240volt earth leakage regulations.
Heaven
put on an earth leakage detection circuit. If four years our freezer
has tripped the circuit four times.
Some one told me that the regulations have change so that fridges and
freezers no longer have to be on ELD. Is this true or shoud I get rid
of my freezer?
David Simpson
"GPOs installed in domestic installations shall be protected by residual
current devices with a maximum rate residual current of 30mA.
"The requirement for RCD protection need not apply to:
" a) GPOs used to supply refrigerators or food freezers.
If you don't want the freezer on the RCD, you would need to run a separate
circuit exclusively for the fridge or freezer. My understanding of this rule
is that in general fridges/freezers don't get moved a lot, and the frame
would be reliably earthed, and if they are on the same RCD as an other
circuit which trips, the food in the freezer would be damaged if the trip
was not noticed, (ie you were away).
However a fridge / freezer in proper condition should not trip a RCD. I
would have the freezer checked for insulation resistance with a megger, as
it may have faulty insulation etc.
David.
Heaven wrote in message <36ece738...@news.uq.edu.au>...
Heaven
Russell Bach
On Tue, 16 Mar 1999 22:54:28 +1000, "David Simpson"
<david@aicplDOTcomDOTau> wroti:
Darryl
You were saying......
>
>However a fridge / freezer in proper condition should not trip a RCD. I
>would have the freezer checked for insulation resistance with a megger, as
>it may have faulty insulation etc.
Sometimes you get seemingly random trips, and these are usually put
down to electrical noise. Also I have seen them trip at circuit turn
on, maybe because of some initial surge... I don't really know, but if
you have a power outage, and it comes back on (all these things may be
accompanied by power surges and spikes) then it might trip
unnecessarily and ruin your food.
It is possible, therefore, that the freezer may be perfectly OK, and
the trips caused by other things.
Darryl
Jim (from Oz)
(Darryl) wrote:
>Hi David Simpson,
An RCD works by detecting an imbalance between active and neutral,
it would be very unlikely to be affected by any surge currents. If the
freezer is causing a trip then, almost certainly, there is a leakage
current to earth occuring in the freezer. Quite possibly the
insulation on the motor windings is breaking down slowly and
allowing a leak which may be worsened in conditions of high humidity.
As David Simpson, who clearly knows his electrical regs, said,
have it checked with a Megger (A high voltage tester which will
detect most insulation problems, any electrician will have one).
There is a safety issue here too which should not be ignored.
Jim
David Simpson
I think you are confused by the difference between an ELCB, and a RCD.
An ELCB, as defined in appendix F of AS3000-1991, is a voltage operated
earth leakage circuit breaker. This operates on a completely different
principle to a RCD, (residual current device). A voltage operated ELCB
operates by monitoring the voltage rise of the main earthing system in
respect to an auxiliary earth electrode. If the voltage difference exceeds
the operating level of the relay, typically 20 volts or so from memory, the
ELCB will trip and isolate the supply. The old ELCBs were often combined
with a main switch. Voltage operated ELCBs are typically found in older
installations. They are not normally used today, as they are not compatible
with an MEN system.
The big problem with the voltage operated ELCBs where that the protection
level depended on the earth electrodes, which would often be difficult to
maintain, and keep a consistent resistance to ground, and also that they
would be subject to nuisance tripping through various causes. A lighting
strike near the ELCB earthing system would often induce sufficient voltage
to cause a trip. That is why they trip out during storms and power system
surges.
If you have one of these older voltage operated ELCBs (check for two earth
electrodes near your switchboard), I would suggest replacing it with a
modern RCD.
A modern RCD is a current based, as was often referred to as a core balance
relay, or a current operated ELCB. The operation of RCD is in no way
similar to a voltage-operated ELCB, and is dependant on earth leakage
current only for its operations. An RCD is connected to the active and
neutral conductors between the supply and the load. These currents pass
through a magnetic core, and normally the magnetic flux balances. If there
is an imbalance between the currents, caused by leakage, the magnetic flux
is out of balance, and the RCD trips. Modern RCDs are very robust and
reliable in operation, and are not normally subject to nuisance tripping.
In my experience when an RCD trips, it because there is leakage current to
earth, which normally indicates a fault, or potential fault. In cases of
fridges/freezers, leakage often comes from the build up of dust etc in the
fridge, which gets wet with the condensation caused by the cold. This with
old wiring can cause leakage. If the leakage current is just below the
threshold of the RCD, the RCD may hold in until a power surge comes, which
will cause the voltage, hence leakage current to rise, and trip out the RCD.
