Using 2 100mA RCD's for essential and non-essential circuits and nuisense tripping

[Lighthouse Phil]

Hi All. I'm working on a project in Northern Ireland. The supply is protected by a 100mA RCD which is regularly triping due to many items of our plant have high earth leakages. We have a large IT area, which, as many of you will be aware of, has a high earth leakage. We also have a good few battery chargers (again, the transformers are an area of earth leakage), and the usual domestic side of things, lights, sockets etc.
My thinking was to split the loads into two areas, that is, to have the battery chargers, IT equipment and our other essential loads on one 100mA RDC. The essential loads are backed up by a auto-start Genarator. The other non-essential loads to be supplied by a second 100mA RCD, but not with generator back up. All the circuits will be re-terminated into new consumer units and protected by RCBO's.
My Question to you guys is this :: Even though all the circuits will be protected by its own RCBO, the over all Earth Leakage Current, on my essential circuits will (sometimes) be over the 100mA threshold. All our IT equipment is state of the art, costing many thousands, each battery charger costing many 100's. It's not an option of replacing this equipment.. How do you guys working in similar industial situations, cope with nuisence tripping?

 

[Deleted member 9648]

Re: Using 2 100mA RCD's for essential and non-essential circuits and nuisense trippin

Is the system TT?...If so could it be converted to a TN system...you could then do away with the RCD's on most of the essential equipment.Probably the only thing which would require protection would be sockets intended for general use.....if it's already a TN the same would apply.

 

[Sintra]

If you are putting each circuit on it's own rcbo then you can do away with the 100mA RCD's completely providing your supply tails are going into a plastic unit.


Sent from my iPhone using Tapatalk.

 

[Lighthouse Phil]

Re: Using 2 100mA RCD's for essential and non-essential circuits and nuisense trippin

Thanks for the quick replys lads. It is a TT system, but Sintra has answered the question very simply and beautifully.........Thanks to both of you.

 

[Doomed]

Re: Using 2 100mA RCD's for essential and non-essential circuits and nuisense trippin

One option would be to have the high earth leakage items on a non RCD protected surface mounted circuit (in conduit), you are not in a domestic environment and as long as the sockets are labeled to state that they are not RCD protected and are only for the use of the IT equipment only and for the use of trained personnel you are OK (I think).

Splitting the circuit into multiple circuits with thier own RCBO.

I have heard of fitting isolating transformer and bonding the 'neutral' side of the secondary to earth, but one of the better brains here would have to look into this one as I have never done it.

 

[Deleted member 26818]

Re: Using 2 100mA RCD's for essential and non-essential circuits and nuisense trippin

One option would be to have the high earth leakage items on a non RCD protected surface mounted circuit (in conduit), you are not in a domestic environment and as long as the sockets are labeled to state that they are not RCD protected and are only for the use of the IT equipment only and for the use of trained personnel you are OK (I think).

Splitting the circuit into multiple circuits with thier own RCBO.

I have heard of fitting isolating transformer and bonding the 'neutral' side of the secondary to earth, but one of the better brains here would have to look into this one as I have never done it.

It's TT, and unless the resistance to earth is very very low, RCD protection is a must.

 

[Doomed]

Re: Using 2 100mA RCD's for essential and non-essential circuits and nuisense trippin

Phil stated it was TT while I was typing my reply - Your correct spinlondon, ignore option one!

 

[Deleted member 9648]

Re: Using 2 100mA RCD's for essential and non-essential circuits and nuisense trippin

If you are putting each circuit on it's own rcbo then you can do away with the 100mA RCD's completely providing your supply tails are going into a plastic unit.


Sent from my iPhone using Tapatalk.

The problem with this is that essential circuits will still be on an RCD and despite a lot of work nuisance and costly tripping (of individual circuits) may still occour......I still think converting to a TN system would be a far better option.