Something is obviously still connected to the faucet when the power is shut off.

Did the electrician only shut off the breaker feeding the bathroom and not the entire panel?

If only the breaker was shut off, there is another loose wire in the wall touching the faucet that is connected to a separate breaker.

4V isn't likely to be a live electrical circuit problem. What is the nature of the plumbing. Is your water piping properly bonded to the house ground?

I assume that you have actually been shocked by the faucet. You have been 'bit'. That is why you had an electician look at it...

I believe some faucets have been made, with some various battery operated thing-a-ma-jigs... BUT this is NOT what is causing your problem....

What type of Hot Water heater do you have?? Electric??

As Azlighting has suggested - when it is daytime - go on down and shut off the MAIN breaker to your residence. Takes but a moment. Now - ALL power is killed to your home. (If it is not - you have another problem which DOES need to be addressed...)

With MAIN shut off - go check your faucet. Do you read any voltage at it? Have any 'tingle' when you touch it?? If you do, you have another problem...

If you don't know what your MAIN is - just shut off every blessed circuit breaker in your house... That way - you will shut off the MAIN. The MAIN is the one which says, 100; or 125; or 200 - or some such...

With MAIN off - you should not have any electical tingle or voltage at faucet. Now, turn off all other circuits. Turn Main back on... Then, one by one, turn each of the other circuits back on - till the faucet again displays volatage, or you get that 'tingle' when touching...

You have now identified the circuit which has a problem. An electrician should be able to diagnose and FIX this...

As previous mentioned, it is possible (unlikely - but possible) for an electric hot water heater to be having some sort of bad difficulty - and electrically charging the water... (And the way the plumbing runs to this faucet - allows you to get zapped, when you don't notice it with others.) If that's the case - than said unit should be replaced.

And you have copper or galvanized steel for plumbing I take it?? So, hopefully your water pipe is properly grounded?? If you have older wiring, and the piping is grounded, the piping could be providing a return path because of some broken wire...

Hope this helps. It DOES need to be fixed!

I defer to the licensed sparkies, but could a loose neutral be involved, resulting in a ground fault via the piping?

If it continues even with the whole-house breaker OFF, then you have a legit reason to call your POCO, who *should* respond with great concern and enthusiasm, since it is likely their fault, i.e. transformer/mains drop/broken bonding on pole/etc.

It's semi-scary whatever the cause... is it only on this ONE plumbing fixture?

PS: Did the "electrician" who threw up his hands CHARGE you for the 6 hours? =:O

I had a similar problem.
It turned out to be stray voltage.
My electrician could not find the problem. Everything with the house checked out.
I contacted my electric co-op. The tech found a problem in the power line running to all the houses on the street.
I had a thread here about it several years ago but a GW search does not bring it up.

My electrician did not charge me as he did not find the problem. He did fix some unrelated minor problems he found along the way and I paid him for those repairs.

Also, My co-op stated that if when the house power is turned off from the main breaker and you are still getting shocked, it is most likely on a main power line coming into the house.
Hope this helps....

The 4V that you are measuring.....It's 4V between where and where?

Is it between faucet and ground at an outlet, etc.?

KEN

The problem has to be more than 4 volts. You can't feel four volts. Put your fingers across a 6 volt lantern battery and you will see what I mean.

Ours was reading 12 volts. It was just enough to make you pull your hand away.

i had a customer call me up and say his gf was getting a nasty shock when taking a shower, assuming i had done something wrong in the partial re-wire. i tested from the faucet to the tub- 120 volts! i asked the customer to shut off the main breaker- voltage disappeared.

while turning on the breakers 1 by 1, the voltage appeared when the washing machine breaker was turned on. by inspecting under the tub i discovered that he had nicked the black wire only with a very long screw holding the tub down. he had inadvertently hotted the whole tub up with the screw, and i still wonder why no-one died.

another time the problem was shocks coming from the showers. i isolated the problem to be a bad hot water tank element, causing a voltage imbalance in a 3-phase service, coming to the pool change rooms and showers 100 feet away from the main apartment building. the hwt element was causing a different reference point from the neutral, because the break in the element was not exactly 1/2 way down the element.

try another more experienced electrician, this could be a very serious problem. if you have abs pipe on the drain, you may now be getting a proper voltage to ground reading from the faucet to ground.

WATCH YOUR FINGERS! a 120 volt wire + water + you can be a very serious event.

rick