REC Meter Wiring

[Plut]

How do you wire the REC or Generation Meter in a grid tied PV system. I have seen 3 different ways concerning the Ground and Neutral. I have asked both my Inspector and my POCO and they both say do it the way the other wants it.

1. Bond only the Ground and do not connect the Neutral at all. <--The largest POCO in my state requires it this way, However I have a different POCO

2. Bond the Neutral and do not connect Ground at all. <-- A well known online Solar vendor has instructions on their website to wire like this.

3. Bond them both as you would in a regular meter.

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[GreenTeeCrazy]

Hi, I have mine connected as 1st picture.

Passes inspection with no issue.
Solar revenue net meter is grounded but not bonded to neutral.

[Plut]

Thanks for the reply. My plan has been to wire the same way you have it. It seems like the more common sense way to do it. Especially since Neutral is only supposed to be bonded to Ground at the service entrance.

[inetdog]

How do you wire the REC or Generation Meter in a grid tied PV system. I have seen 3 different ways concerning the Ground and Neutral. I have asked both my Inspector and my POCO and they both say do it the way the other wants it.

1. Bond only the Ground and do not connect the Neutral at all. <--The largest POCO in my state requires it this way, However I have a different POCO

2. Bond the Neutral and do not connect Ground at all. <-- A well known online Solar vendor has instructions on their website to wire like this.

3. Bond them both as you would in a regular meter.

This particular question has come up frequently on electrical forums, with no clear consensus on just what the NEC requires, as well as whether or not the NEC applies to a particular installation. The NEC confuses the issue by stating that a PV disconnect for a line side connection does not need to be service rated equipment, but leaving open the question of whether it is a service disconnect just the same.

In your case you are looking at a meter instead, but similar concerns apply.

First of all, a standard residential meter for 120/240V three-wire single phase service does not have a neutral connection (or a ground connection) to the meter itself.
The meter jaws do not provide a neutral connection. There can be a neutral terminal on the meter base which does not connect to the meter, and it will be insulated from the meter enclosure unless a jumper is added to make that connection.

There is a formal demarcation in the system called the service point (or service points) which marks the boundary between POCO wiring, under POCO rules most often directly derived from the NESC (National Electrical Safety Code), and customer wiring, under the jurisdiction of the NEC.
This point is a matter of contract rather than a uniformly defined physical/logical location.
One thing that is certain is that the service point is upstream of the customer's service disconnect switch (which must be associated with overcurrent protection.)
Another is that it is somewhere on the customer side of the utility-owned distribution transformer.

If there is a fused disconnect or breaker upstream of the meter base, then NEC rules and the AHJ (Authority Having Jurisdiction) and its inspectors make the judgements.
If not, then PROBABLY the POCO rules apply and they make the call.

If the NEC rules apply, then the meter base enclosure must be grounded (tied to the building Ground Electrode System or GES, not just an isolated ground rod.)
And depending on how you interpret the NEC rules, that ground must also be bonded, either locally or in adjacent equipment, to the POCO neutral.
Further, if there is a ground-neutral bond in the disconnect switch, there must not be a ground-neutral bond in the meter base unless there is no metallic connection between the two enclosures (e.g. PVC conduit is used and no fourth EGC wire.)
The one thing I would rule out conclusively would be grounding the "neutral" terminal in the meter base and letting the neutral pass through untouched.

Your option #3 is not consistent with NEC requirements IF you also install the neutral-ground bond in the service disconnect in the case of a consumption meter and non-PV installation. It is arguable whether it is consistent with the NEC in the case of a line side PV connection, but again if you do that there should not be a ground-neutral bond in a metallically connected PV disconnect.

If you can get your POCO to tell you where the service point is, you will have the answer on whether POCO or the inspector should be making the decision.

[Sunking]

Plat in any installation the Neutral must be solidly bonded to a Earth Ground at all times. If not you loose th eability for any of your circuit breakers to operate without that bond. It is required to be done at the Service Disconnect point. No if ands or buts.