Tingling feeling in the shower

[ians]

I have another one of these...so far i have checked the following and the problem is still present.

I have checked and secured the main incoming earth...even sanded the lugs and washes to make better contact.

Done a loop impedance test at the meter box...main DB and sub DB,s... 1.3 ohms ( Z= V/2 I) 238 volts/ 2 x 80 amps = 1.49 ohms max

Installed and replaced bonding straps and re terminated the earths on all the geysers.

Done insulation resistance tests on the geysers (all 5 of them)

Gone around the building and secured and added bonding where it had broken off or found loose connections.

Checked the voltage L-N = 238v ... L-E = 237v ... N-E = 0.5 - 3.8 volts (now this concerns me the way it moves up and down)

Did earth continuity tests from the earth bar to the taps o.1 ohms and lower if i check on the copper pipes.

If i do a potential difference test between the taps and outlet/drain (all PVC pipes with metal covers in the shower) ... the voltage ranges from 0.5 volts to 5 volts

[sytcee]

Your elevated NE voltage, are you using an earth external to the installation? Like do you knock an earth spike outside the house and run an extension as your true earth?

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[ians]

Your elevated NE voltage, are you using an earth external to the installation? Like do you knock an earth spike outside the house and run an extension as your true earth?

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I have an earth spike in the ground next to the meter box and a suppliers earth from the road.

[sytcee]

I have an earth spike in the ground next to the meter box and a suppliers earth from the road.

For testing purposes, kindly knock an earth spike away from the supplier's and the one you installed. The idea is test the integrity of your supplier earthing. As a municipal worker , I know many municipal electricians who would appreciate the results of your elevated NE tests.

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[ians]

What did we learn form this little challenge ... a few things :

It is always good to offer a full inpsection report on a building when you get a new customer ... especially if they start refering to you as "our electrician".

Customer dont understand how things can go wrong 6 months or 2 years after you started doing work for them ... they just assume that if you fix one plug in the house ... the entire installation is now safe and up to standard ... no matter how absurd it sounds ... CYA with an email.

Whatever you do ... DONT ... start telling them their electrical installation is F%^&* ... they dont want to hear it ... rather just make a note and email ... that way you CYA.

I have a few customers who understand ... but in general most cusotmer just think you want to rip them off.

[Derlyn]

Hi Ians

Get called out quite often for this problem.

Have had it at my house as well.

From past experience I can say that 99% there is a bad, high impedance neutral connection somewhere between the installation and the sub station transformer.
The problem is NOT on the installation itself and strange as it may sound, the better the earthing on your installation, the more pronounced the tingling will be.

This problem is more prevalent in areas that have overhead supplies where the connections are exposed to the elements.

If no other residents in the area are experiencing the same, then the fault will be either on the pole supplying the installation or in the roof box.
For underground supply, check the neutral connection in the stubby on the pavement.

I have in the past found a whole street experiencing the same and it was a bad neutral connection on the Municipal transformer.

Good luck.

Derlyn

[ians]

Hi Ians

Get called out quite often for this problem.

Have had it at my house as well.

From past experience I can say that 99% there is a bad, high impedance neutral connection somewhere between the installation and the sub station transformer.
The problem is NOT on the installation itself and strange as it may sound, the better the earthing on your installation, the more pronounced the tingling will be.

This problem is more prevalent in areas that have overhead supplies where the connections are exposed to the elements.

If no other residents in the area are experiencing the same, then the fault will be either on the pole supplying the installation or in the roof box.
For underground supply, check the neutral connection in the stubby on the pavement.

I have in the past found a whole street experiencing the same and it was a bad neutral connection on the Municipal transformer.

Good luck.

Derlyn

I had an issue at home where the live wire broke off the over head line and landed on the metal part of the street light ...jumped in the shower and almost died ...fortunately for me i had not secured the tap with the little screw on the side so as i got hooked up the handle came off and released me.

The house is supplied from an underground cable.

I have done a loop impedance test which indicated that the connections "should " be ok ...if this reading was high ...i would have notified the supplier... which i might still do.

I have even done insulation resistance tests on the geysers to make sure we dont have a bad element.

My concern is the voltage between the drain (PVC) and the taps metal.

[ians]

I think i found the root cause of the problem ... the tingling had stopped once i secured all the earthing points ... secured the bonding and fitted additional bonding outside ... but I believe all I had done is created an easier path for the leakage current.

This week a circuit breaker feeding an outbuilding ... tripped and would not reset ... I opened the DB and disconnected the wiring on both sides ... found all the exposed junction boxes ... but couldnt find the joint between the conduit and the cable at the house ... I couldnt get to the conduit above the DB where it came out into the roof space ... tried opening the roof tiles ... but there was a gutter/channel above it ... eventually I got a long ladder ... managed to get it into the roof space and crawl to the lowest part of the roof space ... the 2 way box wasnt the connection point ... next step was to pull the ceiling down ... after pulling down the second sheet ... we found the conduit to cable joint in the eaves ... removed the cover and there it was ... a dead short between live and neutral.

The plastic connectors which were not crimped using the correct tool had created a loose connection ... causing the wire insulation to melt to a point that the gap was close enough to generate a small current on the earth ... which over time had broken off or come loose in parts of the building ... that tingling problem was stopped ... but the root caue of the problem was present until now.

I cut all the joints in the circuit and crimped them using the correct tool ... slipped some heat shrink over the ferulles and insulation tape to make sure there was no chance of a low insulation resistance ( by the way all the joint were done in round conduit boxes ... even the cable to conduit joints) carried out an insulation resistance test ... all clear (54 meg) 500v and 1000 v ... a 500 volt test was only reuired as it is a 230 v installation ... but did the 1000 v test just in case.

[Derlyn]

Hi Ians

Remember an earth loop impedance test does Not test the impedance of the neutral conductor.

It's actually called a Line Earth Loop Impedance Test. It tests the loop impedance of the Live, Transformer winding and earth.

A high impedance neutral connection cannot be detected by doing the above test.

Derlyn

[GCE]

Hi Ians

We have been caught out twice looking for similar faults in a shower and to make it worse it was intermittent , so we thought.

When the shower doors/panels were installed they managed to get a screw to just touch the live in a piece of twin and earth coming from a light switch . The shower doors would go live at 220v when the bathroom light was switched on .We were there during the day and my guys never thought to switch the lights on.
Because the shower taps and drain etc were connected with pvc piping you only got a tingle and not the full 220v
When I took a earth from the socket in the room next door and tested to the frame work we found the 220v with the light on.
Has happened to me on two separate occasions , years apart.

When the water ran down the frame into the drain and connected with the sewer line it appeared that the voltage was coming from the floor drain which was also pvc

Worth a try using a earth from the sockets close by and switch on all lights , heated towel rails etc