RCD trip

Solarchaser

2nd_time_buyer said:

70sbudgie said:

2nd_time_buyer said:

Solarchaser said:

The 0.03a is the 30ma rcd, but I agree, according to your diagram, the solar isn't on the rcd circuit,  though you would need to remove the front cover WITH MAINS OFF to be sure if it's on rcd or not

Here is the inside @Solarchaser. To be honest, I have no idea what I am looking for. It looks quite "full". The solar is circled. Thanks for all the help, really appreciated.

I've lost track of which conversation is for which installation (cooker or dishwasher). But if this one is still a problem, My thoughts are:

The wiring isn't exactly the tidiest, so it is difficult to see what is going on. This could be contributing to the PV circuit inducing a small current in the earth wire - enough to trip the RCD. This would most likely occur in the morning when the sun goes above the PV horizon, as this would be when the PV makes the biggest step change in output and therefore induce the biggest current in a nearby circuit. Especially on a sunny day.

You would need a friendly electrician to tidy the wiring as it won't be a fun job! Intermittent faults are always the hardest to identify.

@70sbudgie Thanks very much. Yes, this is the cooker. I probably should have started a new thread - apologies OP.

What you have said makes sense. One thing I am a bit confused about is the first time it tripped I was unable to reset the RCD until I switched off the cooker circuit. Does that fit in with what you said above?

Subsequently, I have been able to reset  the RCD without switching off any circuits. It hasn't tripped for a few days now. Intermittent faults are a PITA!

That almost definitely says its a cooker element at a certain level of heat, or at least that's what it says to me.

QrizB

In practice every appliance has an earh leakage current, and individually they might all be safe. It only becomes a problem when there are enough of them connected to a single RCD that the RCD trip current is reached.

Having said that, I'd hope any competent electrician would have an earth leakage tester, and be capable of identifying which circuit(s) and appliance(s) are causing the RCD to trip.

https://uk.megger.com/electrical-tester-contractor-edition/december-2016/earth-leakage-and-the-diagnostic-tool

2nd_time_buyer

Solarchaser said:

2nd_time_buyer said:

Thanks again @Solarchaser. I have checked the earth, it doubles back on itself and is connected - the photo is just not very clear.

The electrician has done checks on the the cooker circuit (and the cooker) and hasn't found any faults. I guess it could be something else other than the solar on the RCD causing the cooker circuit to trip(?). I think he is a bit stumped now.

So it sounds like there are a few options.

1) Swap the cooker off the RCD with one of the other currently non-RCD circuits

2) as above but put the cooker on a RCDO so at least it doesn't trip all the circuits

3) replace the 30ma RCD with a 100ma RCD.

... Any other suggestions?

My gut feeling is that (3) would be easiest and most likely to solve the tripping problem. However, the electrician was sceptical on whether it was allowed to use a 100ma RCD. 

What do you think?

@QrizB yes those 2 circuits seem to be the loft circuit and one of the lighting circuits. I notice that the non RCD circuit on the far right is labelled "water heater". However, as we have a combi boiler I suspect this is an overhang when there was probably an immersion heater. So potentially I could ask the electrician to move the oven to there on a RCDO i.e. (2) above.

@ispookie666 the inverter does not have emergency backup. It is Solaredge. 

Thanks all. I am leaning a lot.

Good news indeed that its connected.

1 thing I was thinking is that in order to connect your solar to the earth bar, the solar guys may have had to move other earth's along the bar, and I guess I'd just be thinking to check all those screw connectors on the bar are tight, and there are no earth wires that are beside the earth bar, but not connected.... purely going on the fact it wasn't an issue until solar was connected.

I know you have said your spark has checked cooker and all is OK, but electric elements are always most likely to cause rcd faults, thinks like irons, washing machines, tumble dryers and cookers, and you can find that they only fault when the element itself gets to a certain temperature, so I'd perhaps advise seeing if you can make it trip, and if you find a way to make it trip, then keep doing it while switching off power to everything else on the rcd one by one until you can prove what it is.

There is definitely no issue with switching to a 100ma rcd, but if that's not the cause, then it will be a waste of money.

I personally would never move anything with an electric element off the rcd, it's main job is to stop you getting a shock.

Putting the cooker on its own RCBO could be a good idea, but then if the cooker is the issue then you will just get that RCBO tripping too.

Thanks very much. I'll get him to investigate further. A separate RCBO for the cooker would at least prevent the whole house tripping hopefully (including the freezer) which could be a problem if we were away.

The strange thing is that it was tripping when with oven disconnected initially. So literally the only thing on the circuit was the cable. So barring rodent damage it is difficult too think what the problem could have been.

