Strange RCD tripping...

[londonfire]

Have had a call from a regular customer about their RCD TRIPPING.

Strange thing is it has tripped every Monday between 6-6:30 am for the last month.

The property has recently had new kitchen appliances (all high end Neff)

Has also had the meter changed to a smart meter.

My initial thought are central heating however I would expect the same fault everyday.

The board is a 16th edition single RCD board with 10 circuits on the RCD side all a mix of 16 and 32a.

My thinking is the add two RCBOs on the non RCD side and move 2 circuits at a time (with the most recently worked on circuits first. Then most probable) until the offending circuit shows it's self!

Then once rectified move the two circuits with fridges on them to protect them from over circuits tripping in the future specially if the customer is not home on a Monday to reset it!

Any other thoughts would be much appreciated

 

[Plonker 3]

What testing have you carried out on the RCD?

 

[londonfire]

When I fitted a new radial circuit for the microwave and steam oven The RCD was tested at x1 and x5 and tested with very good trip times (however didn't carry out a ramp test) the earthing arrangement is TNCS and all bonding to 17th edition

 

[Plonker 3]

When did you test it? Would be well worth tsting it again even just to eliminate it.

Sounds like there is something connected to a time clock somewhere.

 

[londonfire]

About 2 months ago.

Time clock or programmer was my thought too. Customer claims the central heating is programmed differently for Monday-Friday than the weekend and does come on around the time of the tripping so will start there when I go to investigate.

 

[Sintra]

Had something similar happen to a friends elderly relative. She had a few outdoor pir fittings spurred of her sockets and when the bin men came round every week they triggered a faulty fitting and tripped the RCD. Turned out to be more detective work than fault finding.

 

[HappyHippyDad]

Depending on how capable the customer is you could ask them to try and reset the RCD as soon as it trips, if it doesn't allow itself to be reset they could try turning off one breaker at a time and see if it does allow itself to be reset when a certain MCB is switched off. It might not show up but its worth trying before you start chopping and changing the CU with RCBO's.

Or you could arrive at 5.50am monday morning and do it yourself :smile5:

Also, it's unlikely anything will show up on an IR test because it's not a permanent fault, but I'd still do a quick global IR just in case something does show up.

 

[londonfire]

Forgot to say also resets straight away too.

 

[HappyHippyDad]

Forgot to say also resets straight away too.

Oh dear! RCBO's it is then... and some detective work!

 

[SparkyJoe]

Have had a call from a regular customer about their RCD TRIPPING.

Strange thing is it has tripped every Monday between 6-6:30 am for the last month.

The property has recently had new kitchen appliances (all high end Neff)

Has also had the meter changed to a smart meter.

My initial thought are central heating however I would expect the same fault everyday.

The board is a 16th edition single RCD board with 10 circuits on the RCD side all a mix of 16 and 32a.

My thinking is the add two RCBOs on the non RCD side and move 2 circuits at a time (with the most recently worked on circuits first. Then most probable) until the offending circuit shows it's self!

Then once rectified move the two circuits with fridges on them to protect them from over circuits tripping in the future specially if the customer is not home on a Monday to reset it!

Any other thoughts would be much appreciated

I think the timing gives you the biggest clue

 

[Octopus]

Do you have a clamp meter?

Before you start moving circuits off the RCD see if any of the existing circuits have a high leakage?