I am installing a separate watthour meter in my home to monitor the
power usage of a high load appliance in my garage. The meter is 2
phase 3 wire and is designed w/ the neutral (center pole) bonded to the
housing; there is no way around this, nor have I seen any meters that
make this an option.
I plan to run THHN 4446 wire from my main panel through metal conduit
to the meter housing; the conduit and the meter housing would both be
Thus, when I tie down the neutral to the meter I would have no choice
but to bond it to ground (as the housing is designed).
bonded together in one location: the main service entrance breaker box.
If I am bonding neutral to ground at this second location (my meter
housing), isn't that bad?
What am I supposed to do w/ the ground in a meter housing?
Am I not supposed to bring ground in to the meter housing?
Is it OK to bond ground and neutral in a meter housing?
If not, do I not connect the conduit/housing to the main service
ground, and then just run a separate ground for my garage
It's single phase three wire, not two phase. Typical watt hour meters used
by utility companies bond their neutral to the fifth jaw of the meter, which
is grounded by the utility companies neutral and you don't run a separate
ground to the meter box. If you are trying to sub meter, you may be better
off using something like an "emon demon" designed for that purpose
Sorry, I meant 2 pole (single phase), not 2 phase.
At first I considered getting an emon, but it seemed that a watthour
meter and housing was more professional looking.
I am using an Itron Centron meter.
Do I need a "neutral isolation kit" in order to properly set up a
A neutral isolation kit should be available from the place where you
purchased the meter socket enclosure. If the enclosure is any common
brand name, such as Milbank or Siemens, etc., any electric supply house
should have one.
There is an exception in NEC (2002) Section 250.142(B), Exception #2,
that does permit one to ground meter enclosures on the load side of the
service disconnecting means by connection to the neutral IF all the
meter enclosures are located near the service disconnecting means, plus
some other requirements that don't apply to you.
In other words, you can install the new meter enclosure next to your
existing electric service and feed it off a breaker in the main panel,
then mount a disconnect next to or below the new meter, then run a
conduit to where you need to go from that disconnect. That's how I
would do it anyway.
I must tell you, however, that even though this is permitted by NEC,
some electrical inspectors will not accept it, and will make you
install the neutral isolation kit. You should call your local electric
inspector to see if they will allow it.
Yes bonding the neutral and ground at a second location is bad and it
violates NEC. If you do bond them here you will split the neutral
current across the neutral conductor and the ground conductor. The
ground conductor should not have current on it during normal operation.
You must find a way to isolate them. What exactly are you trying to
I am not sure but I seem to recall that at least some 240V meters do not use
a neutral connection. If not, you could just run the neutral thru the socket
and tie the grounds to the meter base.
On 16 Jan 2007 16:43:20 -0800, email@example.com wrote:
It doesn't sound like you need a neutral at all. I doubt the meter
uses it. The meters I see only have 4 stabs on them, 2 in, 2 out and
only connect to the phase conductors.
If your load is 240v only there doesn't need to be a neutral.
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