Earth Leakage

Hi All,

I have something in my house that is causing the Safety Switch (Earth
Leakage Breaker?) in the switch box to switch off.

This used to happen once a week or so, but then I went on Holidays for
a month, and I went around the house and switched off a fair bit of
stuff at the wall before I went, as well as the heaters. Of course,
the power didn't go off once while I was away. Since I've been back
home though, the power is going off once or twice a day.

So, I figure it is one of the things I'd turned off while away, or one
of the gas heaters. I've started going around unplugging things one by
one, but it seems a bit hit and miss.

Is there such a thing as a plug-in earth leakage breaker, that I could
plug one piece of equipment into, and then plug that into the wall,
that would trigger before the main breaker in the fuse box triggers?
Something like this would make it easier to isolate the faulty item
over time

Any other thoughts? Any advice appreciated

Regards

John

 

Yes, made by HPM (electresafe), PDL and Ringgrip among others, easy to
come by, but whether it would trip first is hard to say.

 

Don't rule out it being a power outlet (wall socket) causing the
problem.

Particularly if you've got one exposed to moisture -- or like to wash
your walls with a garden hose.

 

Hello John R,
My next door neighbours had a similar problem. I managed to
isolate the problem to their fridge. The reason I remember is,
I had a long extension lead hanging out the window of my
house going into their house for a month running their fridge
and they wouldn't get off their backsides and find an electrician
to fix the problem. I had to find an electrician and bring him to
their house. Payment I recall was cartons of beer.

There were three of these leakage detector devices fitted to
that house. The electrician removed one and bypassed it.
I remember him saying that it was OK to remove it because
the house was old and they were fitted voluntarily. The
electrician said he would come back and run a separate
cable for the fridge back to the fuse box and refit the leakage
device. I remember him saying that fridges are better off run
on their own dedicated power circuit with no earth leakage
device fitted.

How does that little story help you? Well, put your fridge
on a power circuit without a leakage detector then you
can relax a bit knowing that your food will be OK, while
you find, by trial and error, the appliance that is causing
the problem.

Regards,
John Crighton
Hornsby

 

If the appliance isn't too large you could run it through an isolation
transormer. Better to fix the faulty appliance though. The device is there
to protect you!

Marty

 

Thanks Marty,

I absolutely want to isolate the faulty device so that I can fix it,
there was never any question of doing otherwise.

The problem I have is that most of the suspect equipment is the
computer equipment in the office, ie. several computers, printers, a
scanner etc. It's a PITA to turn one of the computers off for a couple
of days to see if it is the culprit, as they get used fairly heaviliy,
it's easier if I can isolate single appliances while still using them
to identify the faulty item, then I can get it fixed and be done with
it.

Regards

John

 

Thanks Patrick,

I'll give one of them a go

Regards

John

 

Here's my 2cents.

Check your switchboard to see if you have a dedicated circuit such as
for the fridge or freezer that doesn't have RCD protection. (These
days its required on everything). If you do, then go out and buy one
of those portable RCD protectors (they can cost quite a bit however do
come in handy) and run the suspect items off an extension lead plugged
into the unprotected outlet. Use the portable RCD on the extension
lead to try and determine the faulty device over time.

Another point is that some houses only have 1 rcd to do all the
outlets in the whole house, so if you have an item that is slightly
leaking (anything with a heating element will) can add up and cause
the RCD to trip. It is recommeded to have an RCD for each
power/lighting circuit within the house that way if it trips it only
turns off one circuit. Stops the accumulation of slightly leaky
equipment.

In fact there is no reason why you cannot do away with RCDs at the
switchboard and just use GPOs with RCDs fitted, however this is a very
expensive option.

 

Another pretty sure fire method would be to go around and measure the
insulation resistance with a 'Megger' type meter. Anything with a low
reading say below 1 megohm would be suspect. The faulty item would show up
compared to the other stuff. An intermittent fault would not show up with
this test but it would be a logical start.

