Earth Leakage

[Pieter00]

Is an earth leakage faulty if it trips before or after the mA rating stipulated on the earth leakage?

[Talmadge]

I had this discussion with my electrician this morning. In my opinion it is definitely faulty if it trips after, as anything over 100 milliamps becomes lethal. It can also be faulty if it is too sensitive and trips around the 20 milliamps range, however not lethal, I think, it trips too quick and needs to be replaced. Any electricians out there that can shed some more light on this?

[bergie]

i think in sans it says 20 -30ma is acceptable. i need to go back and check.

[Pieter00]

Yes it is acceptable but would if the manufacturer standards stipulates 20mA on it, it must trip on that rating. But what if it doesn't. Even if it's a new earth leakage. Where is the fault?

[Talmadge]

Is it tripping before or after?

[ians]

The earth leakage is faulty if it doesn't trip after 30 Ma or if it trips when all the wiring is disconnected.

[Leecatt]

I had this discussion with my electrician this morning. In my opinion it is definitely faulty if it trips after, as anything over 100 milliamps becomes lethal. It can also be faulty if it is too sensitive and trips around the 20 milliamps range, however not lethal, I think, it trips too quick and needs to be replaced. Any electricians out there that can shed some more light on this?

I had this problem last week, earth leakage and random tripping.
I tested the unit with no load connected and found it was very sensitive and tripped at 21 Milli-amps.
I found another unit that trips at 25 Milli-amps and the problem has gone now.
By the way the acceptable range for any earth leakage unit is between 50% and 100% of its rating as indicated on the unit.
For a modern home that would be between 15 and 30 Milli-amps

[ians]

A common problem with random tripping, surge protection plug tops, they break down under load and cause random tripping.

Another common problem, cut insulation on surfix, I have found insulation cut where the electrician strips the cable and doesn't use tape, it gets moisture in the cut and cause nuisance tripping.

In fact there are so many, a good electrician will identify the problem and repair it and others will find other means to overcome the problem, bypassing a stove is one of the common remedies.

[Leecatt]

See
8.7.12 Operation of earth leakage units

[Leecatt]

This house had various areas from where there were earth leakages. Some where electronic equipment, slight leakage at geysers and borehole pumps and various flourescent lights. Too many to mention here. Eventually it exceeded the 21 milliamps the earth leakage worked at or perhaps the unit had become more sensitive over time, and the only alternative was to raise the threshold of the earth leakage unit.

[Leecatt]

A common problem with random tripping, surge protection plug tops, they break down under load and cause random tripping.

Another common problem, cut insulation on surfix, I have found insulation cut where the electrician strips the cable and doesn't use tape, it gets moisture in the cut and cause nuisance tripping.

In fact there are so many, a good electrician will identify the problem and repair it and others will find other means to overcome the problem, bypassing a stove is one of the common remedies.

This house had various areas from where there were earth leakages. Some where electronic equipment, slight leakage at geysers and borehole pumps and various flourescent lights. Too many to mention here. Eventually it exceeded the 21 milliamps the earth leakage worked at or perhaps the unit had become more sensitive over time, and the only alternative was to raise the threshold of the earth leakage unit.

It is incorrect to remove a stove from the earth leakage protected circuit unless it is connected via a "stove coupler"
See 6.16.3.3 Stove connection.

[AndyD]

It's getting more and more common nowadays where the global cumulative leakage in a house exceeds the 20-30mA tripping threshold. Computers have an acceptable leakage of 1-3mA because of their built-in surge arrestors, same with many switch-mode power supplies like laptops, phone and battery chargers etc. Many people don't understand that the earth on majority of circuits is functional and not only there to prevent shocks through elevated touch voltages. Having a standing leakage of 10-15 mA isn't unusual and it doesn't leave much room for very minor fault currents that wouldn't otherwise be a problem.

Often the only solution is to spread the load through more than one RCD (earth leakage). Pretty soon each circuit should have its own RCBO which is a much better system than just one or two RCD's.



RCBO's are still coming down in size and in price but it would be good practice to install them on the socket circuits if you can fit them in the DB.

[ians]

If the stove is connected to an isolator, there is no need to connect it to earth leakage (we don't use stove couplers in Durban) The only time you have to connect it to earth leakage is when the isolator has a combo isolator socket outlet, like we had in the old days.

[ians]

Andy if anything I do believe in this country, I could see less being connected to the earth leakage rather than more earth leakage units being installed