Solarchaser

dil1976 said:

Solarchaser said:

ispookie666 said:

@2nd_time_buyer if you have emergency backup power from your inverter you will need another source for earth. 
My knowledge on RCD trip is minimal other than having blamed victron for 6 months only to find the connected equipment was dodgy 🙈

I'm intrigued by this comment, your earth is essentially "your house only" and its there to get rid of any potentially harmful leakage and push it into the ground/ distribute it through everything to dissipate its wattage rather than give you a shock, so your whole house is on one earth, all your copper and metal in the house will be on it... or part of it is really more accurate, all your radiators, taps, electrical wire and it's unique to your house, I've never heard of anything where another earth is suggested, as it would in essence remove the effectiveness of the earth.
The only separate earth I've heard of is in relation to ev chargers and thats more an additional earth to ensure it can carry the full current of ev charging gone wrong. 

My eps uses the house earth, with no issue.

What absolute tosh you are talking here, please do yourself a favour and stop giving incorrect advice. Not every piece of metal work is connected to the main earth, for a start if the plumbing is all plastic that would stop the taps from being connected to it. 

How lovely, thanks.
Yes obviously if the plumbing is using plastic pipe they will not be connected, but its far more common to have copper pipework carrying earth's than plastic pipework throughout the house.
Sure you can argue plastic becoming more and more common, but the most homes still have more copper and this means taps and rads are part of the earth.

And yes 18th edition now states sockets have to have a 30ma rcd, so if you have a socket ring, it shouldn't be increased to 100ma to remain 18th edition compliant 

Solarchaser

2nd_time_buyer said:

Solarchaser said:

2nd_time_buyer said:

Thanks again @Solarchaser. I have checked the earth, it doubles back on itself and is connected - the photo is just not very clear.

The electrician has done checks on the the cooker circuit (and the cooker) and hasn't found any faults. I guess it could be something else other than the solar on the RCD causing the cooker circuit to trip(?). I think he is a bit stumped now.

So it sounds like there are a few options.

1) Swap the cooker off the RCD with one of the other currently non-RCD circuits

2) as above but put the cooker on a RCDO so at least it doesn't trip all the circuits

3) replace the 30ma RCD with a 100ma RCD.

... Any other suggestions?

My gut feeling is that (3) would be easiest and most likely to solve the tripping problem. However, the electrician was sceptical on whether it was allowed to use a 100ma RCD. 

What do you think?

@QrizB yes those 2 circuits seem to be the loft circuit and one of the lighting circuits. I notice that the non RCD circuit on the far right is labelled "water heater". However, as we have a combi boiler I suspect this is an overhang when there was probably an immersion heater. So potentially I could ask the electrician to move the oven to there on a RCDO i.e. (2) above.

@ispookie666 the inverter does not have emergency backup. It is Solaredge. 

Thanks all. I am leaning a lot.

Good news indeed that its connected.

1 thing I was thinking is that in order to connect your solar to the earth bar, the solar guys may have had to move other earth's along the bar, and I guess I'd just be thinking to check all those screw connectors on the bar are tight, and there are no earth wires that are beside the earth bar, but not connected.... purely going on the fact it wasn't an issue until solar was connected.

I know you have said your spark has checked cooker and all is OK, but electric elements are always most likely to cause rcd faults, thinks like irons, washing machines, tumble dryers and cookers, and you can find that they only fault when the element itself gets to a certain temperature, so I'd perhaps advise seeing if you can make it trip, and if you find a way to make it trip, then keep doing it while switching off power to everything else on the rcd one by one until you can prove what it is.

There is definitely no issue with switching to a 100ma rcd, but if that's not the cause, then it will be a waste of money.

I personally would never move anything with an electric element off the rcd, it's main job is to stop you getting a shock.

Putting the cooker on its own RCBO could be a good idea, but then if the cooker is the issue then you will just get that RCBO tripping too.

Thanks very much. I'll get him to investigate further. A separate RCBO for the cooker would at least prevent the whole house tripping hopefully (including the freezer) which could be a problem if we were away.

The strange thing is that it was tripping when with oven disconnected initially. So literally the only thing on the circuit was the cable. So barring rodent damage it is difficult too think what the problem could have been.

Ahh, yeah that is different, if the oven was disconnected it would be hard to see how it could be part of the issue.
Rodent damage to wiring would surely have come up in the sparks earth leak test as QrizB says, assuming he or she used a leakage detector.

