Low Earth Voltage in bathroom from bonded fittings

[Deleted member 26818]

Are you saying, that with other circuits switched off the voltage goes away?

 

[Kris Dor]

Yes for some, for instance if I just have the cooker and appliance ring on there seems to be no voltage on rad.

The 3 lighting circuits and Smoke detectors that seem to affect the reading are next to each other on the board but no single circuit kills the voltage.

If I turn off:
Lighting Upstairs
Lighting Upstairs
Smoke Detectors
Lighting Downstairs
Ring Main 1 (this has the spur for the shower)
The voltage reads 0.0v

the main ring circuit that seems to have an effect is not physically close on the board as it's RCCB protected (CU is Contactum split with some circuits not on the RCCB)

(Having said that I can only measure tenths of a volt on the multimeter so it could be 0.02v and my multimeter would read 0.0v)

 

[Midwest]

Hi Mhar, Thanks for your reply, no, the rad is copper all the way so part of the earth, the shower hose is Extraneous as you said the connector is plastic. since the unit is earthed and the rad is earthed and bonded to each other I guess the difference is because the voltage is making the hose conductive through the water. Since water is a bad conductor this would account for only 0.2v on the hose and 2v on the rad (or 2v and 12v after shower is run) I haven't and wouldn't be so mad as to connect an earth from the unit to the hose given that the unit is contained and earthed thus giving the current a path to something metal I can touch in the shower.

Hi Wilko, The tingle is when I'm standing on a tiled floor near the shower.

Midwest, cheers again good advice of course but when I isolate the shower it's still giving this reading, also when I flick the switches in the CU no single circuit seems to be responsible for the voltage, as my sparky turned them of the voltage just slowly decreased.
It seems to be a few circuits combined that make a difference though, the three light circuits and one ring main although it isn't 100% clear.
If I turn off two of the lights on one lighting circuit the 2v goes to 1.9 but if I isolate that lighting circuit it stays on 1.9v

I don't why I'm doing this, because your electrician should have an understanding of these phrases your using, but you may care to watch this video, and perhaps think again about your issue;

 

[Kris Dor]

Im sure he does, thanks for your time Midwest

 

[Kris Dor]

Thanks for the link too, all the best.

 

[Deleted member 26818]

Induced voltage is caused when cables from different circuits are run close together.
The current on one circuit creates a magnetic field, and that field if it intersects a cable from another circuit can cause voltage on the other circuit.
If you turn off the first circuit, the voltage on the other circuit goes away.
This can also happen with copper pipe work.

 

[HandySparks]

I think the OP needs to get some strips of copper and zinc,and sort through the fruit bowl,for lemons...

Are those AC lemons or DC lemons?

 

[HandySparks]

I think the OP needs to get some strips of copper and zinc,and sort through the fruit bowl,for lemons...

Double post.

 

[HandySparks]

(Having said that I can only measure tenths of a volt on the multimeter so it could be 0.02v and my multimeter would read 0.0v)

Just to be clear, this is AC voltage you're measuring?

 

[PEG]

I have just got me old Robin multitest meter out,and if i put one probe on my tongue,and the other on a wet finger,and think about wind turbines...i can get 0.2V

 

[snowhead]

The tingle is when I'm standing on a tiled floor near the shower.

You haven't got underfloor electric heating by any chance have you?
Or was the bathroom floor covered in nailed down plywood before the tiles were put down?

 

[Kris Dor]

Hi,

I have found out this since:
If the earth is disconnected from the shower unit the voltage on the shower hose goes up to 109V AC
When this happens the 3amp fuse in the switched spur doesn't blow and the RCD protecting the Ring main the spur is on doesn't trip either.

Needless to say I've turned it off at the double pole switch.

Is the shower knackered? Why didn't the fuse or RCD trip?

No underfloor heating, yes it is AC voltage, there are undoubtedly a few nails in the floor boards from when the house was built.

