When it rains, this earth leakage trips at night. When it doesn’t rain, it trips about once every two weeks. Where do I start tracing this issue?
lot of times, I have found it to be an outside light fitting that is leaking, letting in rain water/moisture
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I would remove 1 circuit (live & neutral) from the RCD and wire it to a regular CB that is not connected to the earth leakage.
Keep doing this until it stops tripping.
Then just to check add that circuit back to the RCD and if it trips again then you can be pretty sure it’s that one.
Depends on how old the rcd is, I’d start with replacing that.
I had an issue where it would trip as soon as it began raining. Even if it rained for a week afterwards, it would not tripped. I tried hosing different areas of the house with no luck. Replaced the rcd and no more trips.
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Intermittent tripping, that is tripping only when it is raining, at night, the full moon is out, and the dog was chasing a squirrel earlier, are notoriously hard to debug.
In my experience there is only really one way: Testing the insulation with the proper equipment (aka a Megger).
For myself, as I have probably said nauseatingly many times in the past, I bought an earth leakage clamp meter years ago, and these days my first response is to slap the clamp meter on and check the standing leakage.
If the standing leakage is low (below 10mA), and it trips intermittently, then test the RCD (again, bought the equipment long ago, at least it was cheap).
If the earth leakage tests correctly, then you have a leak somewhere, probably exacerbated by moisture or vibration or something. Move on to an insulation test.
If the standing leakage is high (above 12mA), split the DB board into two, each with its own RCD, so that the standing leakage for each is below the nuisance tripping point.
Of course, also check all connections for tightness. I’ve had a tripping RCD on my EV charger two weeks ago… and it was because the copper had yielded and needed a tightening down again.
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If you are comfortable using a Megger, I can borrow you one of mine.
It tripped many times one night and I managed to isolate the breaker that caused the trip. It seems stable now, three days later.
But the breaker is on a lights circuit, and it also includes a light sensor. Lights should not be on earth leakage?
I am out of town now, and did not have time to open the DB. I’ll look at it when I get back.
Thanks for all your responses.
You can remove lighting from E/L but if you want to be aware of any electrical issues then it’s good to include it.
Lucky! It’s a leak on the live side (probably). Leaks on the neutral side suck. You can’t trace them by switching off breakers (because neutral is not disconnected).
It is allowed to not be on an RCD, but there isn’t a hard requirement that it should not be. In my opinion, you should pretty much have as much stuff on RCDs as possible. The only reason not to have lighting on RCDs is because you might have emergency requirements, eg you don’t want the lights to go out and old people to fall and break a hip.
If a person can reach up and touch the light, it should be earthed.
Odds are the leak is in an outdoor lamp, easily accessible.
My last leak was a gecko that climbed into an outdoor outlet. Turns out the tried and true “socket in a York box” needs a bit of gecko-proofing 
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My lights caused neutral-earth faults (essentially the same thing) because they were cloth wires inside metal pipes. The cloth had degraded and bare metal was touching the pipe (and sparking, as the excited electrician informed me once we finally tracked it down).
My 2c: if you know which circuit, just rewire it, it’s cheaper than the alternative.
What’s the latest thinking on which RCD to use in a domestic inverter application?
Depends what the inverter manufacturer tells you. For most HF stuff, these days, we really should start fitting type-B RCDs. Since they are still either unobtainium, or extremely expensive (unless you know which AliExpress seller has a good one), the answer is that you need at LEAST a type A.
A quick perusal of RS Components shows 71 RCDs and RCBOs of type B (although they often misclassify the overcurrent type of RCBOs so it might be less), but the largest one is rated 40A, and costs as much as the EVSE (should you buy this for an EVSE of course). Not much has changed in this department, it seems.
Hager has the CDB563E, which sells locally for just over R10k, ex VAT.
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So, since I’m now going down this rabbit hole…
On AliExpress there is a type B RCD branded “Tongou”. Very affordable, we’re talking 10% of the normal price. And people who have used it seems okay with it. I’d love to see someone do an impulse test on them as well.
@_a_a_a , you have used Tongou in the past if I recall?
No, I probably would not use something from aliexpress for any safety-critical task (where the safety is that of myself or people I care about.)
Perhaps if you could put it in series with another well-known brand, but for some reason I have it in my mind that you cannot do that (although I cannot think of a reason why not.)
But why are you looking into type B, I don’t think it’s a requirement for “low frequency” or “transformer-based” inverters? NVM, I just remembered you have EVs.
Perhaps for the purposes of EVs, the HP(heatpump) variant is better? (they also seem to be cheaper, so there might be a catch?)
I have a Multi-RS these days. That’s not low-frequency “transformer-based” anymore. The manual doesn’t specifically say that a type-B is required. Topology-wise, I know that the battery buck/boost stage is isolated, but the PV is not. It has internal leakage detection, but for 30mA only (and 6mA is already enough to blind an RCD).
Local regulations probably dictate what needs to be installed. Personally, I would prefer a type B… if it wasn’t as much as the inverter.
On the upside, the next revision of the Victron EVSE will have built-in residual current protection, so soon there will be no requirement for a type-B on the EVSE.
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As for ordering from aliexpress, you can get Chint, which is at least locally recognized: CHINT NL210 Type B RCCB 3P+N 4P 2P 1P+N 63A 40A 25A 30MA Protection For EV charging - AliExpress 13
Those specific ones are also sold in the UK, so I guess they have a track record.
Yeah, if your inverter is not galvanically isolated, pull up the NRS-097 report, somewhere in there will be a line that states something to the effect that it must be paired with a Type B RCD to be compliant. (Luckily nobody that enforces NRS-097 has read any of the reports.)
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Of all the rubbish in the electrical space, Chint is probably the least Rubbish. As a replacement for the “Lear” currently protecting the EVSE, it is probably an upgrade!
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Tongou does say their device is certified in all sorts of ways…
Sure, but can they prove it? 