The separate RCBO would as you say only trip cooker and not risk other circuits, I'd just be hesitant about paying for moving the circuit off the rcd and onto its own, then finding it was nothing to do with that.
That's said, RCBO's on every circuit that needed an rcd would be nice, just expensive and overkill imo

70sbudgie

Solarchaser said:

ispookie666 said:

@2nd_time_buyer if you have emergency backup power from your inverter you will need another source for earth. 
My knowledge on RCD trip is minimal other than having blamed victron for 6 months only to find the connected equipment was dodgy 🙈

I'm intrigued by this comment, your earth is essentially "your house only" and its there to get rid of any potentially harmful leakage and push it into the ground/ distribute it through everything to dissipate its wattage rather than give you a shock, so your whole house is on one earth, all your copper and metal in the house will be on it... or part of it is really more accurate, all your radiators, taps, electrical wire and it's unique to your house, I've never heard of anything where another earth is suggested, as it would in essence remove the effectiveness of the earth.
The only separate earth I've heard of is in relation to ev chargers and thats more an additional earth to ensure it can carry the full current of ev charging gone wrong. 

My eps uses the house earth, with no issue.

EV chargers don't have separate earths. However, when my EV charger was installed, they had to add extra earth rods. This was to reduce the impedence of the earth network of my house. (Esssentially making it easier for earth currents to be discharged). 

ispookie666

@Solarchaser
If you have EPS you cannot rely on the earthing arrangement as is(TN-S or TN-C or TN-C-S).  You should have a separate earthing arrangement.  If the grid goes down(so will the earthing), and if there is a fault the RCD will not trip and anything metal would be at mains voltage. Hence the need for metal stake or equivalent. Floating neutral is not a nice proposition. Assuming the house to be good enough to provide earthing might be a bit too much as the impede can be variable. 

I hope I'm not talking porking, I have had to read up fair bit on this topic following my inverter failure, which theoretically can be caused by lack of earthing. 

I have diagressed from the RCD topic, but it's really important to fix the problem rather than coverup the problem. 

@dil1976 that was a bit harsh but understand your sentiment.

shibli

So I filled a kettle and tried it on the same plug socket as the dishwasher and no issues with RCD. So now not sure if it's the appliance issue.

Martyn1981

70sbudgie said:

Solarchaser said:

ispookie666 said:

@2nd_time_buyer if you have emergency backup power from your inverter you will need another source for earth. 
My knowledge on RCD trip is minimal other than having blamed victron for 6 months only to find the connected equipment was dodgy 🙈

I'm intrigued by this comment, your earth is essentially "your house only" and its there to get rid of any potentially harmful leakage and push it into the ground/ distribute it through everything to dissipate its wattage rather than give you a shock, so your whole house is on one earth, all your copper and metal in the house will be on it... or part of it is really more accurate, all your radiators, taps, electrical wire and it's unique to your house, I've never heard of anything where another earth is suggested, as it would in essence remove the effectiveness of the earth.
The only separate earth I've heard of is in relation to ev chargers and thats more an additional earth to ensure it can carry the full current of ev charging gone wrong. 

My eps uses the house earth, with no issue.

EV chargers don't have separate earths. However, when my EV charger was installed, they had to add extra earth rods. This was to reduce the impedence of the earth network of my house. (Esssentially making it easier for earth currents to be discharged). 

My understanding is that most EV chargers need (needed) a separate earth. In fact I asked about it when ours was fitted, because (you'll laugh!!!) 'they' didn't fit an extra earth. They explained that that model, didn't require one, but ~90% did. However, that was a year ago, so things may have changed, and more are like the one I got.

Clearly times are a changing, but Solarchaser's comment was correct for most chargers installed in the past.

Do you need an earth rod for an EV charger?

Martyn1981

QrizB said:

In practice every appliance has an earh leakage current, and individually they might all be safe. It only becomes a problem when there are enough of them connected to a single RCD that the RCD trip current is reached.

Having said that, I'd hope any competent electrician would have an earth leakage tester, and be capable of identifying which circuit(s) and appliance(s) are causing the RCD to trip.

https://uk.megger.com/electrical-tester-contractor-edition/december-2016/earth-leakage-and-the-diagnostic-tool

Hiya, I think this was kinda the point of my original reply yesterday. Am I right to understand, and I think you've said this reading your post, that the earth leakages all add up, so it's the sum that's critical (in this situation)?

So the PV isn't necessarily faulty, just adding too much (in some circumstances) for the house on a combined 30mA, hence why I've heard so many times about them needing to be on a 100mA?

If my memory holds true, I think SMA, the goto inverter supplier back 10yrs or so, specifically required 100mA.

My neighbour and friend is a sparky, and I recall him saying that his house has the lights and freezer on a 100mA, so that they are less likely to fail, and you can see what you're doing even if other circuits are down.