 

[snowhead]

If the earth is disconnected from the shower unit the voltage on the shower hose goes up to 109V AC
When this happens the 3amp fuse in the switched spur doesn't blow and the RCD protecting the Ring main the spur is on doesn't trip either.Why didn't the fuse or RCD trip?

There's no reason for the fuse to blow or RCD to trip, there's voltage there, but no current flowing, apart from whatever is flowing through the meter.

 

[static zap]

You have created a potential divider , probably via capacitive coupling half way between N=0V AC
and Live =240 ..then lost a little due to the meter .
(not a very safe test) esp if nervous !
Leakage currents are just that , small currents doing no harm escaping to earth .
( Unless a fault occurs without Earth attached = danger)

 

[Wilko]

Agree with above - but don't use the shower without earth connected as manufacturer intended

 

[CACJL]

I have a hot/cold feed power shower in bathroom, shower frame and a radiator near by.
I'm measuring the voltage difference between the three things and getting the following and wondered if anyone could help. Had two sparky's out who have not thrown any light on it so far.
Shower hose (metal) to radiator 0.2v
Radiator to Shower frame 2v

When I run the shower for 2-5 mins I get these readings
Shower hose (metal) to radiator 5v
Radiator to Shower frame 12v

This voltage then very slowly drops back down to earlier figures over the course of mins/hours rather than seconds (in 5-10 mins it would drop from 12v to 10v)

I have this: Bonding from rad to both inlet pipes of shower
I was advised to do this which is now done: Bonding from earth in shower unit to the pipework feeds and supplementary bonding from pipework to two upstairs light rings which was advice sparky got from NIC

The shower is hot/cold so just a pump from a spur on ring main protected with switched fused 3a and RCCB on ring main circuit

If I switch off the bathroom lights the first 0.2v reading prior to running shower might drop from 0.2v to 0.1v

Nothing on the CU has tripped but there is a tiny spark when sparky took off an Earth from the (rail?) in the CU while he was looking at it.

No single circuit seems to be the cause of the low voltage readings but if everything is off on the CU the reading is 0v.

Any help ideas would be appreciated .
Cheers
Kris

I have a hot/cold feed power shower in bathroom, shower frame and a radiator near by.
I'm measuring the voltage difference between the three things and getting the following and wondered if anyone could help. Had two sparky's out who have not thrown any light on it so far.
Shower hose (metal) to radiator 0.2v
Radiator to Shower frame 2v

When I run the shower for 2-5 mins I get these readings
Shower hose (metal) to radiator 5v
Radiator to Shower frame 12v

This voltage then very slowly drops back down to earlier figures over the course of mins/hours rather than seconds (in 5-10 mins it would drop from 12v to 10v)

I have this: Bonding from rad to both inlet pipes of shower
I was advised to do this which is now done: Bonding from earth in shower unit to the pipework feeds and supplementary bonding from pipework to two upstairs light rings which was advice sparky got from NIC

The shower is hot/cold so just a pump from a spur on ring main protected with switched fused 3a and RCCB on ring main circuit

If I switch off the bathroom lights the first 0.2v reading prior to running shower might drop from 0.2v to 0.1v

Nothing on the CU has tripped but there is a tiny spark when sparky took off an Earth from the (rail?) in the CU while he was looking at it.

No single circuit seems to be the cause of the low voltage readings but if everything is off on the CU the reading is 0v.

Any help ideas would be appreciated .
Cheers
Kris

 

[CACJL]

Is your earthing system TN-C or TN-C-S ?

 

[Toneyz]

This reminds me of when years ago house bashing house been fully tasted ,RCD to sockets only split board supplementary bonding between hot cold ,rad and upstairs lighting circuit. The homeowner complained regarding getting tingle between rad and shower (not electric).Measured it and was 12v did insulation resistance test and found low reading on downstairs lights located it to outside lighting cable that where installed outside light taken down ,cable end cut and tapped up that when rained dampness between live and earth not enough to trip mcb.

 

[Midwest]

Don't just lurk around in the background bak1950, post some replies or start some threads, after all its been over 7 years. By the way sparksburntout is the head teacher on spelling mistakes or bad grammar.