Fuse box tripping

[GeordieAndy14]

We've recently moved house and the electrics in this one are chaotic to say the least. We have 3 separate consumer units! Most of the house is on 1 one of them, but occasionally when using power intensive devices such as lawn mower or power tools, it'll trip the fuse. However, it isn't tripping the breaker on the one the device is on, it's just tripping the main fuse for the whole consumer unit (apologies if my terminology is all over the place here, by no means an expert). And my bigger concern is that it's not even tripping the consumer unit it is on.

So for example, the socket I connect the lawn mower to is fuse 1 on consumer unit 1, but it'll trip the whole of consumer unit 2 instead of 1 so the lawn mower never stops. I only notice when i come back in and find that the lights aren't working.

Any ideas how this is happening and how worried i should be about it? We're going to get an electrician to come have a look at it but wanted to get a general idea here of what might be going on first.

Cheers

 

[Harry Bloomfield]

However, it isn't tripping the breaker on the one the device is on, it's just tripping the main fuse for the whole consumer unit (apologies if my terminology is all over the place here, by no means an expert). And my bigger concern is that it's not even tripping the consumer unit it is on.

The item which is tripping, sounds like it is an RCD protecting the entire consumer unit. That suggests the item you are plugging in when it trips, is faulty. Take a photo and indicate on the photo the item which is tripping.

 

[GeordieAndy14]

Cheers for the reply. Have attached a photo of the consumer units.

So I may be wrong but I don't think it's the appliance which is faulty. It's happened with various different things.

The latest incident was when using the lawn mower which is on the fuse circled in red, so i would have expected either that red breaker or the yellow one to trip if there was a problem. However, it's actually the one circled in green which is tripping, and therefore didn't stop the power to the lawn mower!

Does that make sense?

 

[Harry Bloomfield]

The item circled in green, is an RCD. An RCD measures the current flowing through both L and N, should there be any difference in the current then it is designed to trip - based on the assumption that there is a leak from one, to earth. The yellow button allows you to test and simulate such a leak, prove the RCD is working.

Finding the cause of the tripping, without test equipment, can be quite tricky. Bear in mind they trip on a certain level of leakage, probably 30mA, the the leakage could involve the leakage of several circuits, or appliances adding up to more than the 30mA - hence your confusion. It can even cause the experts some problems to trace such problems.

I would suggest what you need is to find a well equipped electrician, with experience in tracing such issues.

 

[opps]

.... I am not an electrician..... but I wonder why the mini circuit breaker for the outdoor plug is only 10 amps.

 

[GeordieAndy14]

I don't know if this makes it better or worse but there's a 13amp fused switch before the outdoor plug...

 

[GeordieAndy14]

Thanks Harry. That's sadly what i was afraid would be the answer. Worried i'm going to end up spending £££ for someone to investigate but sounds like i might have to bite the bullet

 

[EFLImpudence]

The thing the OP has tripping is a Residual Current-operated Circuit Breaker hence the RCCB printed on it.

 

[chivers67]

Has the RCD feeding the Lawn mower ever tripped? Have you ever pressed the test button on it?

 

[ericmark]

One I made earlier, it seems likely the RCD also called RCCB is the item tripping.

The RCD measures electric in and out, and if they are within 30 mA of each other it assumes all is OK, in the main it is when line leaks to earth they trip, but they can also trip if neutral goes to earth.

With no load with a TN supply neutral and earth are about the same voltage as each other, so even if earth connected to neutral no current will flow, however as the load increases the neutral voltage moved towards the line voltage, so there is now a voltage between neutral and earth, so current can flow between the two.

So any item plugged in even if not in use can cause the problem, so first thing is unplug items not being used.

 

[EFLImpudence]

View attachment 279625One I made earlier, it seems likely the RCD also called RCCB is the item tripping.

...and the RCBO is also an RCD.

The RCD measures electric in and out

Well, not really. It just senses any imbalance, i.e. the residual current, like any clamp meter around Line and Neutral.

and if they are within 30 mA of each other it assumes all is OK,

You are attributing too much intelligence to the device.
If the residual current is more than the limit it trips.

 

[Koolpc]

Every time i took my fuse box out for a walk it would trip!