Fuse Constantly Tripping

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Bml4118
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Fuse Constantly Tripping

Post by Bml4118 » Mon Feb 25, 2019 7:51 pm

Please help!

A fuse keeps tripping over and over again. I have 100% narrowed it down to being on the "kitchen sockets" circuit and definitely not to do with overloading or any particular appliance being used.

Believe me, I have unplugged everything in the entire house and it still goes, had one thing plugged in at a time and it still goes, etc. It is not down to one particular socket or thing that's plugged in.

It started randomly in the middle of the night, we discovered it when we woke up. We have not done anything differently recently, nothing new plugged in, no new screws or nails put in walls.

What else could it be please and is it something I can fix myself / if not, will it be a quick/cheap job for an electrician to figure out and complete. I've already wasted £140 today on an electrician who did absolutely nothing.
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Re: Fuse Constantly Tripping

Post by kellys_eye » Mon Feb 25, 2019 8:18 pm

Fridge/freezer - almost guaranteed.
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Re: Fuse Constantly Tripping

Post by someone-else » Mon Feb 25, 2019 8:21 pm

Not being pedantic, but fuses can not constantly trip, they "blow" once and that's it, then they need to be replaced.
So, now we know its not a fuse, please post an in focus picture of what it is that operates / trips / activates.
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Re: Fuse Constantly Tripping

Post by ericmark » Tue Feb 26, 2019 3:40 am

I will guess it is an RCD that is tripping, and yes a fridge/freezer going into defrost mode can if faulty cause them to trip with what seems a random time.

There are three ways of testing a RCD tripping problem.
1) A special meter to test the RCD is not faulty, I would assume the electrician has done that.
2) A clamp on meter to actually measure the leakage.
3) An insulation tester to check for faults, this is the only way without having power switched on.
All there needs meters, the latter on the neutral wire can likely rule out many items, or show them faulty. A good electrician has had it many times before and they will tend to jump to items they have found faulty in the past, so a quicker than a less experienced one.

However there are ways which can help even without all the test equipment, normally a house has more than one RCD, so you locate a socket supplied from other RCD, then use an extension lead to supply things like the fridge freezer, if the fault swaps which RCD has tripped then you have isolated the appliance causing the fault.

It is not always that easy, a neutral earth fault on a toaster may only cause the RCD to trip when some thing with a high load is used like a kettle, but normally one can work out only happens when toaster is plugged in. Often switches on sockets and appliances only switch the line, so even switched off it can cause the RCD to trip, so must unplug items not just switch off.

Picture of what trips will help, as said a fuse as name suggests melts a wire or strip of metal so can not be reset, so we are guess it is either a RCD or RCBO which is a RCD and MCB combined.
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Re: Fuse Constantly Tripping

Post by kellys_eye » Tue Feb 26, 2019 9:39 am

People rarely have the opportunity to disconnect a fridge/freezer for long enough to determine if it is the root cause of a problem but I've come across so many fridge/freezer RCD tripping issues that it's the first thing I go for (check) and it's prven correct 95% of the time.

You could run an extension cable from a different circuit and power the fridge/freezer and see if it trips the other circuit as proof. But a decent electrician should be able to test the fridge to tell you the answer anyway.
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Re: Fuse Constantly Tripping

Post by ericmark » Tue Feb 26, 2019 5:41 pm

A frost free freezer is not easy to test, one would hope the defrost element has the neutral connected all the time so you can test neutral to earth, but line earth will only show the fault when it goes into the defrost cycle, and using an insulation tester on a freezer is not what one wants to do when it is driven from an inverter as it could so easy damage the inverter within the freezer motor.

So likely the best way to test is to supply from a different RCD, it would need some dismantling to be able to test the heater.

The same applies to anything which has a cycle be it washing machine, dish washer, or freezer, unless it shows a fault neutral to earth had to work out if faulty as it will only show the fault when it hits that part of the cycle. But with most other things we can unplug and stop using for an extended time to test.

I am lucky the kitchen is all RBCO fed so easy enough to find a different RCD supply, but many houses it needs an extension lead down the stairs to get a different RCD supply.

And with my three phase freezer and fridge/freezer where the motor is powered from a built in inverter I would be setting the tester to 250 volt not normal 500 volt.
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