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Posted By Topic: Earth leakage breaker

Sep 07 2018 13:02

I am doing a job where I am extending a power circuit. When I checked the board I found it is protected by an earth leakage breaker. I have never seen or worked with them before. Would I have to swap for rcd or is it sufficient?

Sep 07 2018 15:44

Is this a voltage operated ELCB? Does the installation earth connect through the ELCB?

I haven\'t seen one of these in many decades!

A voltage operated ELCB isn\'t considered a satisfactory replacement for a RCD.

Bloody dangerous things giving a false sense of safety.


Sep 07 2018 15:52

I have never ever seen one. I didn’t even know what it was. Tried to google it and apparently they came in voltage or current sensing. How do you know what one it is?
I thought it was some sort of rcbo because it was Fuji electric 240v 20A 30mA. But it’s not an rcd it’s an earth leakage breaker. Just didn’t know if you’d have to change it?

Sep 07 2018 20:36

Here is a photo of the breaker

Sep 07 2018 21:09

they are a very early RCD, available about 1995, i installed quite a few, replace it manly due to most of them failing not longer after installation.

Sep 07 2018 21:24

Ok so they are an rcd? Not an rcbo?

Sep 07 2018 21:48

Jackson Electrical in Onehunga, Auckland, used to sell them. They should be able to answer your questions.

Sep 07 2018 21:51

Put in dozens early on. They are an rcbo. Not aware of any failures with those I\'ve installed....yet

Sep 07 2018 21:53

Cool thanks for that. I have never seen them before. So there is no requirement to replace them? Sounds good

Sep 07 2018 22:08

This is where things could be a little hinky. As its so long since they\'ve been available I cant remember if they\'re type A as required by NZ, they could stay in service under the so called grandfather clause? but the new ppt would have to be signed off under today\'s rules? Meaning upgrade? What do the inspectors say.

Sep 09 2018 09:50

I\'ve done some googling, and this thing only has two terminals each top and bottom for line and load, and therefore it has to be an RCD, not an ELCB. To be a voltage or current operated ELCB there have to be two more terminals, as a \"real\" ELCB is inserted in the earth circuit, so the earth circuit passes through the ELCB.

This is what was dodgy about ELCBs and why they got replaced by RCDs; ELCBs only tripped if the leak to earth flowed *through* the RCD. If a person could get between the live conductor and the soil without being in contact with the installation earth then the ELCB wont trip and they would get shocked, perhaps fatally. This feature also meant that ELCBs were only suitable for protecting whole installations, as splitting the earth routes up to match the load circuits is a near-impossible task.

So although this thing must be a RCD, heavens only knows to what standards (if any) or capabilities it was built to, so in my opinion, it would not be acceptable as protection for extending a GPO circuit.

Disappointed to not see a \"real\" ELCB in the wild after all these years.


Sep 09 2018 11:53

have you tested it\'s function like you will need to if you fit an RCD? be interesting to know the results, clearly if it fails it\'s in the bin though.

Sep 09 2018 12:04

An adequate method of testing an rcd is the test button on the unit itself which I have done and it trips fine. I don’t have an rcd tester and I have no acess to one. Yea it’s a funny one alright. Like I said, it seems to be some sort of rcd or rcbo. But as someone stated before, it is possibly not type A which means anything added on will not comply. Obviously the easiest thing to do is to change it but I didn’t want to if I didn’t have to, and customer is family member so was trying to keep cost down.
And yes I know what everyone will say, there’s no cost on safety etc etc and yes I agree, buuuut no point changing something if it isn’t broken or in this case, if its still an rcd.

Sep 09 2018 14:19

cost blah blah blah, whatever it is they need to respect your trade and just do it, an RCD is less than $40, and it can cover multiple circuits in the house too.

Sep 09 2018 15:37

Does it have another label on the side?
In any case, I would be replacing it, and probably recommending the whole board be replaced.

As far as \"pushing the test button\" goes, yes that\'s acceptable for testing a new RCD that you\'re just taken out of the box, and some other applications, but extending a circuit on that RCD and signing a COC, I would want to test the RCD with a real RCD tester.

Sep 09 2018 15:39

useless images :(

Sep 09 2018 15:39

Third time lucky

Sep 09 2018 16:44

Yip fair call and yea it’ll be replaced. No other labelling on it but it looks like the label you sent through is basically what it is.

Sep 10 2018 10:01

When you say \"It trips fine\", I trust that means you checked it interrupts Active and Neutral...
But the key bit is probably the lack of any evidence of compliance with 3190 and the lack of type marking to suggest it can handle pulsing DC.

Sep 10 2018 13:50

How else can I explain how it trips. You push the test button and the rcbo trips. No voltage in phase or neutral. Breaker is no longer supplying electrical apparatus with voltage. I’m not sure what else I could add to this description?
Have been in contact with a supplier in Auckland that use to sell these. He has assured me they are compliant, although of the older type, and that they are indeed type A. I have asked him to send through declaration or certificate of conformity and he said he will sent it through. Just waiting.

Sep 10 2018 14:51

In your Original post you said you were extending a power circuit , you did not actually say what the circuit was for or what is currently on the circuit .
Is it domestic ? would be unusual to find this ELCB\'s on domestic circuits,if its commercial or industrial and not in an area that is mandated for the use of an RCD then it doesn\'t really matter what type it is .
I\'m pretty sure however that they are type A and the other pics posted tend to support that as well , you can see in the Pic that it say Category A .
I have a number of hazardous area sites that use the same ones,I got caught out with one a couple of weeks ago when I was doing some testing and tripped one with my Duspols and set off the fire alarm and deluge system :)
proved it worked but was a bit embarrassing LOL.


Sep 10 2018 15:51

Yeah it is domestic. In a house switchboard. And yeah I had never even seen one before. It is protecting an existing power circuit.
I can just make out the category A marking on the picture that was sent.
Just waiting for some info onit to be sent through.

Sep 10 2018 16:57

I think what Andrew was getting at was to check whether the N pole actually opens.Just losing voltage doesn\'t prove that both poles are open.
And it\'s the checking -for all-poles-open-circuit that is the most important bit of testing an RCD. The new edition is much clearer on this point in Section 8; but it\'s there in current edition in . And even clearer in ESR 24; ie that any RCD that is required must operate in all live conductors