External lighting - am I missing something?

[polo1]

Situation - local rugby club. Clubhouse has 18 external bulkhead (Phillips) fittings each using 1 G23, 11w lamp; split into two circuits each on 6amp B type mcbs. Both circuits operate via a contactor & photocell.


Problem - one circuit mcb keeps tripping, holds for three/four evenings typically, then trips.


I've swapped the tripping mcb, checked insu res etc; checked each fitting, no obvious probs.


Any suggestions?

 

[Pete999]

Does the circuit still trip when you swapped cbs over

 

[Deleted member 72666]

What current is being pulled by each circuit? (Shouldn't be much at all!)

 

[Plonker 3]

Has the weather been consistent on each night? Sometime water ingress I to a fitting can case it happen, would explain why not happening every night if only a little bit is causing the fault.

 

[Pete999]

Where's gone?

 

[Marvo]

Try meggering the circuit, as per Dillb could be moisture or even cable damage.

 

[Deleted member 72666]

Where's gone?

Hopefully to do some more testing!

 

[polo1]

Sorry lads, dinner called! Nice to see the sarcasm hasn't reduced in 2014.

I have carried out ins res testing, both circuits were hi and close (actual figures are in my notebook in the van). As mentioned in my OP, a visual check inside each fitting showed no obvious signs of water ingress.

Again as mentioned, swapping/changing the mcb does not stop the tripping. Running current on each circuit is 0.1 amp.

Could a failing ballast cause this?

 

[Marvo]

Are you sure it's not ****ing off the neighbours and they're taking matters into their own hands by switching them off?

 

[polo1]

No neighbours and anyway, the lighting is low level. Now the floodlights, that's a different matter! The sub board is in a locked service cupboard so I don't think anyone's is taking the pi**.

I'm stumped with this and don't want to resort to changing each fitting one by one.

 

[Plonker 3]

Check the inside of the fittings for water ingress

 

[Matthew Jenkin]

have you checked that this mcb is not also feeding any other lighting or feeds the control circuit/photo cell

 

[polo1]

Thanks Dillb, but see #8. I have checked, but no obvious signs of water ingress.

 

[camerabloke]

Have you checked the photocell for ingress?

 

[polo1]

have you checked that this mcb is not also feeding any other lighting or feeds the control circuit/photo cell

Good point. Not as far as I can see and the running current is in line with what I would expect from the perceived load.

 

[Marvo]

Is there any kind of pattern that could be weather related or length of run time related? If the worst comes to the worst and you can't pick any issues up visually or by testing you could split the circuit and see if you can localize the problem that way.

 

[polo1]

Have you checked the photocell for ingress?

Another good point - no I haven't, but I will!

 

[polo1]

Is there any kind of pattern that could be weather related or length of run time related? If the worst comes to the worst and you can't pick any issues up visually or by testing you could split the circuit and see if you can localize the problem that way.

I'm thinking this is what I'll have to do. The weather has been wild of late, but the problem precedes the very stormy/wet weather. Any thoughts on a faulty ballast as a source of overload or am I clutching at straws?

 

[telectrix]

squirrels?

 

[polo1]

Very tasty fried! All of the wiring is internal and tubed or in metal containment.

 

[Marvo]

A trick I've used before is to install a minature fuse holder at each fitting and fit a fairly close rated fuse. They're pretty cheap and you can use a panel mounted type and solder tails to it and insulate with some heat shrink over the top of everything. If it's a rogue fitting that's causing the tripping then the next time it happens it will be the only fitting that doesn't light due to the blown fuse.

 

[Plonker 3]

Marco makes a good point.

Or if you don't have time to do that, Could you not disconnect the circuit half way and see what happens the after a few nights?

 

[Marvo]

It's really quick to install in most fittings if you pre-solder the tails before you go to site and go armed with a handful of Wagos or small sized chocbloc connectors.

 

[guest119]

Fit a transient voltage arrestor in each fitting, pennies each.
Could be killing the mcb when it switches off with voltage spikes, cheap fittings?
Seen it before and it made some mess of timeclock after timeclock till we nailed it. Timeclocks dont like 10kv.
At least the fittings are not from C.E.F.?


Boydy

 

[Plonker 3]

It's really quick to install in most fittings if you pre-solder the tails before you go to site and go armed with a handful of Wagos or small sized chocbloc connectors.

Never thought of that lol

 

[polo1]

Fit a transient voltage arrestor in each fitting, pennies each.
Could be killing the mcb when it switches off with voltage spikes, cheap fittings?
Seen it before and it made some mess of timeclock after timeclock till we nailed it. Timeclocks dont like 10kv.
At least the fittings are not from C.E.F.?


Boydy

Cheers for that ( and Marvo & Dillb too!), I was running out of ideas. Good few things to try.
The fittings are Phillips and are original to the build. The other half of the lights/building have been fine.
I normally quite enjoy fault finding, but this one is starting to grate.

Thanks again all for helpful contributions, much appreciated.

 

[Marvo]

No probs, let us know how you get on.

 

[Deleted member 72666]

Is the photo cell and contactor fed from the mcb that's tripping?

 

[polo1]

Is the photo cell and contactor fed from the mcb that's tripping?

The contactor (2 pole) is fed from the two 6amp mcbs, in turn feeding each of the lighting circuits. Have to check where the photo cell takes its feed from.

 

[Dizzy_Maskell]

Not a lose or snagged cable I've found this before all ok and IR clear but on occasion it would trip.
Turns out it was the slightest nick on the incoming cable someone had caught the insulation and every now and then it would touch the metal case of the fitting.
Although you said conduit and the ones I encountered where flex and so guessing bit more freedom to move

Just a suggestion

 

[polo1]

Thanks for the suggestion DM. By way of an update, I insulation res tested the circuits to death, checked and remade all the connections at fittings & the sub board and have not had the mcb trip in 10 days. Permanent fix? Only time will tell, but I do know that I have still not found anything that I think may be the cause!

 

[Deleted member 72666]

Could be that it may not have been windy for 10 days.... just a thought!