Consumer unit RCD trips when power cut

[adamst]

Hi,

Our RCD in the consumer unit always trips when we have a power cut. We tend to get lots of very brief power cuts (or at least, brown-outs), maybe one a week or so.

It's getting to the stage where we're afraid to go on holiday as we sometimes come back to a defrosting freezer.

I'm assuming(?) that this doesn't generally happen? And that they may be something we have plugged into the circuit which is causing it, or a fault in the CU? (RCD? MCB?) We have two power rings in the house, and one of them does have a lot of electrical equipment plugged into it, but it's all low power stuff, so doesn't get anywhere near 32amps (PC's, TV's, that type of stuff - But quite a lot of it!).

Any ideas?

Thanks.

 

[ricicle]

A photo of the device in question and the mains position would be a great help.

 

[rjm2k]

Does it happen if you turn off the main power switch then turn it back on? If so, it's a process of elimination, removing a few devices at a time then trying again and working out which (if any) causes the issue. You may find it's something with fixed wiring like an extractor fan, hob, oven etc so don't forget to isolate them if possible. I would try to exclude sensitive equipment before the first power up (computers, tvs etc) just to be safe.

Assuming it is an RCD and not MCB

 

[PrenticeBoyofDerry]

A photo or/and some detail of the device would be helpful, some RCDs do need to be reset after power loss.

 

[adamst]

Thanks guys. I'll try and post a photo this evening, or sooner if I can get my wife to take a photo.

Does it happen if you turn off the main power switch then turn it back on?

I have tried that, although not for a while, and my tests were mostly inconclusive, although that is how I found out which ring was (I think) causing the problem.

If my memory is correct, then I think I got to the stage were I unplugged everything, it didn't trip on power-cycle, then I slowly plugged things in until it tripped on a power-cycle, but once I got to that stage, I tried unplugging things again, and it would still trip - so I couldn't narrow it down to a particular thing.

(as an aside, there aren't any fixed wired things on this ring, the kitchen ring is a different one).

Thanks.

 

[PrenticeBoyofDerry]

So you are talking about an internal circuit fault, rather than a complete power-loss due to a power cut via the supply side?
Common appliances that cause RCD to trip are those that have heating elements, such as oven/cookers, toasters, irons, laundry appliances.
It could be that you have one that is responsible for the trip or an accumulation of earth leakage when a number are connected at the same time.
It could also be that RCD has become faulty, where a ramp test on the device would be advised.

 

[adamst]

So you are talking about an internal circuit fault, rather than a complete power-loss due to a power cut via the supply side?

No. I'm 99% sure my RCD trip is caused by an external power cut, albeit, very briefly.

We have friends in the village (half a mile down the hill) who have the same problem at (certainly some, possibly all) the same times.

So (and this is where my lack of knowledge shows), I'm wondering if there is something wrong within our house which means that when these brief power-cuts occur, the RCD trips, rather than staying on.

I'm pretty sure there is nothing in our house/wiring which is causing the RCD to trip.

 

[PrenticeBoyofDerry]

Is the whole system protected by this device, also acting as an isolator to the whole system?
When open the main isolator to the off position does this also cause the RCD to go into trip mode?
Is there more than one RCD, if so do they also trip?
If not are they of the same type.
Photo and details printed on the device would be extremely helpful.
Some RCDs are passive and some are active, one will trip on power loss at the supply, the other does not.

 

[adamst]

Thanks for the help so far. Here are some pics of the CU:

Untitled

• adamst
• 2 Jan 2014
• 1

Untitled

• adamst
• 2 Jan 2014
• 1

Untitled

• adamst
• 2 Jan 2014
• 1

The left hand side of the RCD is protected.

 

[pgnl]

I am interested in the reply to this too. This same thing happened to us last night. We rarely get power cuts all mains cables locally are underground..

I woke at 4am no power in street, no porch lights on nothing. After an hour I grabbed a rechargeable torch and set off downstairs. By happy coincidence once I had entered the garage (where the consumer unit is located) I noticed the neighbours drive floodlight come on. But our lights didn't.

The consumer unit is a Crabtree model with two RCCBs protecting two circuits plus a double main breaker. The first RCCB has split load and 4 MCBs, the second is none split load and 5 MCBs. Anyway I checked the direction of each breaker including the main one and all were on. I flicked the double main breaker from on to off and back to on again and voila the power came on.

Why is this. What happens if we get a power cut when we are on holiday. All the food in the freezers will perish...

Is this normal for modern RCCBs?


Patrick
Worcs

 

[swampy2]

I am interested in the reply to this too. This same thing happened to us last night. We rarely get power cuts all mains cables locally are underground..

I woke at 4am no power in street, no porch lights on nothing. After an hour I grabbed a rechargeable torch and set off downstairs. By happy coincidence once I had entered the garage (where the consumer unit is located) I noticed the neighbours drive floodlight come on. But our lights didn't.

The consumer unit is a Crabtree model with two RCCBs protecting two circuits plus a double main breaker. The first RCCB has split load and 4 MCBs, the second is none split load and 5 MCBs. Anyway I checked the direction of each breaker including the main one and all were on. I flicked the double main breaker from on to off and back to on again and voila the power came on.

Why is this. What happens if we get a power cut when we are on holiday. All the food in the freezers will perish...

Is this normal for modern RCCBs?


Patrick
Worcs

Can you upload a pic of RCCB/RCD or part no.

 

[pgnl]

Here you go...

Thanks


Patrick

Untitled

• pgnl
• 2 Jan 2014
• 1

Untitled

• pgnl
• 2 Jan 2014
• 1

Untitled

• pgnl
• 2 Jan 2014
• 1

Untitled

• pgnl
• 2 Jan 2014
• 1