Earth leakage circuit tripping

Bruthal

M cebee wrote: »

meggering at 250v

between L+N (linked) and E

is how you test with appliances in situ afaik if you're troubleshoooting



but still maybe better to play safe

Yea you just beat me to that, but disconnecting all the neutrals and just meggar each one to earth, then each MCB out terminal to earth also(MCB off), saves linking the N`s and L`s.

The meggar voltage wont really matter in this setup.

Bruthal

2011 wrote: »

I can't link L+N in my iMac or TV. I could only do this with the lead in which case I would not be meggaring the appliance.

250V will be DC.
I have no idea what impact (if any) this would have on different devices and would rather not take the chance!

Your missing the point, L+N is linked at the MCB board, so you are testing insulation resistance of both the Live and Neutral conductor of the circuit to earth.

But they can be tested individually as outlined already, by disconnecting all neutrals, and switching off all MCBs. So now we have isolated circuits, each of which can have their insulation tested to earth to find whats tripping the RCD.

This will also test appliances insulation from their circuit conductors to earth.

High voltages will only have a negative effect on sensitive appliances when applied to their L and N.

2011

robbie7730 wrote: »

Your missing the point, L+N is linked at the MCB board, so you are testing insulation resistance of both the Live and Neutral conductor of the circuit to earth.

But they can be tested individually as outlined already, by disconnecting all neutrals, and switching off all MCBs. So now we have isolated circuits, each of which can have their insulation tested to earth to find whats tripping the RCD.

This will also test appliances insulation from their circuit conductors to earth.

I see what you mean. I have never done this. I am always nervous of meggars and electronic equipment (ever since a fellow apprentice caused untold damage!!)

I would still be reluctant to do this with a computer, TV or similar although they are often double insulated.

Bruthal

2011 wrote: »

I see what you mean. I have never done this. I am always nervous of meggars and electronic equipment (ever since a fellow apprentice caused untold damage!!)

I would still be reluctant to do this with a computer, TV or similar although they are often double insulated.

Wont be any problem once you keep away from meggaring the L and N.

Pc`s, tv`s etc wont usually be a problem anyway for RCD`s, and can be left out of the test anyway.

M cebee

fitting rcbos can help troubleshoot intermittent trips alright

if it's practical to fit them

if there's standing leakage from appliances it might spread it across the rcbos as well and cure the problerm

10.5 mA is the recommended max leakage on a 30ma rcd

and they can trip from 0.5 IdN(15mA)if im not mistaken

Bruthal

Individual RCBOs would solve many problems. They will usually show the problem circuit without having to go testing all circuits.

And they eliminate the accumulative leakage alright.

This is one area where isolators on kitchen hidden sockets can help identify problems there also.

M cebee

the only thing with them is if there's occasional trips on say a B20 rcbo

it could be overload ,leakage or even inrush or starting current in theory

2011

robbie7730 wrote: »

Wont be any problem once you keep away from meggaring the L and N.

Hmmmm.
In theory, yes I agree.

In practice I would be concerned.

If it is electronic and I felt it was a problem, I would disconnect and see if the problem goes or put it on a dedicated RCD.

Pc`s, tv`s etc wont usually be a problem anyway for RCD`s, and can be left out of the test anyway.

Agreed, as they are often double insulated.

2011

M cebee wrote: »

fitting rcbos can help troubleshoot intermittent trips alright

if it's practical to fit them

As a temporary measure to locate a problem it can always be done, it just may not look too pretty.

Bruthal

M cebee wrote: »

10.5 mA is the recommended max leakage on a 30ma rcd

The funny thing about that is, it can reduce the shock a person receives before they trip the RCD from contact with live and earth.


A Neutral Earth short does the opposite, this can increase the shock a person would recieve before tripping the RCD, especially on a circuit that has nothing plugged into it.

Bruthal

2011 wrote: »

As a temporary measure to locate a problem it can always be done, it just may not look too pretty.

Yea it would be a good idea if a circuit is suspected.

M cebee

2011 wrote: »

As a temporary measure to locate a problem it can always be done, it just may not look too pretty.

i wouldn't be taking them back out if i fitted them

Bruthal

Once there is room in the board, and the RCBO has cured the problem.

In the instance here, it looks like a problem on a circuit or appliance anyway.

2011

M cebee wrote: »

i wouldn't be taking them back out if i fitted them

What I mean is that if you have a distribution board that is too full to accommodate extra RCBOs and the customer will not pay/can't pay for a larger board or perhaps there are time constraints or other reasons you could fit several RCBOs on a temporary basis to find a fault.

M cebee

you can do that

afaik it's also ok to use the single mod rcbos with solid neutral pole

on TN 30ma circuits

although they don't seem to be commonly used here
i've never fitted one

2011

M cebee wrote: »

you can do that

afaik it's also ok to use the single mod rcbos with solid neutral pole

on TN 30ma circuits

although they don't seem to be commonly used here
i've never fitted one

I have seen some Square D ones, but they required a very specific distribution board. Something tells me that single mod RCBOs would not be cheap or off the shelf, but I honestly don't know.

M cebee

i dont think they're expensive

M cebee

http://www.meteorelectrical.com/consumer-units_16amp-30ma-sp-rcbo.html

2011

M cebee wrote: »

i dont think they're expensive

Well they certainly aren't common and there must be a reason for it.
I got the Square D ones and the board for free as a sample. It is very high quality and did not look cheap to me. The largest single mod RCBOs that I have seen are 20A. Perhaps there is a size limitation too.

2011

M cebee wrote: »

http://www.meteorelectrical.com/consumer-units_16amp-30ma-sp-rcbo.html

I have not seen this model before.
They may be single mod, but they look to me as though they take up extra space in terms of length. This is also a consideration if you were to purchase this type.

M cebee

http://www.etci.ie/docs/ET214.pdf
http://www.hagerbr.com.au/popup.php?scr=1024&id=84&action=faq

a couple of good links

2011

I like this one:
http://www.etci.ie/docs/ET214.pdf

Must ask Stoner to Sticky it

Bruthal

5.1.6 mentions the bit about neutral to earth shorts after the RCD increasing the shock hazzard. A very simple concept but worth noting anyway.

monkstowngirl

:DHi everyone,
Just wanted to write a quick thank you to everyone who replied and offered help. Really appreciate it!
Turned out to be a faulty cable after all that and everything is right again with the world!
Thanks again!

MrThrifty

monkstowngirl wrote: »

:DHi everyone,
Just wanted to write a quick thank you to everyone who replied and offered help. Really appreciate it!
Turned out to be a faulty cable after all that and everything is right again with the world!
Thanks again!

Sorry for dragging this out, but out of curiosity was it a damaged house mains cable or just a damaged appliance cable, or maybe an appliance incorrectly wired to its plug?!

monkstowngirl

Hi Mr. Thrifty. It was actually a faulty cable to a socket.

Poulgorm

I had a problem, a few years ago, with an ELCB tripping intermittently.

My electrician concluded (eventually) that the ELCB itself was faulty - he replaced it with a new one and it solved the problem.