Voltage drop under load

[tim@fuseboxwal]

Hi, has anyone encountered a similar fault...

TN-C-S supply with old wylex fusebox. Last night, customer experienced total power loss whilst in the shower (electric), nothing tripped and no fuses blown. Customer pulled out fuses to check them and then replaced them all but could only get some lights & TV to work.

I tested voltage on supply side of main switch (220v) in the 'OFF' position and (210v) in the 'ON' position, but then as soon as anything is plugged in, or a light is turned on, voltage instantly becomes unstable, bouncing around between 115v - 180v. Disconnecting the shower made no difference.

I did an insulation resistance test across all circuits and readings are around 48-50MΏ on L-N, L-E & N-E.

I've not seen this kind of fault before. Has anyone else? any suggestions for further investigation would be really appreciated.

Thanks

 

[SparkyChick]

Sounds like a bad connection on the supply side, if the service head is getting hot under load it could be in there. If it's an overhead supply, it could be a bad connection along that route.

 

[tim@fuseboxwal]

Sounds like a bad connection on the supply side, if the service head is getting hot under load it could be in there. If it's an overhead supply, it could be a bad connection along that route.

Thanks, that's very helpful. I'll contact the supply company tomorrow. Cheers

 

[snowhead]

Did you check L-E and L-N at the Main switch

 

[tim@fuseboxwal]

Did you check L-E and L-N at the Main switch

Yes, I tested voltage across both L-N and L-E and the main switch, that's where the voltage loss occurs when any load is turned on.

 

[telectrix]

was that on the incoming side?

 

[tim@fuseboxwal]

was that on the incoming side?

Yes, I was testing on both sides and there was no difference

 

[telectrix]

have the meter monkeys been messing?

 

[DPG]

Dodgy neutral on the incoming supply?

 

[tim@fuseboxwal]

have the meter monkeys been messing?

I didn't see any monkeys, but it was driving me bananas.
[automerge]1586890125[/automerge]

Dodgy neutral on the incoming supply?

Thanks, yes I think it's time to get the supply company in. Cheers