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Spikeyboy 10-13-2010 03:52 PM

voltage on earth wire
 
hi,

last weekend there was a water leak in the house on the main water supply pipe, this pipe is also where the main earth wire for the house is connected. Whilst I was fixing the leak the earth wire became disconnected and at one point I caught it and received a heavy electrical shock. I do have some knowledge of electrics although I am no expert. I started a process of elimination to see if I could find out what was causing the voltage, I disconnected all the appliances in the house and then measured the voltage between the live and earth wires with a multimeter, with everything unplugged there was no voltage reading, when I connected most things there was no change in the voltage but when I connected the washing machine the voltage went to 20v and with the dryer 30v, when I plugged the boiler in it went to 230v

I can only assume from this that there is a problem with the boiler and maybe with the dryer and washing machine, the control unit on the boiler was replaced recently so I am wondering if it wasn't installed correctly, should there be any voltage reading between the live and earth wires under normal circumstances and if so what is an acceptable reading?

Another thing I am not sure about, there is an earth breaker switch installed on the main supply, if there is a leak to earth this should this not trip?

thanks in advance

Spikey

rjniles 10-13-2010 04:14 PM

Based on you terminology, I assume you are not in the US. Are you appliances 120/240 volt or are they pure 220 volt?

The boiler (do you mean a water heater?) has a big problem. It has a phantom connection from a hot line to the chassis of the unit. Do not connect it until the problem is resolved. The washer & dryer may have issues. What type of meter were you using to measure? A digital meter may be reading noise on the cable.

Spikeyboy 10-13-2010 04:23 PM

Quote:

Originally Posted by rjniles (Post 516275)
Based on you terminology, I assume you are not in the US. Are you appliances 120/240 volt or are they pure 220 volt?

The boiler (do you mean a water heater?) has a big problem. It has a phantom connection from a hot line to the chassis of the unit. Do not connect it until the problem is resolved. The washer & dryer may have issues. What type of meter were you using to measure? A digital meter may be reading noise on the cable.

hi, thanks for your response, I am in the Netherlands, the voltage here is 220-230 and all the appliances are for the same voltage

yes sorry I mean a water heater. I will get someone to come and test it. what should I do about the washer and dryer though? they are both less than a year old

the meter was just a regular digital multimeter I bought at a diy store, its not a professional one

also should the earth breaker not trip when there is a voltage leak to earth like this?

Spikey

jbfan 10-13-2010 05:17 PM

We do not have earth breakers in the US, so most of us would not know how they work.
Frenchie will be by here later and he will know and should answer some more questions for you.

Spikeyboy 10-13-2010 05:21 PM

Quote:

Originally Posted by jbfan (Post 516306)
We do not have earth breakers in the US, so most of us would not know how they work.
Frenchie will be by here later and he will know and should answer some more questions for you.

ok thanks, I think they are called ELCB's earth leak circuit breakers, they measure any difference between the live and neutral wires and if there is a measured difference, indicating a leak, they trip cutting off the power supply, hope this helps

Spikey

rjniles 10-13-2010 05:21 PM

Quote:

Originally Posted by Spikeyboy (Post 516279)

the meter was just a regular digital multimeter I bought at a diy store, its not a professional one

also should the earth breaker not trip when there is a voltage leak to earth like this?

Spikey

The breaker may not trip depending on the resistance of the fault.

I assume based on what you said the water heater is a plug in device.

Using the ohms setting on your meter, test from both live terminals of the plug to the metal case of the appliance. The reading should be in the meg-ohms range. If less than 1 meg, the device has a ground fault that needs to be repaired.

AllanJ 10-13-2010 07:11 PM

The 20 volts and 30 volts you measures with the washing machine connected might not be a problem. This may be stray or phantom voltage for a current leakage that is too small to be unsave, a typical digital voltmeter is so sensitive that it picks up this tiny voltage.

Now if you were to connect both a small incandescent light bulb and your meter probes across the wires or terminals or metal parts in question and still get the 20 or 30 volts then you have a leakage problem.

