Street lighting causing RCD to trip?

[Ponty Massive]

Evening all,

Had a call today from a customer I did a job for a few months back. I went in to install a socket for them, only to find that the circuit had been put on the non-rcd side of the board (16th board). Asked the woman if she had a copy of the certificate when she had the board changed, which she did.

The guy who installed is a part P spark. She had the board changed because she had a new bathroom with jucuzzi. After having the board changed, the RCD would trip now and again for no reason. The original spark came back and just moved the mcb (which was also powering the jacuzzi) to the non-rcd side and like magic the problem went!!

I fitted the socket and moved the mcb back to the protected side and asked them to keep an eye on it, and let me know if it goes again.

Had a call today saying it has tripped about 3 times in the last 2 weeks, but they seem to think it is happening when the street lights come on. They assured me they were just sat in the room watching TV and when the street lights came on it tripped?

Has anyone else come across this problem before?

 

[Chr!s]

Upstream tranisants/noise can trip down stream rcds, difficult to say if this is your problem.

Dno may monitor supply if this is what you think may be the case.

 

[Ponty Massive]

Thanks Chris, did think of that, but why would it stop tripping when the other spark moved the MCB. I think it must be that specific circuit, but they assured me nothing had been operating, only the street light switched on??

 

[Ponty Massive]

Anyone else got any idea's guys?

 

[SimpleSimon]

It could be a needle in a haystack situation mate. Possibly something they are plugging in at that time? 3 times is really intermittent.

 

[Marvo]

I've heard of ballasted street lights causing nuisance tripping but I haven't heard of a solution. I'm not sure if it would be a harmonics issue with the lighting switchgear. I know some RCD's are more prone to this type of nuisance tripping than others.

I've attached a pdf that might give you some ideas.

View attachment DemystifyingRCDs.pdf

 

[BillySparks]

yeah seems strange, could try changing the rcd if its possible for a different make.

 

[Ponty Massive]

Thanks all, Yeah I'll start by changing the RCD and see where we go from there. With it being so intermittant, it could take some time.

Cheers all !!

 

[nickblake]

I know this may sound daft but have you checked the connections where the bus bar fits into the MCB's , ive come across this situation and found that the grip terminal for the mcb had missed the bus bar and was resting against it it tripped the RCD about 20 mins after the heating came on , i know its a daft one but may be worth checking also is the Ze ok i have had this caused by the neutral going down on the supply which caused the RCD to trip

 

[Ponty Massive]

They are on holiday at the moment, should be back next week. I'll have a look and try all your suggestions, Nickblake it's normally the daft idea's that turn out trumps !! Ta all.

 

[Paul.M]

My also be worth while seeing if they have a security light with a photo cel if it trips at the same time as the street lights kick in on their own photo cel. Just a thought.

 

[Ponty Massive]

My also be worth while seeing if they have a security light with a photo cel if it trips at the same time as the street lights kick in on their own photo cel. Just a thought.

Good idea.....Think I'll start making a list.

 

[tony mc]

I would have a go a putting a RCBO in for that circuit on the unprotected side to stop any major inconveniance to the customer in the short term.

It could be that the main RCD is at its limits with the leakage on that bussbar on something going on is enough to trip it adding up the leakage.

Might be worth ramping the RCD and sticking a clamp meter on to see what the mA drain is.

Mind you agree with all the above ideas and like nickblake says its normally a daft idea that gets it fix.

Photo cell is a good sugesstion as well Paul.

Good luck.

 

[ian.settle1]

I would have a go a putting a RCBO in for that circuit on the unprotected side to stop any major inconveniance to the customer in the short term.

It could be that the main RCD is at its limits with the leakage on that bussbar on something going on is enough to trip it adding up the leakage.

Might be worth ramping the RCD and sticking a clamp meter on to see what the mA drain is.

Mind you agree with all the above ideas and like nickblake says its normally a daft idea that gets it fix.

Photo cell is a good sugesstion as well Paul.

Good luck.

My thoughts as well, it may not be one item off equipment but a number of items which are not always on together but when they are they cause the the RCD to trip.