What must be on a RCD

So having a problem, load shedding starts all is well, however as soon as the inverter reconnects to the grid the earth leakage trips, assume its transient earth leakages or something… (P.S. not load shedding related as if you kill the mains and reconnect, it does the same)

I have nailed it down the the alarm system AC transformer 220VAC to 16VAC 40VA with those fat Mov’s on L/N L/E L/E, at first I bought a new unit R300 later, same issue, then connected to its own (single circuit direct) different brand RCD (Schneider to Hager) same problem…

I then disconnected the output 16V that feeds the alarm and then disconnected its earth from the plug… To my shock (not literally) and horror its still tripped the EL!!!, how can their be a bypass/leakage to earth in anyway…???

My main question for now I have added a 6A 2p switch to the output of the inverter and this now feeds the transformer (no El) however I took the plug off and directly spiced all the wires, is this allowed as earth is still connected, low amp switch, transformer is completely enclosed in its enclosure.

Everything should be on a RCD, but you can add 2 RCD and split them.

For more discussion on the same topic see

Yup. Well, anything that a little child can get their hands on must be, at the very least. For a modern home, the rule is pretty much that everything should be, and some devices ideally should even have their own RCD.

I think he already did that?

So he’s having the problem I had in my previous house where the gate motor and the garage door opener alone was sufficient to trip the RCD, even though there was nothing in them that remotely that could account for that. The MOVs in my garage door opener (an ET blue) were in the pico-Farad range and couldn’t pass that much current.

Of course @_a_a_a always points out that you cannot necessarily assume everything is 50Hz anymore. Harmonics and stuff, noise. It is pretty hard to argue with the results when you disconnect the earth wire… and it stops tripping!

I fixed it with a very expensive type A-APR (ABB’s name for it) RCD. They are around R4500 now.

Its a grey area for me as not everything in a house is EL protected, have completely isloated every live and neutral in the house and tested just this device and it trips, so splitting wont help, and rather try avoid a UBER expensive El if I can

This is from the draft regs - not sure if they made it into final: The following do not need earth leakage protection:
b) a socket-outlet that complies with SANS 164-4 and that is intended only
for the connection of an appliance for critical application (such as
emergency lighting, a deep-freeze, a burglar alarm, data processing
equipment, or life-supporting equipment);

So it looks like you can have a dedicated circuit for an alarm, which does not have earth leakage?

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So any Type A RCD worth a try?


There is some hope in that.

I tried that too. I tried a type-A… no success. In the end I was so frustrated that I spent the money. I imagine I would have been even more frustrated if that didn’t work, but thankfully it did.

In this case, the socket would have to be a red thing with a flat earth pin on the top to prevent other appliances from using it. That’s what SANS 164-4 is about.

But final note, @Dylan, you are sure you don’t have an actual leak on that circuit? That’s always the first thing. Sparky needs to megger it?

I normally cut out the mov’s on those transformers. For me that worked. You basically loose the “Surge Protection” but never had any further issues on the sites where I did remove them.

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True, its only trips the EL though. We have the plug circuits of the house on 3 separate earth leakages and it tripped on two of them (running an extension lead between points), after that on the solar DB I installed a third new new Hager earth leakage and tested like that with the house bypassed and everything off.

Also all the switches are L+N so when they are off the there isn’t a change (okay maybe small) of any accumulative rcd adding up.

Yeah the unit says, lighting, surge, short bla bla protection.

Its a slightly scary but good idea that will try

So I went this afternoon to get a different type of power supply, some more $$$, however this one works 100% so its the easiest fix I have. Thanks


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OK, I see the triad of MOVs. You could probably clip off/unsolder the two that sits between live and earth, and neutral and earth. Keep the one that sits across live and neutral (it cannot leak to earth, and it will open that polyfuse in the F1 location on a high voltage surge.

Then I see a cap, which I initially thought was a capacitive dropper for the green LED, but it doesn’t look like it under closer inspection. A bit hard to see. It looks like the LED has its current limited by that 56k resistor, and reverse voltage breakdown is prevented by that black diode (most likely a 1N4007). But that means around 5mA through that resistor which is 1.2W of heat… I’m not sure about that assessment!

Then I see an iron transformer in the back. These don’t really create noise or damage easily through surges…

Odds are you can rip out the entire PC-board and just wire the mains to the transformer. You’ll lose the green LED, but most alarms are more than capable of telling you that you have a power failure.

Yeah on the panels at work its generally straight 220VAC in and 24VAC out no other fancy circuit board protections or lights. Just a open transformer.

HAve you separated your Neutrals grid side and after inverter side - they need to be separated , when grid fails the inverter output should then ( only then ) be connected to earth. This can either done with an earth-neutral relay or internally if its a Victron product ( and you have selected that functionality / RSa grid code )