Nucience Tripping Help

[justjust1]

Hi all,

I am just finishing my Level 3 City and Guilds, 17th edition and Test and inspection at collage.

I have a problem!!!
I have replaced the consumer unit in my house with a Hager split load, with a main switch and 2 RCDs. One of the ring circuits has a large Samsung American style fridge freezer, washing machine, tumble dryer and a microwave (this is all situated in the laundry room).
The last 2 sunday nights the RCD has tripped on that side of the consumer unit. Only the oven (40amp MCB) and the ring circuit (32amp MCB) are on that side of the split loaded board.
I am not really sure when the trip happened but it was some time after using the grill in the oven (40ampMCB) but the MCB did not trip just the RCD. The only other thing i can think that it would be is the fridge giving me nuisance tripping via an earth leakage.

The previous CU was a old re-wirable fuse type! Never had this issue but then i have heard on the grape vine that they are not very sensitive plus it did not have an RCD.

Insulation resistance tests @ the consumer unit are coming back ok!

Anyway i can find out if the fridge is omitting earth leakage?

Anyone have any idea on what i could do to find where the problem is?

Cheers
JG

 

[telectrix]

your problem is probably due to cumulative leakage. fridge and microwave are the worst offenders. you could try ramp testing the RCD, and, if you.ve got an earth leakage clamp meter, try measuring the leakage on that circuit with the various appliances plugged in and out.

 

[justjust1]

Thanks, forgive me but how would this be done? I dont have a clamp meter!!!

 

[Deleted member 26818]

You have to first determine whether it is in fact nuisance tripping, or functional tripping due to a fault.
If it is in fact nuisance tripping, then you should consider placing the cooker on a non RCD protected way, or on the other RCD.
Then see what happens.

 

[justjust1]

@spinlondon

OK, but all my test results are coming out ok! so i know the circuit is alright!!

 

[Deleted member 26818]

You've tested the cooker and every appliance connected to the Ring?

 

[marky sparky]

you could just leave the oven switched off at the board or the d p switch when not in use and see if it the rcd still trips if it does then
its not the oven

 

[telectrix]

try an IR test on each appliance, but do a soft test. short LandN and test to E @250V. this should help trace whichevr has low IR.

 

[justjust1]

@ Spin London
No ive only tested the circuit!
@ marky sparky
Good Plan i will try that!
@telectrix will this not beak the fridge? What reuslt should i get?

To everyone, thanks for this!!! Training does not teach you everything experience is what i need!!!!

 

[ridemx27]

I dont think it will be the fridge or that enough earth leakage should be present i feel it will be an earth fault within the oven or grill, like telectrix said do an ir on the cooker could be the cooling fan which would operate as the oven is turned off ?? sounds like its an appliance of some kind i have had simillar before an it turned out to be as little as a plug in door bell chime

 

[justjust1]

Cool thanks!

 

[Octopus]

Laundry room? Moisture from tumble dryer?

 

[justjust1]

Tumble dryer has not been used for 3 days!

 

[topquark]

The IR test will tell you the state of the wiring. You may well find it's the grill (not the fridge). I've had cases where appliances have PAT tested OK when cold, but when they're in use they then leak. Typical with appliances that utilise the heating effect for their use. Ovens/Grills/Irons/Kettles ... when they first start to break down.

 

[telectrix]

if you link L and N on gthe plug top ( croc clip shorting both out, and the other croc on E, you will not put any voltage across L and N. ergo, not blow fridge, but test at 250V