Also old houses can have leakage current cause by old wiring. Also sometimes
if the fridge is turned of for a while, ie during power outage, the
condensation will increase, and may increase the leakage current during when
power is restored.The heat of normal operation will dry out the moisture,
and leakage current will decrease. Sandwich toasters and other appliances
with heating elements can cause this. I have known of a sandwich toaster to
trip out an RCD when cold, and then worked fine once they had warmed up.
Another cause for RCDs to trip, is that some appliances, typically power
line filters, radio frequency interference suppression devices, etc, have
filter capacitors from active to earth. If these capacitors are too large or
faulty, a switch on surge can unbalance an RCD and cause a trip.
Darryl, I would suggest you get the installation checked out. It is not
normal for an RCD to trip on power up. Get an electrician to megger the
installation and check for leakage. Electricity is too dangerous to fool
around with.
David
Darryl wrote in message <36f15adf...@news.aone.com.au>...
>Hi Jim (from Oz),
>
>You were saying......
>
>
>>On Tue, 16 Mar 1999 12:03:00 GMT, dklockrem...@ozemail.com.au
>>(Darryl) wrote:
>>
>>>Hi David Simpson,
>>>>
>>>>However a fridge / freezer in proper condition should not trip a RCD. I
>>>>would have the freezer checked for insulation resistance with a megger,
as
>>>>it may have faulty insulation etc.
>>>
>>>
>>>Sometimes you get seemingly random trips, and these are usually put
>>>down to electrical noise. Also I have seen them trip at circuit turn
>>>on, maybe because of some initial surge... I don't really know, but if
>>>you have a power outage, and it comes back on (all these things may be
>>>accompanied by power surges and spikes) then it might trip
>>>unnecessarily and ruin your food.
>>>
>>>It is possible, therefore, that the freezer may be perfectly OK, and
>>>the trips caused by other things.
>>
>>An RCD works by detecting an imbalance between active and neutral,
>
>That's correct...
>
>>it would be very unlikely to be affected by any surge currents.
>But in practice, I have seen it happen on two different systems. As I
>turn on the main Circuit breaker, the ELCB trips. Reset the ELCB and
>it holds in OK from then on.
>
>>If the
>>freezer is causing a trip then, almost certainly, there is a leakage
>>current to earth occuring in the freezer. Quite possibly the
>>insulation on the motor windings is breaking down slowly and
>>allowing a leak which may be worsened in conditions of high humidity.
>
>Thos *are* the usual sorts of reasons.
>
>>
>>As David Simpson, who clearly knows his electrical regs, said,
>>have it checked with a Megger (A high voltage tester which will
>>detect most insulation problems, any electrician will have one).
>>There is a safety issue here too which should not be ignored.
>
>Sure get it checked out, by all means... better safe than sorry.
>
>Darryl
Moussa El Karakizi
you where saying....
David Simpson wrote in message <36ee...@news1.us.ibm.net>...
>The wiring rules, section 4.14.9 state:
>
> "GPOs installed in domestic installations shall be protected by residual
>current devices with a maximum rate residual current of 30mA.
> "The requirement for RCD protection need not apply to:
> " a) GPOs used to supply refrigerators or food freezers.
>
>
> If you don't want the freezer on the RCD, you would need to run a separate
>circuit exclusively for the fridge or freezer. My understanding of this
rule
>is that in general fridges/freezers don't get moved a lot, and the frame
>would be reliably earthed, and if they are on the same RCD as an other
>circuit which trips, the food in the freezer would be damaged if the trip
>was not noticed, (ie you were away).
>
>However a fridge / freezer in proper condition should not trip a RCD. I
>would have the freezer checked for insulation resistance with a megger, as
>it may have faulty insulation etc.
>
we bought a new fridge about a year ago, 2 month ago the owner of the house
decided to fit an rcd switch to the house, since then the rcd has been
tripping between 6-7 am almost everyday . after 2 month of plugging and
unplugging appliances we traced the fault to the fridge.
the electrician told us to call the tech guy , because the fridge still
under warranty, so we did, the tech. came and told us the following:
*the fridge ( nofrost ) will cause the rcd to trip down, because it go
through a defrost cycle, (is when they switch on the hitting element
etc...), and that cause the rcd to trip down, that what the technician told
us.
yesterday the electrician came over and made a new power outlet with
independent wiring to the mainborad. (I am still crossing my fingers,
hopefully want trip down again.)
moussa