Meter Accuracy - leakage

[Mike1966]

Hi Guys

Yes, me again, heres the scenario, customer calls in and they say the property is empty and there has been some units recorded on the meter, we install a check meter and shows the meter to be accurate. I have heard of electrical leakage, not sure if thats the right way to describe it.

The question is how do I explain this to them in an easy way ? And how would an electrician test for this leakage.

 

[Squid]

Are you sure all equipment is turned off, fridge, heating controls etc etc if in doubt pull the main fuse.

 

[Mike1966]

Thats the problem , the customer always tells you there is nothing on

 

[Wilko]

Hi - can you tell us the number of kWhrs that have been used and over what period? There could be a TV amplifier “permanently” wired in the loft (for example) that might use 1 unit per week.

 

[PEG]

Smart meter,by any chance?

 

[static zap]

New property ,does it have a garage ,outside lighting ?

 

[static zap]

Thats the problem , the customer always tells you there is nothing on

And it looks well hoovered inside !

 

[PEG]

And it looks well hoovered inside !

Giggerty

 

[Lucien Nunes]

Leakage in the conventional sense comes from two main sources; resistive leakage due to insulation resistance that is less than infinite, and capacitive leakage from cable capacitance and suppressors in equipment that is connected but switched off. Neither is likely to register on a meter, unless something is seriously amiss.

Capacitive leakage has near zero power factor, so although it can clock up a few milliamps in a large domestic installation resulting in one or two VA being consumed, the real power is more likely to be in the order of a few tens of milliwatts.

Resistive leakage on a system with barely acceptable insulation, say 1MΩ from L-E and L-N, will pass 2x230/1M = 0.5mA, for a power consumption of 230x0.0005 = 100mW. It would take 10,000 hours (417 days) to consume one unit (kWh).

Therefore it is likely to be actual equipment that is consuming the power, such as the aerial amplifier mentioned above, rather than the fabric of the electrical installation. If you were registering one unit per week the load you are looking for would be 1000/(7x24) = 6W, which is typical for a small electronic device that gets mildly warm in use.

 

[Squid]

Pull the main fuse, = zero V's

 

[James]

with the main isolator OFF and the circuit breakers turned on,
Check voltage is 0v on the outgoing L-N of the main isolator.
then check resistance between L-N of the same terminals, if there is nothing switched on then it will read open circuit.
I suspect there will be something drawing power. heating timer, outside light on pir, smoke alarms etc.

 

[Pete999]

Leakage in the conventional sense comes from two main sources; resistive leakage due to insulation resistance that is less than infinite, and capacitive leakage from cable capacitance and suppressors in equipment that is connected but switched off. Neither is likely to register on a meter, unless something is seriously amiss.

Capacitive leakage has near zero power factor, so although it can clock up a few milliamps in a large domestic installation resulting in one or two VA being consumed, the real power is more likely to be in the order of a few tens of milliwatts.

Resistive leakage on a system with barely acceptable insulation, say 1MΩ from L-E and L-N, will pass 2x230/1M = 0.5mA, for a power consumption of 230x0.0005 = 100mW. It would take 10,000 hours (417 days) to consume one unit (kWh).

Therefore it is likely to be actual equipment that is consuming the power, such as the aerial amplifier mentioned above, rather than the fabric of the electrical installation. If you were registering one unit per week the load you are looking for would be 1000/(7x24) = 6W, which is typical for a small electronic device that gets mildly warm in use.

Shut up Lucien, don't complicate the issue lol, in fun, please take it as such.

 

[Octopus]

Hi Guys

Yes, me again, heres the scenario, customer calls in and they say the property is empty and there has been some units recorded on the meter, we install a check meter and shows the meter to be accurate. I have heard of electrical leakage, not sure if thats the right way to describe it.

The question is how do I explain this to them in an easy way ? And how would an electrician test for this leakage.

Maybe give us an idea of the of the recorded usage both meters are showing?

 

[static zap]

..... If you were registering one unit per week the load you are looking for ......= 6W, which is typical for a small electronic device that gets mildly warm in use.

Much higher than this ,and need to check Attic for distinctive "Smell" !

 

[Pete999]

Much higher than this ,and need to check Attic for distinctive "Smell" !

The smell you mention is that from experience or usage?????

 

[Lucien Nunes]

I didn't say anything Pete. Can't talk and chew stub sleeving at the same time

check resistance between L-N of the same terminals, if there is nothing switched on then it will read open circuit.

Not always true for small electronic items. Loads that use a capacitive dropper read O/C to a DC resistance test as do some small SMPSUs, but consume current on AC mains.

 

[static zap]

The smell you mention ....

Certain areas of some towns .(pubs & even high streets these days)

 

[Deleted member 26818]

Check for cheap USB sockets.