This cannot be right! 0.8amp in N and 0amp in L

[CliveT]

Hi all,

This is really concerning.

Turned off all breakers in a domestic single phase consumer unit. With just the main switch on I measure a 0.8 amp current in the neutral tail into the consumer unit and virtually zero current in the Live tail. This is using a clamp meter.

One of the lighting circuit neutral conductor is showing 0.6amps with this clamp meter. And again the breaker is off!

Is this weird or have you seen this before?

Please can you offer some advice. Thanks

Clive

 

[Pat H]

Any chance the wiring in the house passes close to next doors wiring?
Could be some inductance maybe?
I'd be tempted to pull the neutral conductors out the CU bus bar while monitoring the current flow. See if it's just one.
Isolate that circuit and see what's happening then.

 

[Midwest]

What supply is it. What were the IR results?

 

[CliveT]

It's a TNS supply.

Yeah I will try ripping out the neutrals to see which circuit to troubleshoot.

The house is lived in and I do not have keys to access rooms to do insulation tests as the moment. But will get round to it once I identified which circuit

 

[Octopus]

Out of interest what are you trying to do?

 

[CliveT]

The lighting circuit needs rcd and since the Consumer unit is damaged and dangerous it was best to change the whole consumer unit. So before powering down and ripping out the old CU. some basic tests to ensure there was no leakage that may trip the rcd and therefore delay outage in the installation. This was when this weird thing happened

 

[telectrix]

fit the new CU and test each curcuit before energising. when yo come to any faulty circuits that trip thre \rcd/s, then investigate further.

 

[Octopus]

The lighting circuit needs rcd and since the Consumer unit is damaged and dangerous it was best to change the whole consumer unit. So before powering down and ripping out the old CU. some basic tests to ensure there was no leakage that may trip the rcd and therefore delay outage in the installation. This was when this weird thing happened

Well then .... time to do some IR tests then

 

[HandySparks]

Hi all,

This is really concerning.

Turned off all breakers in a domestic single phase consumer unit. With just the main switch on I measure a 0.8 amp current in the neutral tail into the consumer unit and virtually zero current in the Live tail. This is using a clamp meter.

One of the lighting circuit neutral conductor is showing 0.6amps with this clamp meter. And again the breaker is off!

Is this weird or have you seen this before?

Please can you offer some advice. Thanks

Clive

Likely to be a neutral-earth fault on one of the final circuits. On TN-S there will be a small voltage difference between neutral and earth. If there's a N-E short, it doesn't take much voltage to push 600mA through.

 

[Midwest]

I was reliable informed by a DNO engineer, that although the supply cable/head looks like a TN-S, in the road outside, or further down the street or nearby, the supply cable will have been repaired, so your TN-S is actually PME. So in reality neutral - earth should be at or near same potential? If it ain't an internal fault, could it just be the clamp meter?

What reading do you get when the live/neutral is clamped?