’t say I’m an expert on this but this is my understanding of it.

hope it's ok to sidetrack a little, we are fitting 4pole contactors on boards at present so staff can have an easy mode of switching off at end of shift. There are lots of gaming machines connected to the circuits most of which have inbuilt computers (I believe) do you think I should connect neutral direct. Thanks

 

[snowhead]

do you think I should connect neutral direct.

Yes without a doubt.
Who decided on the 4 poles?

 

[Nigel]

Thoughts on what?

 

[havo one]

Yes without a doubt.
Who decided on the 4 poles?

tbh i ordered the contactors myself without considering the implications of the neutral switching. ill connect neutrals direct tomorrow.
thanks.

 

[Farmelectrics]

Change the neutral to a solid link and see if that solves the issues