Its been a shocking experience!

[oldhousescot]

Hi All, hoping someone can offer some advice

My plumber is complaining of receiving an electric shock from the new boiler which has left everyone confused.

Last fri he arrived to commission the boiler, worked on it with no issues but couldn't complete because of a water leak when pressurised. New boiler supplied and when he went to install on Monday he started to get shocks and work stopped.

no electrical changes took place in house between fri and mon.

Voltage pen placed on pipework goes solid red. Electrician came out and tested earth said it was all ok and went away. He didnt receive a shock when holding the pipework. Plumber continued but again started receiving shocks.

Main fuse pulled as not sealed and the lights on pen still solid.

Loads more details but not sure what you experts need to hear, so jut let me know!

Thanks
Huse

 

[1john]

What supply do you have? Are your main equipotential bonding conductors in place, did the electrician prove these?

 

[oldhousescot]

Unsure what you mean by supply, I presume you mean 2 core to fuse board with common neutral / earth.

All pipework to house is plastic and all feed pipes in house are plastic bar those near boiler.

Fist electrician (in whom I am rapidly losing confidence) said no bonding required.

Thanks

 

[1john]

Your gas supply is in plastic?? Are you saying you have a PME supply?

 

[flyingsparks]

Did the sparky do any tests at the fuseboard? Perhaps insulation resistance and External Earth Fault Loop Ze readings? Are there earth wires attached to the copper of the water pipe where your main stop cock is and also onto the copper gas pipe probabily by the meter?

Oh and.......

Main fuse pulled as not sealed and the lights on pen still solid.

Prepare to be *******ed!!!

 

[riveralt]

Is this a combi gas boiler and is it wired via a Fused connection unit to where?

Is it the pipes that connect directly to the boiler that are the issue or is it somewhere else in the house?

If it is the pipes connecting directly to the boiler that are causing the shock then it is possible that the boiler has been wired incorrectly either directly from the FCU or there is an issue with the internal wiring.

 

[xr4x4]

Main fuse pulled as not sealed and the lights on pen still solid.

??

 

[oldhousescot]

Its a grant vortex oil boiler. Oil supply line in copper.

Not sure if its PME or not, no markings anywhere. one cable enters property made of a core to live and an outer armour to a block from which the neutral to meter and earth to consumer unit is taken.

Spark say all was tested but he has said that after fitting new consumer unit about two months ago, only o have left wire strand contacting RCD to non RCD and not allowing for any isolation. Hence my reticence to trust his work.

No earth wires to stop cpck as su[pp[ly and house all run in plastic pipe, amins stop cock also plastic

Not a combi and wired via a double pole 3 mm gap fused connection onto ring installed for the house extension.

Seems to be only the pipes around the boiler though can't say for sure. Boiler wiring has been checked and all ok. As ai say all wellon Fri then come Monday its gone crazy!

Still confused!

 

[xr4x4]

is the oil line to the boiler earthed?

 

[oldhousescot]

no its not directly bonded to anything, though why if all was ok on friday and not Monday would this make a difference?

Should it be?

ta

 

[Taylortwocities]

Should it be?

ta

Yes. The oil feed must be bonded as it could introduce a voltage into the house.

(it could introduce a voltage into the house...)

 

[1john]

get a differnt spark in, as that is something stupid to miss, especially with the fault you have described.

 

[bernardgreen]

My plumber is complaining of receiving an electric shock from the new boiler which has left everyone confused.

What sort of shock was it ?

To get a noticable shock from 230 volts the person has to have two points of contact and the shock lasts as long as the person is touching the two points. If the person is well insulted from ground then touching a live wire is un-like to shock and may go un-noticed. ( as in birds perched on 11Kv power lines ) Do NOT test that out you may accidently earth yourself and then it will be a shock.

Static electricity has a much higher voltage and the capacitive effect of body to earth id effective. But these shocks are very short duration once the charge on the body has gone.

Carpets and clothing in frosty dry weather create much more static electricity than they do on warm days. That might explain the change between Friday and Monday. ( or he had different clothes )

Voltage pen placed on pipework goes solid red.

Voltage pens show the difference between the person holding the pen and the item being tested. They rely on the person being capacitively coupled to ground potential to detect live on a conductor. If the person is close to and there for capacitively coupled to a live wire then their potential can be closer to live than to ground. The pen may then show an earthed wire as live and a live wire as dead.

To test for live use a two lead measuring device with the reference lead to a KNOWN good earth.

 

[oldhousescot]

Hi

The plumber described the shock as not always being there he would maybe be able to grip the pipeowork for up to 20 sec before he would feel the shock.

 

[oldhousescot]

As for the clothes point on both occasions he was wearing std uniform and weather was largely the same, maybe about 3 degrees warmer witha little thaw.

I was aware that the pens do not necessarily show "accurately" and that was why we got the spark back in.

Someone suggested a neutral earth fault within the house but I would have thought that if the main supply fuse was pulled that would mitigate any possible fault within the house and therfore push the fault onto the supply into the property from the REC's transformer?