This is where the water comes into my home. I noticed there is a pipe coming through the wall, then the water meter, then a copper line. The question is, "What is that wire for that's attached to the copper line on one side and the in-line on the other side? It bypasses the meter."

 

It's most likely a ground for your electrical panel if the wire goes toward it from the pipe.
Mike

 

I went down to give it a quick check. Yes, that wire you mention runs from the circuit box to the pipe. But there is this other wire attached to two metal clamps. One clamp is around the pipe on the right side of the meter and the other clamp is on the left side. Hmmm ... It doesn't look like it serves any purpose.

 

Mike is right... this *is* the electrical ground. The reason for the sort jumper across the meter is that electrical code requires this. I'm sure one of the electrical gurus around here can give a better explination, but I believe it is because the meter is not as conductive as the copper pipe (the meter housing is likely brass or iron, which are definately less conductive than copper) so the electrical code (NEC) requires the electrician to jumper from the in-home copper pipes to the copper pipe coming into the house to establish a good earth ground for the electrical system in the house.

jim

 

J.D.,
I'll move this over to the Electrical forum and let the electrical experts there give you an explanation of this type of ground.
Mike

 

The reason for the "jumper" across the meter is so that if at any time the meter is removed for servicing, or if the meter incorporates any resistance to the flow of electrical current, the ground will not be interrupted or inhibited.

 

I wouldnt call myself an expert but this jumper is required because the water meter breaks the continuity of the water pipe before it enters the earth. This jumper ensures that a good ground is maintained between the main panel and the earth. You want the potential to be close to 0 volts. Its all part of the grounding electrode system for your electrical service. This wire from the panel to the meter and then jumping by the meter is specifically called the grounding electode conductor. Also you may or may not have ground rods driven in the ground with a grounding electrode conductor clamped to them.

 

Just a note.
Since the water service is copper coming in from underground this wire IS the grounding electrode conductor. At the same time it is the water bond. The water bond is still required if the water service is plastic, as with a well.
This is to protect the water piping system in the house from becomming energized, or I should say it keeps it from staying energized if a live wire contacts any portion os it. Since it is run to the panel any circuit which may fault to the piping will open the breaker.

Again, the jumper around the meter is; if the wire is connected on the house side you don't lose the grounding electrode if the meter is removed for any reason. Or if it is connected on the street side you don't lose you water bond.

 

The bond is usually there to protect the poor plumber who works on the water meter. It's also there of course to ensure that a continous proper ground is present if the meter is not conductive (rare occurence).

 

The meter looks like solid brass. Is brass a poor electrical conductor? I guess so if a jumper is put in service.

 

Brass is a good conductor. The jumper is because the meter is easily removable.

 

Ah, OK then. The jumper is there if for any reason the meter is removed and let's say for example the circuit box goes haywire or electricity makes contact with the plumbing from any area in the house, the plumber will not receive a nasty electric shock, even if he is grounded, because a human body offers a higher resistance than copper/jumper/copper/earth, and electricity always takes the path of least resistance. Thanks everyone I've actually wanted to know the answer to this for some time now ... just was always distracted by other things.

 

Well not quite.

Electricity takes every path back to the source, not just the easiest or the shortest or the path of least resistance.

Yes, there will be more current on the path with the least resistance, but the other paths will still carry current.

The plumbing is bonded to the electric ground so that if current does find it's way to the plumbing, it will have a ready and available path back to the source.

 

Just a little more refinement of your understanding:

Electricity does _not_ 'take the path of least resistance', implying that it takes that path and no other.

Electricity takes _all_ paths available to it, but in inverse proportion to the resistance of the path.

The various grounding and bonding procedures are all intended to provide very low resistance paths for current flow, so that any human present as a 'parallel path' will only experience infinitesimal current flow, and thus not even feel a shock. But there will be current flow through the human if they become part of the grounding circuit.

Experienced plumbers often carry a set of jumper cables, so that they can bond around any section of pipe that they are removing.

-Jon