Power keeps tripping out, how to diagnose?

Energize

Energize

Energize

Caporegime
Joined
12 Mar 2004
Posts
29,962
Location
England
So today, the sockets have gone off at least twice, my ups shows 2 blackouts and 1 electrical noise event. I have a decent multi meter, now I have been told that switching to AC microamps and connecting 1 probe to ground and 1 to the device will show current leakage, but is there a faster way of diagnosing which device is causing the fault? We haven't connected anything new to the circuit so certainly nothing is overloaded, so it must be a current leak to ground surely? Any advice would be greatly appreciated as my UPS only has so much charge. :p
 
Is it happening when certain things are on/at a specific point in their cycle?

Our dishwasher was tripping the RCD, but only about 15-30 seconds after power had been restored as it was doing something for a few seconds before turning the heating element on (that was causing the trip).

Highest chance things of tripping are:
External sockets/lights.
The appliances with water and electrics (immersion heater, washing machine, dishwasher, electric shower) so possibly try turning them off/unpluging them. IIRC if it's a fault with a heating element and water you may only see it when the appliance is switched on and using the element as at other times the element won't be "on" so the circuit for the fault probably won't be complete.

After that you have to basically go through everything.
 
Werewolf said:
Is it happening when certain things are on/at a specific point in their cycle?

Our dishwasher was tripping the RCD, but only about 15-30 seconds after power had been restored as it was doing something for a few seconds before turning the heating element on (that was causing the trip).

Highest chance things of tripping are:
External sockets/lights.
The appliances with water and electrics (immersion heater, washing machine, dishwasher, electric shower) so possibly try turning them off/unpluging them. IIRC if it's a fault with a heating element and water you may only see it when the appliance is switched on and using the element as at other times the element won't be "on" so the circuit for the fault probably won't be complete.

After that you have to basically go through everything.
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I had the same issue its a long process as you have to unplug them if thats possible. Some items should have isolation switches which would also work.

Werewolf is quite right its normally the powerful items with elements and other electrics in them. We had a similar issue power kept tripping and then eventually it tripped one more time. Then the oven element stopped working. So it was actually the oven element all the time causing the issue even when it wasn't on. I solved that particular problem by binning the old dual range electric oven ( it was on its way out and ancient ) and buying a new range gas one. Power never tripped again.
 
Werewolf said:
Is it happening when certain things are on/at a specific point in their cycle?

Our dishwasher was tripping the RCD, but only about 15-30 seconds after power had been restored as it was doing something for a few seconds before turning the heating element on (that was causing the trip).

Highest chance things of tripping are:
External sockets/lights.
The appliances with water and electrics (immersion heater, washing machine, dishwasher, electric shower) so possibly try turning them off/unpluging them. IIRC if it's a fault with a heating element and water you may only see it when the appliance is switched on and using the element as at other times the element won't be "on" so the circuit for the fault probably won't be complete.

After that you have to basically go through everything.
Click to expand...

It hasn't happened enough times to narrow it down to that yet unfortunately.

The lights and outside sockets aren't tripping, the sockets in the cellar don't go off (on a separate circuit), oven has it's own breaker, we don't have an electric shower, I'll try the kitchen appliances first as we do have a dishwasher and washing machine on that circuit.
 
We had this recently, turned out to be an oil heater on a thermostat which would randomly trip out. I basically started by unplugging anything on the circut then plugging stuff back in as it was needed. If you have a suspect device you can try and put it on another ring to see if that trips. Good luck!
 
If it's the circuit with the kitchen appliances it might, if it's intermittent be worth trying to run one of them off a different circuit (if you've got two circuits for sockets, or say a cooker circuit with a socket) as long as they're on different RCD circuits as well as different breakers not just different breakers protected by the same RCD.

It might also be worth trying them with a plug in RCD between the appliance and the socket if you can, as from memory the RCD in the fuse box may have a slightly higher trip current than a standalone RCD.
It's been a very long time since I looked into it, but at one point portable RCD's often had a lower trip current because you could get a few ma leakage from some devices which added up on a ring circuit, I vaguely remember one of the science teachers at my school pointing out that the lab breakers were something like 30 or 50ma, because otherwise they got nuisance trips on a regular basis, but plug in RCD's tended to be more sensitive (I can't remember the details but remember looking at the ones we'd got at home and finding him right but that was over 20 years ago).
 
Was there heavy rain when it happened? I say this because I has similar and it turned out to be my outside socket on one occasion and an external security lamp on another, both only happened when it rained.
The only way is to isolate circuits and unplug everything till you find problems.
 
Just to add to Werewolf's list, check your toaster isn't full of crumbs causing an intermittent short. That little **** took me a while to figure out.
 
Another possibility, is that there's another socket in use that hasn't been earthed properly. And the draw of power along with the appliances in the kitchen could be enough to trip the board. My brothers place had this problem. Found the issue out accidentally when I took over a surge protector that showed if it was connected or not. Once that was fixed (eath connection re-established), hasn't had the board tripping again since.
 
Switch all the circuits off;
See if it trips.
If not switch each circuit on individually and see which one trips the system.
Once found circuit that trips, unplug / isolate all power drawing components.
If it trips it's a cabling fault. Best to do a insulation resistance check on the ring/radial or a rcd check.
If it doesn't trip plug in each power consuming component until you get said trip.
 
If it's intermittent it could be a frost free freezer or fridge freezer if you've got either as element goes to earth but only trips if its on the defrost cycle.

If you've got a plug in rcd could plug the thing you think is causing the issue into it.
 
If its just sockets i would say its going to be a process of elimination. Turn off all the sockets to one room at a time and leave it for a day or so and then repeat with each room. There is no quick solution to this unless you get a sparky in. There is also a possibility that the breaker/rcd is damaged in some way.
 
peterwalkley said:
Just to add to Werewolf's list, check your toaster isn't full of crumbs causing an intermittent short. That little **** took me a while to figure out.
Click to expand...

+1

We've had currants (from hot cross buns?) stuck in the toaster, tripping the power before now. I barely ever use the toaster, but I seem to be the assigned magic fairy that empties it of crumbs.
 
I had this 2 weeks ago, just after the heavy rains. after many hours of messing about I ordered a replacement 32amp MCB and that seems to have fixed it. The heavy rain was a total red herring in the end.
 
peterwalkley said:
Just to add to Werewolf's list, check your toaster isn't full of crumbs causing an intermittent short. That little **** took me a while to figure out.
Click to expand...

I think you should replace the domestic goddess or buy her some new cleaning materials or send her on a refresher course on cleaning. :rolleyes:
 
We had similar a while ago... Random nuisance tripping, usually in the evening. Figured out it only happened when the side kitchen window was open
Eventually we solved it. The outside light down the alleyway at side of house (rarely used) was full of water, and was run to a socket. When it was dark the nighttime sensor would let the light motion thingy work.. and when the window was open it would see people/movement and try to turn the light on. POP.

That took some figuring out!!
 
Energize said:
So today, the sockets have gone off at least twice, my ups shows 2 blackouts and 1 electrical noise event. I have a decent multi meter, now I have been told that switching to AC microamps and connecting 1 probe to ground and 1 to the device will show current leakage, but is there a faster way of diagnosing which device is causing the fault? We haven't connected anything new to the circuit so certainly nothing is overloaded, so it must be a current leak to ground surely? Any advice would be greatly appreciated as my UPS only has so much charge. :p
Click to expand...

Fish tank or vivarium heater coming on?
 
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