RCD TRIPPING after hoover gets plugged in

[Yanni]

My tenants moved in and they say the rcd is tripping when they plug the hoover in the three rooms in the house but it works ok in the kitchen.

The CU is a split load with two RCDs protecting two sets of circuits.
The kitchen is on a 32A ring circuit where the rest 3 rooms are on a 20A radial.

What are the things I need to check?
The house has just had an EICR performed and all recommendations and critical points were addressed and it passed.

How do I go about tracing the fault.
The only thing I suspect is the previous tenants had an electrician o fit an outside socket on the 20A radial.
I recently had work in the garden...

How do I go about addressing the fault?

 

[pete01]

Did the faulty sockets ever work?

Is it only the hoover?

Sounds like neutral in wrong bar to me

 

[CountryFan]

Anything been hung on the walls recently, eg a mirror? I had this once and the electrician blamed the boiler, but I had pinpointed to the hallway socket and she'd hung a mirror and nicked the cable.

 

[Koolpc]

Tell them to suck it up and buy a new hoover!

 

[Jurassicspark]

Did the faulty sockets ever work?

Is it only the hoover?

Sounds like neutral in wrong bar to me

Either this or a neutral to earth fault.

 

[Ragnar_AT]

I‘d think neutral fault somewhere on the affected RCD. Neutral on the wrong bar would trip both RCDs. A faulty hoover seems unlikely as they‘re pretty much all double insulated.

 

[Harry Bloomfield]

My tenants moved in and they say the rcd is tripping when they plug the hoover in the three rooms in the house but it works ok in the kitchen.

Try plugging alternative items, into the same sockets which trip the RCD - does the RCD now not trip? If no trip, then the vacuum cleaner is obviously faulty. Might it be an older vacuum cleaner, which used an earth?

 

[Murdochcat]

cumulative earth leakage?

 

[Murdochcat]

BTW that EICR is rubbish and it appears to be dated for yesterday - really?

using LIM for all the IR tests is not helpful to say the very least AND there could be low IR that you are not aware of

 

[chivers67]

Yes I looked at all circuits with Limitation on all IR testing, one could at least lower to 250v and do some kind of test on some circuits. With regards to the sockets they should be able to be switched off and End to end resistances have been taken so not sure why no IR.

 

[ericmark]

I have three tools I use with RCD's. The clamp-on meter, the insulation tester, and the RCD tester. But the problem is one is not required to do some of the tests for an EICR, which does seem odd.

So we use the insulation tester to show if there is a leakage, but it uses DC so it does not show inductance and capacitive leakage, it is the only way if the RCD has tripped, but the clamp-on meter lets us see back-ground leakage, which should be less than 30% so for a 30 mA RCD looking at maximum of 9 mA.

However, the ramp test with the RCD tester also gives a good indication of back-ground leakage, so if it trips at 20 mA one would hope less than 9 mA leakage or the RCD would be letting through more than 9 mA, however the leakage and ramp test are not recorded. We should test it does not trip at ½ rating, which should also highlight and high leakage, but often the RCD's are tested with the MCB's turned off, so that does not help.

Since you seem to have a lot of problems with RCD's, the clamp-on may be worth it for you?

To test, you don't need to access any live parts. Seen here, the total leakage for the whole of the house is 8 mA, since split between 14 RCBO's that's not a problem. It I had just one RCD, then would be looking at more RCD/RCBO to spread the leakage.

 

[Yanni]

So yes all the sockets have been working fine for 3 years. The only other thing I suspect one of the issues that the EICR first failed was there were no glands on the cables entering the CU so wondering if after putting the cables back in is what cause the issue.

I will go with a henry hoover and try it out but if it works in the kitchen ring then there might be something that allows it to work on the kitchen ring but not on the downstairs radial.

I will also check for nails on the wall but she said she is moving her stuff this weekend so would she have put nails on the wall before moving her stuff, I don't know.

The problem is she has an 18 year old autistic kid that she leaves him on his own and if anyone is around the property she said he gets panic attacks and rings is mum so I can't fix anything unless his mum is around! I had to stop the gardener from working and rescheduling him because of the kid...

 

[endecotp]

The only other thing I suspect one of the issues that the EICR first failed was there were no glands on the cables entering the CU so wondering if after putting the cables back in is what cause the issue.

That would support the idea that a neutral has been put into the wrong bar, or some other error has been made while reconnecting.

If I were you, I'd take a high power device like a kettle and try it in various sockets and see if it trips.

You shouldn't have accepted an EICR that lacks any IR measurements. Is there a note stating why there are no IR measurements? Did you say, "I'm a landlord and I need the bare minimum paperwork to comply with the regulations", or did you say, "I would like you to inspect the electrical installation and complete an EICR please" ?

 

[Harry Bloomfield]

I will go with a henry hoover and try it out but if it works in the kitchen ring then there might be something that allows it to work on the kitchen ring but not on the downstairs radial.

Perhaps the downstairs radial, lacks RCD protection? You need to check.

I will also check for nails on the wall but she said she is moving her stuff this weekend so would she have put nails on the wall before moving her stuff, I don't know.

Nails, would seem to be an unlikely scenario. If it were a nail or similar damage to a cable, I would expect the RCD to instantly trip.

 

[securespark]

I agree. LIM on all IR readings is unacceptable and IMO constitutes an incomplete EICR. He should revisit the property and complete the EICR correctly.

The three things that you know have changed with the electrical installation recently are:

1. EICR
2. Outside socket
3. Recent work in garden

1. endecot might be onto something. Is just one RCD tripping?

2. How long has this been fitted? Is it damaged or is there ingress of water?

3. What is this recent work?