Since you said that some parts were replaced in the water heater or boiler, someone may have made a wrong connection and allowed a hot wire to touch the metal shell or framework of the water heater.

williswires 10-13-2010 07:55 PM

ELCB sounds like what we in the USA know as a ground fault circuit interrupter (GFCI).

By the way...people have DIED from a situation that you describe - becoming a "jumper" for the water pipe in an installation whereby the water pipe is the only grounding electrode on the system. A plumber fixing the water supply pipe or changing the water meter without maintaining the jumper is the most likely scenario.

frenchelectrican 10-13-2010 09:44 PM

Jbfan.,

Thanks for refering to me :thumbsup:.,,

Now let get to the main issue.,

Readers.,,

keep in your mind this part is not a typical North Americian system at all so it may not have direct result to your situation.


Allright now with the ELCB it should work together with RCD breaker but with Netherlands reguations they are little diffrent than what I deal with French regulatons but it will end up simauir anyway.

Did the ELCB breaker was calberated properly ? and also have test to trip function ?? and the earth conductor is good shape if bad shape it may prevent ELCB function properly I know the RCD can work either way.

Willwires ., The ELCB is not the exact as the GFCI fuctionwise but pretty close but the RCD { Resdueal Current Detector } is more closely to GFCI and it function the excat the same but at the diffrent ma setting { our useally either 30 or 100ma depending on which location it being used and yes we do have lower ma rating as well }

As the earth conductor on water pipe the rules are the excat the same as North America is.

Merci.
Marc

williswires 10-13-2010 10:47 PM

Quote:

Originally Posted by frenchelectrican (Post 516454)
Willwires ., The ELCB is not the exact as the GFCI fuctionwise but pretty close but the RCD { Resdueal Current Detector } is more closely to GFCI and it function the excat the same but at the diffrent ma setting { our useally either 30 or 100ma depending on which location it being used and yes we do have lower ma rating as well }

Thanks

Spikeyboy 10-14-2010 05:21 AM

Quote:

Originally Posted by williswires (Post 516375)
ELCB sounds like what we in the USA know as a ground fault circuit interrupter (GFCI).

By the way...people have DIED from a situation that you describe - becoming a "jumper" for the water pipe in an installation whereby the water pipe is the only grounding electrode on the system. A plumber fixing the water supply pipe or changing the water meter without maintaining the jumper is the most likely scenario.

Quote:

Originally Posted by frenchelectrican (Post 516454)
Jbfan.,

Thanks for refering to me :thumbsup:.,,

Now let get to the main issue.,

Readers.,,

keep in your mind this part is not a typical North Americian system at all so it may not have direct result to your situation.


Allright now with the ELCB it should work together with RCD breaker but with Netherlands reguations they are little diffrent than what I deal with French regulatons but it will end up simauir anyway.

Did the ELCB breaker was calberated properly ? and also have test to trip function ?? and the earth conductor is good shape if bad shape it may prevent ELCB function properly I know the RCD can work either way.

Willwires ., The ELCB is not the exact as the GFCI fuctionwise but pretty close but the RCD { Resdueal Current Detector } is more closely to GFCI and it function the excat the same but at the diffrent ma setting { our useally either 30 or 100ma depending on which location it being used and yes we do have lower ma rating as well }

As the earth conductor on water pipe the rules are the excat the same as North America is.

Merci.
Marc


thanks for your replies guys, I know this is a dangerous situation, I could have died, I only found out about this problem because of a water leak on the main pipe, the earth wire became disconnected and I got a 230v shock.

The ELCB has a test trip function, I have tested this and it works ok, I know the unit was replaced earlier this year because we were having problems with it tripping out, as far as I know they only replaced the unit and didn't investigate if there was an underlying problem. I know it is unlikely but could the unit have been wired incorrectly? maybe the incoming power supply was wired to the wrong side of the unit......

I don't think there is an RCD installed, I have no experience with these, I think there is only an ELCB installed. I don't know the condition of the earth conductor on the main water supply on the ground floor, but I know the earth wiring in the apartment itself should be ok, it was installed about 5 years ago, but I think if the earthing wasn't working properly I would get a shock from the water heater chassis every time I touched it right?

