Mains RCD tripping on larger MCB's

[Linksy5]

Hello
Looking for advise please.
Our mains RCD switch 60A 30mA MK LN 5760 is tripping when either one of my larger mcbs is turned on.
- 32A shower
- 30A sockets
- 30A cooker
I turned every breaker off and individually turned them on. All three mentioned above individually trip the mains RCD.

 

[SparkyChick]

Has your consumer unit recently been changed? Or has it been in a while and this has just started happening?

 

[Pete999]

You need to understand RCDs will not trip on an overload, RCDs trip when there is an imbalance in the current flowing in the L conductor and the N conductor.
Turn ALL the cbs OFF switch the RCD ON and then switch the cbs ON 1 at a time until the RCD trips which ever cb trips the RCD would indicate a fault on that particular circuit, time to call an Electrician.

 

[Richard Burns]

I would suggest that you probably have a neutral to earth fault on one of the circuits protected by that RCD and the resistance of the fault is such that the RCD will not trip until a significant current is drawn from the supply. This would account for the three different circuits all tripping the RCD. The fault could be on any circuit and only testing would determine which circuit

 

[Linksy5]

I moved into the house 2 years ago and it was there then. The issue has just started happening and means I have no electricity currently as cannot turn on sockets
The consumer unit is:
MK sentry unit
CM16
BS 5486 Pt 13

 

[Linksy5]

You need to understand RCDs will not trip on an overload, RCDs trip when there is an imbalance in the current flowing in the L conductor and the N conductor.
Turn ALL the cbs OFF switch the RCD ON and then switch the cbs ON 1 at a time until the RCD trips which ever cb trips the RCD would indicate a fault on that particular circuit, time to call an Electrician.

That's the problem, I had turned them all on 1 at a time and all three MCBs 30A+ cause the RCD to trip so difficult to identify an individual circuit problem.

 

[Pete999]

The fault Richard suggests is a possibility, if it's the socket circuit tripping the RCD unplug everything, switch back on and try your appliances 1 by1 until the RCD trips, there is the culprit

 

[SparkyChick]

Ok, I asked because I've just fixed a house with a similar situation caused by a lack of understanding in the spark who changed the consumer unit.

Could you post a picture of your consumer unit please, making sure to include the LN 5760?

 

[Linksy5]

Ok, I asked because I've just fixed a house with a similar situation caused by a lack of understanding in the spark who changed the consumer unit.

Could you post a picture of your consumer unit please, making sure to include the LN 5760?

 

[buzzlightyear]

I total agree , having a fault on any of the circuits it would advisable to get local spark in to fix the problem.

 

[SparkyChick]

I would suggest you follow the advice from @Pete999 and try unplugging/turning everything off that is connected to the socket circuit and then try just turning that circuit on.

If it still trips, you are going to need the assistance of an electrician and their test gear.

If you were near me, I'd come and take a peek, unfortunately Derbyshire is a bit of a drive.

Edit:- In fact regardless of whether it trips or not, I would suggest you have a look on the forums and try and find a local spark to have a look at it.

 

[Richard Burns]

It might be an idea to try turning off the cooker switch near the cooker and then switching on the RCD and then the cooker MCB with everything else off and see if you still get the tripping.
With only the initial current draw from the capacitance of the circuit the RCD should not trip and I would fall back on the earlier post.
If you do still get tripping then it may be that the RCD is failing, that type is now quite old (and unfortunately difficult to get replacements).

 

[Richard Burns]

I would suggest you follow the advice from @Pete999 and try unplugging/turning everything off that is connected to the socket circuit and then try just turning that circuit on.
If it still trips, you are going to need the assistance of an electrician and their test gear.

It might be an idea to try turning off the cooker switch near the cooker and then switching on the RCD and then the cooker MCB with everything else off and see if you still get the tripping.

SNAP!

 

[Linksy5]

Really appreciate the response I've received from this, great group.
I'll try the advise given to see if we can individually identify something.
My relative is a electrician but unfortunately in the industrial trade.
I reckon they would be willing to have a look at it for me, is there any type of tester I could advise them bring along with them.
Failing that, looks like I will be contacting a local sparky as mentioned I've noticed the RCD not easy to get a like for like now.
Thank you

 

[Richard Burns]

Initially I would be considering an RCD trip test and thereafter, if that was OK, an insulation resistance test individually on each circuit.
Any electrician attending a job should have a tester to do these tests.