Any ideas, on this one..

[nathz29]

Evening,

Visited a site today for an external lighting fault, bollards to be specific.

The circuit contains six bollards and a contactor brought in via a photocell.
Bollards sited around a mill conversion 4 to the front and 2 to the rear.

Protected by a 6A mem rcbo

They rcbo trips whenever the contactor de energises if all the bollards are in cct, if isolate the two to the rear the trip does not occur.
No signs of water ingress.on most bollards, ir testing on the accessible cabling to the rear appears ok, ir tested n-e ok,
The two bollards to the rear show signs of water ingress, had those in bits and checked the connections replaced corroded lamp holders and terminals (bollards are just contain lampholders via fused terminals, no gear in there thankfully)
As soon as any load is added to the rear bollards, it trips.
I can't access all of the cable run to the rear bollards as it's within the mill walls and looks like it goes through atleast one apartment.

Scratching my head on this one a little?

I'm thinking it has an earth leakage problem on this cct, and the wet cold weather has pushed it over the edge.

Any ideas?

Cheers
Nathan

 

[westward10]

Does it need the rcbo.

 

[Octopus]

Disconnect lights and IR the cables?

 

[Pete999]

Evening,

Visited a site today for an external lighting fault, bollards to be specific.

The circuit contains six bollards and a contactor brought in via a photocell.
Bollards sited around a mill conversion 4 to the front and 2 to the rear.

Protected by a 6A mem rcbo

They rcbo trips whenever the contactor de energises if all the bollards are in cct, if isolate the two to the rear the trip does not occur.
No signs of water ingress.on most bollards, ir testing on the accessible cabling to the rear appears ok, ir tested n-e ok,
The two bollards to the rear show signs of water ingress, had those in bits and checked the connections replaced corroded lamp holders and terminals (bollards are just contain lampholders via fused terminals, no gear in there thankfully)
As soon as any load is added to the rear bollards, it trips.
I can't access all of the cable run to the rear bollards as it's within the mill walls and looks like it goes through atleast one apartment.

Scratching my head on this one a little?

I'm thinking it has an earth leakage problem on this cct, and the wet cold weather has pushed it over the edge.

Any ideas?

Cheers
Nathan

Is the rcbo tripping on a fault or is it the cb part that's causing the trip, ie fault or overload?

 

[Strima]

What about L-E IR? And as above, RCBO needed?

 

[buzzlightyear]

why don't you disconnect the contactor to see if it is that.

 

[Pete999]

why don't you disconnect the contactor to see if it is that.

Lights won't work if he disses the contactor

 

[nathz29]

Fault not on overload, cct will energise and the trip only occurs when the contactor de energises, all points to an earth neutral fault in my head but can't isolate it

 

[buzzlightyear]

so what are the IR on testing ,

 

[nathz29]

I could take the contactor out, but it only trips when the rear bollards are in cct, the remaining 4 bollards are controlled and function via the same contactor.

 

[Pete999]

Fault not on overload, cct will energise and the trip only occurs when the contactor de energises, all points to an earth neutral fault in my head but can't isolate it

Poor Neutral connection somewhere, done any earth leakage clamp testing??

 

[nathz29]

L-E ir is ok too, all ir results around 30M ish.

Havnt done any earth leakage testing as I forgot my clamp!

 

[buzzlightyear]

by passing the contractor would be better and go from there .
do a IR first and leave the RCBO in and see where it takes you.

 

[static zap]

Don't rule out leakage in Photo cell ,
(that you may be reluctant to IR too heavily)
--Sounds marginal somewhere,
+ Spike from contactor !
..Hence like try without contactor comment...

 

[buzzlightyear]

do you know static. you might be wright on the photo cell.

 

[Octopus]

Are they all LED's - could it be start up current?

 

[nathz29]

All CFL lamps
I did consider the photocell but as an after thought after I'd left the site,
all good points thanks. I'll be revisiting next week couple of additional items to check on site and then I'll be back onto this one.

 

[buzzlightyear]

keep us informed on this one because I will be biting my nails .

 

[nathz29]

I know its enthralling isn't it....

 

[buzzlightyear]

they say two heads are better then one trying figger things out.

 

[Toneyz]

What lamp is in these bollards

Are they all LED's - could it be start up current?

The OP is saying de-energising.

 

[Toneyz]

What lamps are in these fittings?
What type of rcbo is it B,C.
Have you tried disconnecting the photocell and switching through a standard switch?

 

[buzzlightyear]

What lamps are in these fittings?
What type of rcbo is it B,C.
Have you tried disconnecting the photocell and switching through a standard switch?

we will have to wait for the post mortem
I'm afraid.

 

[Octopus]

What lamp is in these bollards

The OP is saying de-energising.

But he does say as soon as any load is added. ....

 

[Pete999]

Clamp the circuit to see what the current draw is.

 

[static zap]

( Daft thought do check contactor is
switching Live , not the other one !)
....Heat steams things up then ....

 

[Pete999]

( Daft thought do check contactor is
switching Live , not the other one !)
....Heat steams things up then ....

good point static

 

[westward10]

I would like to know If the rcbo is actually required.

 

[static zap]

I would like to know If the rcbo is actually required.

No Ants were harmed by this install !

 

[nathz29]

It's a type b rcbo, more good ideas, many heads better than one on this one.

Staring at a cct in the cold today was probably not a good idea, the street lamp heads on due to swap tomorrow might be getting kicked into touch at this rate too!

 

[westward10]

I would still like to know if the rcbo is required.

 

[Deleted member 26818]

I would still like to know if the rcbo is required.

Not according to BS7671.
However it is a requirement of BS7671, not to leave the installation less safe.

 

[Toneyz]

OP can you confirm the tripping of rcbo is it when the lights are switched on please.

 

[nathz29]

Only when switching off and only when, bollard (s) to the rear of the property are in cct.

 

[westward10]

Not according to BS7671.
However it is a requirement of BS7671, not to leave the installation less safe.

Why would it be less safe if an alternative device provides fault protection. If it is a TN system and installation methods permit an rcd may not be required for additional protection and would be compliant with BS7671.

 

[Deleted member 26818]

Why would it be less safe if an alternative device provides fault protection. If it is a TN system and installation methods permit an rcd may not be required for additional protection and would be compliant with BS7671.

It’s not a matter of compliance, it’s a matter of safety.
Is a circuit more safe because it has RCD protection, no safer or less safe?

 

[Des 56]

Maybe the contactor is disconnecting the live and neutral slightly out of sink,one is opening before the other causing a momentary imbalance that the Rcbo sees as a earth fault

 

[westward10]

It’s not a matter of compliance, it’s a matter of safety.
Is a circuit more safe because it has RCD protection, no safer or less safe?

If a non rcd protective device provides overcurrent and fault protection without the need for additional rcd protection it is fully compliant.

 

[Deleted member 26818]

If a non rcd protective device provides overcurrent and fault protection without the need for additional rcd protection it is fully compliant.

Again it’s not about compliance.

 

[westward10]

Again it’s not about compliance.

If you say so.