The water heater is a wall mounted unit that plugs into a normal wall socket, I took the plug out and measured between the live and earth and neutral and earth on the plug with a multimeter set on ohms, I didn't get any reading, indicating that there is no short circuit which is strange given that it is leaking 230v to earth. Could it be that the leak only occurs when the unit is connected to the power supply? My multimeter only has one ohm setting though, I cannot select between ohms and meg-ohms, I have borrowed a professional meter from work and will test it again tonight

Spikey

frenchelectrican 10-14-2010 08:51 PM

Quote:

Originally Posted by Spikeyboy (Post 516623)
thanks for your replies guys, I know this is a dangerous situation, I could have died, I only found out about this problem because of a water leak on the main pipe, the earth wire became disconnected and I got a 230v shock.

The ELCB has a test trip function, I have tested this and it works ok, I know the unit was replaced earlier this year because we were having problems with it tripping out, as far as I know they only replaced the unit and didn't investigate if there was an underlying problem. I know it is unlikely but could the unit have been wired incorrectly? maybe the incoming power supply was wired to the wrong side of the unit......

Did the Electrician double check the rest of the system ?? that they should done in first place before it get behond of the ELCB set up.

Quote:

I don't think there is an RCD installed, I have no experience with these, I think there is only an ELCB installed. I don't know the condition of the earth conductor on the main water supply on the ground floor, but I know the earth wiring in the apartment itself should be ok, it was installed about 5 years ago, but I think if the earthing wasn't working properly I would get a shock from the water heater chassis every time I touched it right?

The water heater is a wall mounted unit that plugs into a normal wall socket, I took the plug out and measured between the live and earth and neutral and earth on the plug with a multimeter set on ohms, I didn't get any reading, indicating that there is no short circuit which is strange given that it is leaking 230v to earth. Could it be that the leak only occurs when the unit is connected to the power supply? My multimeter only has one ohm setting though, I cannot select between ohms and meg-ohms, I have borrowed a professional meter from work and will test it again tonight

Spikey
As soon I did see the word Apartment my best answer is stop right there and just call the landlord and they will have to call in Electrician to deal with it due the safety regulations.

I know in France our regulations that if have cord / plug attachement with waterheater it must have RCD protection and I think you should have on there as well so let the Electrician sort that one out.

Merci.
Marc

Spikeyboy 10-15-2010 04:06 AM

Quote:

Originally Posted by frenchelectrican (Post 516996)
Did the Electrician double check the rest of the system ?? that they should done in first place before it get behond of the ELCB set up.


As soon I did see the word Apartment my best answer is stop right there and just call the landlord and they will have to call in Electrician to deal with it due the safety regulations.

I know in France our regulations that if have cord / plug attachement with waterheater it must have RCD protection and I think you should have on there as well so let the Electrician sort that one out.

Merci.
Marc


hi Marc, I called the landord about this and an electrician came round, he wasn't very helpful though, he tried telling me it was ok as long as the earth cable didn't come disconnected, I had to insist that he check out the problem and he said someone would come next week, thats why I am trying to find the problem myself. I know that there is only the ELCB unit installed, is this the same as RCD? otherwise I think these are available as plug in units aren't they? I could get one for the plug where the water heater plugs in

thanks

Spikey

frenchelectrican 10-15-2010 12:03 PM

Quote:

Originally Posted by Spikeyboy (Post 517141)
hi Marc, I called the landord about this and an electrician came round, he wasn't very helpful though, he tried telling me it was ok as long as the earth cable didn't come disconnected, I had to insist that he check out the problem and he said someone would come next week, thats why I am trying to find the problem myself. I know that there is only the ELCB unit installed, is this the same as RCD? otherwise I think these are available as plug in units aren't they? I could get one for the plug where the water heater plugs in

thanks

Spikey

Humm ., That is instering to know and Thanks for letting me know what the electrician done so far and sound like that person is not doing very well task on it.

The ELCB and RCD is not the same they are calberated at diffrent setting so with your regulations I know they use the ELCB set up but they should have RCD on your customer unit as well.

The RCD recetpale device., Yes they are on market either in hardwire format or plug in format one of the two and with your set up you should have the RCD on it for your own protection.

Merci.
Marc


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