Tripping and car charger

[magnoliafan89]

Hi guys

Been called to a doctors house recently....you know the type that have plenty of money but want to hold off on shelling out.
Intermittent rcd tripping. Quite a dated installation, large house 17 circuits and all protected by a 30ma rcd.

Went to ramp test and it tripped straight away, put it on half, tripped right away, ZS of a socket, tripped right away.
On investigating I found a socket above the counter that was for the cooker hood. This socket wasnt even screwed back and there was plenty of grease. So I disconnected and put it in blocks...so far the last 2 days the client has reported not one single trip.
Then he plugs in his electric car and boom it goes. Now he hasn't had an actual car charging point installed as of yet he just has a Tesla 3 pin standard plug and lead. I haven't had a look at this yet though.

I'm wondering aside the grease when the car is plugged in is it just tipping over the mA? Does it need two rcds covering both boards? Or is there going to be a problem with his car charger?

 

[DPG]

That's a lot of stuff on one 30mA RCD. Has he not got enough money to upgrade his consumer unit??

 

[James]

This is going to need a logical and methodical approach to fault finding.

problem, intermittent rcd tripping.

possible causes
combined earth leakage from several circuits
one device causing intermittent leakage
E-N fault somewhere
faulty rcd
poor IR on one or many circuits

I would be considering after doing the obvious checks for IR and shorts between L & N on the circuits.

adding a temporary board with separate rcd and breaker.
move the socket circuit that is apparently causing problems to that board

see if problem moves to new board.

it is a case of trying to split the installation up a bit to be able to find the faults.

honestly it is screaming out for a board change with all rcbo breakers.
get your sales patter going and you might be able to send them that way.

£40 per breaker for 17 circ is £680
board to hold them £100

1 day to fit and certify?

compared with multiple call outs for chasing a ghost of a fault.?

 

[buzzlightyear]

his is going to need a logical and methodical approach to fault finding.

problem, intermittent rcd tripping.

possible causes
combined earth leakage from several circuits
one device causing intermittent leakage
E-N fault somewhere
faulty rcd
poor IR on one or many circuits

I would be considering after doing the obvious checks for IR and shorts between L & N on the circuits.

adding a temporary board with separate rcd and breaker.
move the socket circuit that is apparently causing problems to that board

see if problem moves to new board.

it is a case of trying to split the installation up a bit to be able to find the faults.

honestly it is screaming out for a board change with all rcbo breakers.
get your sales patter going and you might be able to send them that way.

£40 per breaker for 17 circ is £680
board to hold them £100

1 day to fit and certify?

compared with multiple call outs for chasing a ghost of a fault.?

the op needs to do a EICR first before he starts on that lot .

 

[magnoliafan89]

the op needs to do a EICR first before he starts on that lot .

EICR?!?!?! nonsense just whack the new board up and any trips after that well....cash in hand and I'm out the door

 

[Baddegg]

EICR?!?!?! nonsense just whack the new board up and any trips after that well....cash in hand and I'm out the door

Yeeeeeeeeeee hahhhhh! Ride em cowboy! ?
[automerge]1574287118[/automerge]
If you not fussed about looks or branding you can get rcbo boards for around £150 including 8-10 rcbos depending on ya buying power and negotiating skills using wholesalers own brand stuff

 

[dmxtothemax]

You may have to investigate the start up surge of the charger,
if it's highly reactive it could trip the RCD,

 

[PEG]

Hi what else has he got plugged in to that DSO?
The charger can pull 3kW,so there may be more than one "stress" on that system...

Time for doctor/spark conference...?

 

[Deleted member 122525]

Regarding the Car charging, dose he charge the car outside, as in is it sat on his drive way or is it in a garage, what is the earthing arrangement in the house tn-c-s or TT. If it is not TT you need to convince him that he need car charging point and you need to make that TT, should there ever develop an open circuit and the earth becomes live. Second the Tesla cars leak a lot more to earth than other cars when charging, about 8-12mA if I remember correctly and they require a different type of RCD, I will look it up in the book and update the post. So that is where the problem could be. Also I think Tesla will install charging points for free when you buy a new car.

 

[Deleted account]

Regarding the Car charging, dose he charge the car outside, as in is it sat on his drive way or is it in a garage, what is the earthing arrangement in the house tn-c-s or TT. If it is not TT you need to convince him that he need car charging point and you need to make that TT, should there ever develop an open circuit and the earth becomes live. Second the Tesla cars leak a lot more to earth than other cars when charging, about 8-12mA if I remember correctly and they require a different type of RCD, I will look it up in the book and update the post. So that is where the problem could be. Also I think Tesla will install charging points for free when you buy a new car.

Quite right.
it needs a b type RCD. They cost around £100- £200 each. So not cheap.
there are lots of articles out there regarding this. I have started a thread on this subject this week as I was in dispute with a manufacturer who have admitted I am correct and have offered my customer £150 for me to supply a B type RCD.

 

[AJshep]

Agree with Pete. Its a bit of a mine field...
I believe Tesla's instructions will tell you that their lower rated charging equipment (up to 32amp) needs a A type RCD as a minimum, anything above this needs a B type.
It's to do with pulsed /full DC leakage overwhelming the coil in general AC type RCDs which can render them useless. Anything that has pulsed DC leakage washing machines, switched mode power supplies (most things with a diode) should really be installed on a A type rcd as when these devices are in use, a general type AC RCD many not operate correctly hindering our "additional protection". Its also worth noting that in the BEMMA guide, A type RCDs cannot be installed upstream of an AC type as the downstream device can be affected, so the OP cannot offer a cheap fix and just put a Type A RCD socket on a circuit protected by a AC RCD

I believe (from what I read or heard from the e5 group) that some car chargers and washing machines with variable speed motors mention in their instructions about protection against high frequency current leakage. So if you follow their guidance we will need F type RCDs or B+ RCDs providing if we need full or pulsed DC protection as well.

 

[magnoliafan89]

Quickly popped round yesterday and did a quick IR of the first CU was getting some funny readings. Disconnected everything and would test N-E on circuits and would get less than 1. But 2 minutes later these same circuits would all clear....