How is the meter itself grounded for ring type meter sockets

[electro486]

Hello quick practical question for you all that have experience installing meters,

For a plug-in type ANSI C12 Form 2S Class 200 meter (typical 200A meter for Form 2S meter sockets in North America) how does the meter itself get grounded? For most meters, I see a horizontal busbar/grounding terminal on the back of the meter at the midline. For ringless meter sockets, I typically see rings (see picture) or terminals around the left and right sides such that the meter's grounding terminal would contact this when inserted. However, for a ring type meter sockets (see example) they don't have these internal grounding rings and the meter's grounding terminal (aka surge relief gap?) looks like it makes contact with the ringed panel (which is painted) rather than any grounding terminal inside the meter socket. ANSI C12.7 does specify that "in sockets of all types, means shall be provided for grounding the surge relief gaps of the watthour meter" so they must have a grounding means, but not sure if that would just be a grounding screw or if the intention is one takes off paint at the appropriate location on the ringed cover or something.

Can anyone shed light on how a Form 2S meter is intended to be grounded when installed in a ring type meter socket?

Thanks for the help!

 

[Little Bill]

Some POCOs allow the GEC in the meter and that is the ground. Those that don't allow it, the meter can gets grounded by the neutral conductor, which should be grounded to the GEC elsewhere. The neutral lug in the meter base is mounted directly to the can in all meter bases.

 

[electro486]

Thanks for the response Little Bill. I'm particularly interested in thoughts re grounding of Form 2S meters which don't have a neutral lug on them (they have 4 main lugs, L1 and L2 on source side and L1 and L2 on load side with neutral being wired through just in the meter socket) so can't be grounded via the neutral. I see many Form 2S meters with an extra ground spade or part horizontally at the midline that contacts the grounding ring on the ringless meter sockets, but in many cases the ring type meter sockets don't appear to have a similar connection available for grounding. I'm wondering if an additional grounding wire or something is added for the ring type cases or if I'm missing something. Thanks

 

[roger]

Can you provide a manufacturer and model number of the meter enclosure you're talking about?

 

[roger]

As far as know they all have a neutral connection as shown below.

 

[roger]

Can you provide a manufacturer and model number of the meter enclosure you're talking about?

Never mind, I looked at you pictures, the neutral connection is factory bonded to the enclosure.

 

[LarryFine]

The OP is asking about grounding the meter itself, not the meter base.

 

[Little Bill]

The OP is asking about grounding the meter itself, not the meter base.

Whaaaat?

 

[LarryFine]

Whaaaat?

For a plug-in type ANSI C12 Form 2S Class 200 meter (typical 200A meter for Form 2S meter sockets in North America) how does the meter itself get grounded? For most meters, I see a horizontal busbar/grounding terminal on the back of the meter at the midline. For ringless meter sockets, I typically see rings (see picture) or terminals around the left and right sides such that the meter's grounding terminal would contact this when inserted. However, for a ring type meter sockets (see example) they don't have these internal grounding rings and the meter's grounding terminal (aka surge relief gap?) looks like it makes contact with the ringed panel (which is painted) rather than any grounding terminal inside the meter socket.

 

[Little Bill]

Never thought about the actual meter needing bonded. Most have a plastic backing, and a glass front.

 

[tom baker]

Same here. Grounding of the meter is the POCOS domain. I install the meter socket per their standards

 

[electro486]

Thanks all, yes I am interested in the grounding of the meter itself. Yes, most meters are primarily plastic and glass, but some do have some exposed metal-typically a band around the middle where the sealing ring connects. Then for install on ring type meter sockets the sealing ring that holds the meter onto the meter socket is almost always metal. So just seems there would be a clear meter grounding practice and means, but maybe I'm just missing something.

 

[Little Bill]

Thanks all, yes I am interested in the grounding of the meter itself. Yes, most meters are primarily plastic and glass, but some do have some exposed metal-typically a band around the middle where the sealing ring connects. Then for install on ring type meter sockets the sealing ring that holds the meter onto the meter socket is almost always metal. So just seems there would be a clear meter grounding practice and means, but maybe I'm just missing something.

The meter is owned by the POCO. Sometimes even the meter base is furnished by the POCO, or usually have a list of acceptable meter bases if we have to source and purchase them.
Any grounding/bonding would be on POCO. I've never even considered anything about that on our end.

 

[hbiss]

Here in Con-Ed territory we use 5 jaw meter cans. The fifth jaw is a ground that we have to connect to the neutral with a short #10 conductor inside the can.

-Hal

 

[ggunn]

The neutral lug in the meter base is mounted directly to the can in all meter bases.

I'm pretty sure not in all of them unless the installers remove the connection in the field for metered and load side interconnected PV systems.

 

[jaggedben]

I'm pretty sure not in all of them unless the installers remove the connection in the field for metered and load side interconnected PV systems.

We just pass the neutral through the can and use the lug that comes bonded to the can for the EGC instead.

But this is not what the OP asked about.

 

[jaggedben]

Thanks all, yes I am interested in the grounding of the meter itself. Yes, most meters are primarily plastic and glass, but some do have some exposed metal-typically a band around the middle where the sealing ring connects. Then for install on ring type meter sockets the sealing ring that holds the meter onto the meter socket is almost always metal. So just seems there would be a clear meter grounding practice and means, but maybe I'm just missing something.

I always wondered why there was a little metal tab sticking out of the utility meters around here, than makes contact with the ring. Maybe it's supposed to ground it. I have no faith that the ring will actually do that. Maybe it's for something else. There is definitely nothing else that would do it but I also don't recall seeing any other exposed metal on the meters around here.

 

[kwired]

I always wondered why there was a little metal tab sticking out of the utility meters around here, than makes contact with the ring. Maybe it's supposed to ground it. I have no faith that the ring will actually do that. Maybe it's for something else. There is definitely nothing else that would do it but I also don't recall seeing any other exposed metal on the meters around here.

Long time ago I had a POCO guy tell me that tab is for ground connection of a surge protector in the meter, and supposedly a reason why that particular POCO wanted a ground rod installed at meter socket locations. I find it hard to believe it makes very good contact, especially with ring style sockets.

This guy told me this back when majority of the meters around were still mechanical meters.

 

[Hv&Lv]

We don’t ground meters

 

[wwhitney]

Basic question: which if any meters require a grounded conductor for voltage reference in order to properly do the metering?

Obviously for currents, it's enough to monitor all but one of the circuit conductors, as the current on the unmonitored conductor will then be determined by the fact the sum of all the currents is zero.

Cheers, Wayne