Current flow in main neutral vs. current through water meter
 

On Nov 27, 12:10*pm, "Existential Angst"
wrote:
Awl --

The current in the main neutral *should* be the difference in current
between the main hot legs, right?
However, it is usually off by between 1 and 1.5 amps, which seems to
correspond to the current flow through/around the water meter. *This would
seem to be a *necessary* relationship, right?

My impression is that prior to the utility replacing the old wires along the
poles and to my house, this current flow through/around the water meter was
a lot higher -- 3-5 amps.

So the Q is: *What is "acceptable" ito current flow through the water meter
to the street?

My assumption is that if I took out the water meter, then all of the neutral
current would necessarily flow through the main neutral, and it is just that
apparently the water plumbing ground is "good enough" to share some of the
return load -- which doesn't seem like such a terrible thing, esp. given the
aluminum conductors used by the utility, vs. the copper plumbing to the
street, and perhaps farther.

But again, what are acceptable limits ito of current flow through grounds?
Is there an NEC *ratio, a percentage?
Mine seems to be pretty constant at this 1-1.5 A.

--
EA

My gut reaction is that no freakin' way should you be seeing anything
like an amp going through your water pipes. I'm thinking milliamps
would be cause for investigation.

The aluminum conductors have immeasurably low resistance back to the
utility transformer, unless there's a bad splice or connection
somewhere. The utility company is not going to install service
conductors that have higher resistance than water pipe and damp earth.

Bill may be onto something about current leaking in from nearby
properties, but it would still mean something's wrong (it just may not
be on your property).

How are you measuring this current... clamp-on ammeter? Have you put
this thing around the ground wire that goes to the water pipes? If you
put it around all three of the service conductors (two hots and the
neutral) it ought to read zero. If it does read zero around all three,
but the numbers don't add up when you measure each one separately,
then it's some kind of AC current measurement artifact.

Do you have a ground rod, apart from the connection to the water
pipes?

Chip C
Toronto



Chip C