 

I remember I plugged my electresafe into a shaver socket (which in NZ has
an isolating transformer inside it), for some reason the electresafe blew
up under no load, totally cooked itself.

 

Yeah! Good move. Megger the PC, the printer, VCR and TV. Should help
find the faulty item, or stop them from ever working again

Paul

 

Hi John,

A common cause is the fridge. If the fridge has auto defrost, this often
runs from a timer within the fridge, and operates one / twice a day. When
this turn on it defrosts the fridge and heats up the water to
evaporate it. If the heater has developed leakage, which is quite common,
this will trip a RCD (or Safety Switch).

David

 

YEAH, it was said hoping the operator had a clue about instruments, but then
again they could ask the 'armchair experts' like yourself .

 

But some appliances have a bit of leakage that is perfectly safe.

 

I'd try the fridge, the washing machine and the dryer as likely culprits
from experience. Forget about the printers and computer monitors.. Theyre
usually ,but not always double insulated. They cannot t rip the earth
leakage detector. A megger test with POWER OFF to power points, would be a
good idea, as well as checking your power point with an el cheapo phase
tester to make sure all is well with your power points.
Megger test all appliances that are not sensitive to Meggers. I once found a
temp caravan which was giving trouble with earth leakge due to moisture
building up in winter and bad wiring from extension leads.
Watch out for home owner wiring. It lethal!!!!

 

text cut to save space

the fridge and heats up the water to

Mornin all,

According to some people at clipsal I was speaking to, the toaster is
often likely to trip the RCD. This is even if it is not being used,
just plugged into a power point. The elements are connected to the
neutral all the time and if there is a voltage build up (say when a
fridge starts) some current may leak from neutral to earth in the
toaster.

ANother thing it could be is just cumulative leakage, small amounts of
leakage in a lot of places. It is good practice to install a separate
RCD per circuit rather than one for the entire installation. This
costs more but is much less prone to being a pain. While the RCD's are
rated at a leakage current of 30mA they are usually set to trip at
22mA in the factory to keep them in the middle of the allowable
tolerance.

Like other posters have said, some appliances do leak normally to
earth and having them on separate RCDs can help. Some have caps or
MOVs connected between active and earth too which will cause some
current to flow through the earth.

goodluck finding it

cheers
James

 

Thanks very much for all of the excellent responses so far, the
assistance very much appreciated.

I don't think the fridge is the culprit, it was on the whole time we
were on holidays (a month), and the power stayed on the whole time.
Since I've been back, I've turned on everything that I had turned off
while we were away (2 computers, monitors, printers, speakers, a
scanner, a TV, DVD player, and amplifier, and two central heating
systems, as well as sundry other devices), and the leakage breaker has
started tripping at least once a day.

I don't think it's the toaster either, as we don't actually have a
toaster.

Our house has five seperate power circuits, all fed by one leakage
breaker. It also has five lighting circuits, all fed by another
leakage breaker. There is a seperate circuit for the oven, and it
doesn't have a leakage breaker. I wish I had thought ahead when
building the house an specified seperate leakage breakers for each
circuit, oh well, I might get them fitted later.

Anyway, I may have found the culprit. I had my soldering station
plugged in, but not turned on. I unplugged it yesterday morning, and
the breaker hasn't tripped since then. I'll leave it for another week
and see how I go. The soldering station is just one of those Duratech
cheapies from Jaycar, I've had it for about 18months I guess. I might
pull it apart and see if there is something obviously wrong with it.

Thanks again everyone!

Regards

John

 

<SNIP>

Sorry, I beg to differ. Any device with an SMPS will include an RFI filter
in the power supply, resulting in an earth leakage of 2-5mA. The filter may
be on the power side of the switch. A faulty filter component or multiple
devices connected to one RCD could cause a trip.

Regards, Chas.

 

Residential RCDs in Australia should operate at 30 mA.

Marty

 

** Double insulated devices ( lots of them have SMPS) have only a two core
power lead with no connection to supply earth. Kinda makes earth leakage a
bit unlikely.





............... Phil