RCD tripping - testing for cause

[leolec]

I've had a couple of these jobs now, found a garden shed wired into a ring with appliance flex on one of them - nice job

But the one today is a bit bigger a commercial yard - if it's raining the RCD starts tripping at about 5pm.

So I know I'm looking for and from what he's told me I've got a good idea where - so I'm thinking I need to test the Insulation at that point

Is there anything I should/could be doing?

Who makes a good IP5 upwards CU?

 

[telectrix]

is it water getting at the CU? or is it affecting accessories?

 

[Deleted member 26818]

Let me guess, exterior lighting controlled by a dusk to dawn sensor?

 

[leolec]

I haven't seen the job yet - but what hes said to me was they turned everything off and still can't reset the RCD next day its fine

 

[leolec]

Let me guess, exterior lighting controlled by a dusk to dawn sensor?

Must admit - he did say 5pm as if it was everytime - hadn't thought of that one - I would have thought it would be after an MCB - would the RCD stay tripped if there was a neutral prob?

 

[telectrix]

yes. RCD can trip if neutral fault is present. think, if the MCB is off and you get a leakage from N to E > 30mA, then RCD will trip as current in L will be 0, and there will be an inbalance. as spin says, first check would be external lighting. be careful if IR testing a ptotocell in circuit. do a "soft " test , 250v N/E

 

[malcolmsanford]

Let me guess, exterior lighting controlled by a dusk to dawn sensor?

good shout spin ..................but I raise your sensor with a PIR

 

[telectrix]

good shout spin ..................but I raise your sensor with a PIR

raise your PIR with a taped joint ( outside)

 

[SMB]

Laugh....

I must admit the 5pm tripping time does equate to a dawn to dusk sensor.

Very clever Spinlondon, im impressed.

Leolec, please let us know the outcome of the fault, thanks.

(1 gold star to Spinlondon I reckon).

 

[ian.settle1]

Let me guess, exterior lighting controlled by a dusk to dawn sensor?

Or something supplied via a time clock if it is 5 o'clock every time, a dusk to dawn can vary depending up on the ambient light

 

[SMB]

Yes, very good point Ian, infact its probably more likely that a time clock switching a supply on is the cause, rather than the dusk to dawn idea.

A hive of interesting thoughts is this forum.

Thanks.

(im still impressed with your idea spin, and you do decerve a gold star, but I think Ian might decerve 2 gold stars).

Time clock. Yes!

 

[telectrix]

could even be a time clock and a photocell,

 

[SMB]

3 gold stars to telectrix then......


smile.

 

[Dave_]

could even be a time clock and a photocell,

I second that, allowing better control of the lighting if you know what i mean....

I bet its a fitting with a wee bit of water in causing the problem. As previously mentioned, an IR test will assist in finding the fault....

 

[topquark]

Time activated zoned alarm system could be a possibility as well, but would agree sounds like a timer in the equation.

Would be worth a ramp test to see how much current to trip it and a quick clamp test to know what's already there (before 5pm if poss ).