500mA adrift.....

[Jabbajaws]

Hi there everyone,

I was examining my sister's Consumer Unit, the other day and did a clamp meter test on the meter tails and also the earthing conductor.

Line conductor = 8.3A
Neutral conductor = 7.8
Earthing Conductor = 0A

Now l confess to being puzzled on this one as l thought that the line & neutral conductors should be more or less equal. One cancelling out the other.

There is no current flowing through the earthing conductor, so thats a difference of 500mA, that seems to be disappearing somewhere.

Does anyone has a possible explaination for this odd reading that im getting?

Im thinking that there is a loose neutral perhaps, somewhere in the house...

 

[ian.settle1]

Hi there everyone,

I was examining my sister's Consumer Unit, the other day and did a clamp meter test on the meter tails and also the earthing conductor.

Line conductor = 8.3A
Neutral conductor = 7.8
Earthing Conductor = 0A

Now l confess to being puzzled on this one as l thought that the line & neutral conductors should be more or less equal. One cancelling out the other.

There is no current flowing through the earthing conductor, so thats a difference of 500mA, that seems to be disappearing somewhere.

Does anyone has a possible explaination for this odd reading that im getting?

Im thinking that there is a loose neutral perhaps, somewhere in the house...

What make and how good a model is the clamp-on ammeter and when was it last calibrated?

 

[stef]

Hi Jabbajaws,

is it repetitive ? I mean can you confirm it by several measurements?

 

[Graeme Harrold]

Look at the spec of the clamp ans see what the +/- tolerance is. You may also get a slight variance in readings depending on where the cable is within the clamp.

 

[stef]

Could also be an inductive / capacitive load in the circuit? Then the currents won't add up with your clamp meter.

 

[Jabbajaws]

Thanks for the input. Im afriad its a cheapo one l use just for messing about with at the mo. Yes l am getting repetitive readings the same, but as pointed out it could l suppose, be the clamp meter itself and/or also capacitance, which l shamefully admit that l didnt even consider...

 

[ian.settle1]

Thanks for the input. Im afriad its a cheapo one l use just for messing about with at the mo. Yes l am getting repetitive readings the same, but as pointed out it could l suppose, be the clamp meter itself and/or also capacitance, which l shamefully admit that l didnt even consider...

You've answered your own question in the second comment "a cheapo one"