Utility meter adapter

[cowboyjwc]

So there is a new type of install that I'm seeing here called a UMA (utility meter adapter). It's just what it sounds like, you unplug the meter, plug in the adapter and wire from the load side of the meter to a disconnect, then plug back in the meter.

The first one I saw came off a 100 amp panel with #10 to a disconnect with 100 amp fuses and then #10 to the inverter. I asked why they put in 100 amp fuses and they said that's what the utility required, I told them that they could have just put in a non-fused disconnect as the wires would melt long before the fuses blow.

I keep thinking that this is wrong, but can't really pull anything up, since it even meets the requirements of the feeder tap rule (utility will not allow more than 3' of conductors from the UMA).

Thoughts?

 

[pv_n00b]

There are not a lot of these around. I think SDG&E was the first to use them. http://www.sdge.com/environment/renewable-meter-adapter

These are just another way to do a supply side interconnection, all the usual NEC requirements apply. The ones I have seen have an internal CB in the ring that protects the conductors to the disconnect. Art. 240.21(B)(1)(1)(b) requires that 10' tap conductors to be rated for the OCPD they are landed on so that would be the code violation, assuming you were looking at this as a feeder tap. Not everyone does.

 

[SolarPro]

Vermont's Green Mountain Power was the first utility to adopt this technology:

http://www.greenmountainpower.com/innovative/solar/for-developers-and-installers/

Here is a link to the vendor website:

http://connectder.com/

 

[kwired]

There are not a lot of these around. I think SDG&E was the first to use them. http://www.sdge.com/environment/renewable-meter-adapter

These are just another way to do a supply side interconnection, all the usual NEC requirements apply. The ones I have seen have an internal CB in the ring that protects the conductors to the disconnect. Art. 240.21(B)(1)(1)(b) requires that 10' tap conductors to be rated for the OCPD they are landed on so that would be the code violation, assuming you were looking at this as a feeder tap. Not everyone does.

I don't see why it isn't a feeder tap. There is a circuit breaker inside and looks like it has an operator for external operation of the breaker.

My question is if it is suitable for use as a service disconnecting means? Now comes the issue of all the service disconnecting means for the structure being grouped together, not so much a problem with meter/mains or meter/loadcenter combinations, but some cases you can just plug a breaker into those anyway.

 

[Sierrasparky]

Looks like they need #6

 

[Rampage_Rick]

How does something plugged into the meter socket obtain separate neutral and ground lugs?

 

[kwired]

How does something plugged into the meter socket obtain separate neutral and ground lugs?

I would think it would be considered a service disconnect so incoming would just be one grounded conductor, but you would need a meter socket with a fifth jaw AFAIK, and even then the typical fifth jaw is not all that heavy duty looking as it is usually only intended for very low current for metering equipment.

 

[ggunn]

How does something plugged into the meter socket obtain separate neutral and ground lugs?

In most jurisdictions in Texas it isn't necessary. San Antonio (CPS) is the only one we deal with that considers the line side PV connection to be a service entrance.

I mean this as a an observation only, not as a reignition of the debate. I really don't care one way or the other as long as the AHJ tells us what they want to see so we won't fail inspection.

 

[kwired]

In most jurisdictions in Texas it isn't necessary. San Antonio (CPS) is the only one we deal with that considers the line side PV connection to be a service entrance.

I mean this as a an observation only, not as a reignition of the debate. I really don't care one way or the other as long as the AHJ tells us what they want to see so we won't fail inspection.

But how does one extend the grounded conductor to the equipment being served with a typical 4 jaw single phase meter socket with a plug in module like shown?

 

[jaggedben]

So there is a new type of install that I'm seeing here called a UMA (utility meter adapter). It's just what it sounds like, you unplug the meter, plug in the adapter and wire from the load side of the meter to a disconnect, then plug back in the meter.

The first one I saw came off a 100 amp panel with #10 to a disconnect with 100 amp fuses and then #10 to the inverter. I asked why they put in 100 amp fuses and they said that's what the utility required, I told them that they could have just put in a non-fused disconnect as the wires would melt long before the fuses blow.

I keep thinking that this is wrong, but can't really pull anything up, since it even meets the requirements of the feeder tap rule (utility will not allow more than 3' of conductors from the UMA).

Thoughts?

Stupid of the utility to ask for 100A fuses. Sounds like it should be 6awg between the meter and the fused disconnect, and 30A fuses.

Those mistakes are independent of the adapter being used as a method.

 

[jaggedben]

I don't see why it isn't a feeder tap. ....

Because meter bussing on the supply side is not a feeder. It's part of the service conductors.

 

[jaggedben]

But how does one extend the grounded conductor to the equipment being served with a typical 4 jaw single phase meter socket with a plug in module like shown?

Look at 1:45 of the video. The tech has brought ground and neutral into the service section of the meter/main. Presumably he lands both of them to the neutral somewhere there. Evidently SDG&E thinks there shouldn't be another neutral/ground bond at the solar disconnect. Either that or they are just not overthinking it.

 

[ggunn]

Look at 1:45 of the video. The tech has brought ground and neutral into the service section of the meter/main. Presumably he lands both of them to the neutral somewhere there. Evidently SDG&E thinks there shouldn't be another neutral/ground bond at the solar disconnect.

As we have discussed before, many AHJ's in Texas think that.

 

[K8MHZ]

Look at 1:45 of the video. The tech has brought ground and neutral into the service section of the meter/main. Presumably he lands both of them to the neutral somewhere there. Evidently SDG&E thinks there shouldn't be another neutral/ground bond at the solar disconnect. Either that or they are just not overthinking it.

Just a guess, but maybe the device is such that the only time the PV is delivering power to the house/grid is when there is power from the grid. If the grid loses power, the PV is shut down, so there is no need for a neutral from the PV.

 

[pv_n00b]

If there is some kind of OCPD in the collar the conductor needs to be sized so it can carry the PV current and be protected by the OCPD. It does not matter that the rating of the disconnect switch or fuse might be to this conductor. If there is no OCPD in the collar then the conductor gets sized based on the feeder tap rules and that means sizing it for the fuse rating in the disconnect switch and the PV current. The OP does not say if there is an OCPD in the collar so it's impossible to say if a #10 is acceptable or not. I don't know how many different kinds of these collars there are out there, I've seen two and both have an OCPD in the collar.

 

[jaggedben]

Just a guess, but maybe the device is such that the only time the PV is delivering power to the house/grid is when there is power from the grid. If the grid loses power, the PV is shut down, so there is no need for a neutral from the PV.

You are correct that interactive inverters work this way, but some of them require a neutral. I think you're overthinking the implications of the neutral. This is just a way to do a supply side connection on a meter/main that doesn't have other approved provisions for that.

 

[jaggedben]

If there is some kind of OCPD in the collar the conductor needs to be sized so it can carry the PV current and be protected by the OCPD. It does not matter that the rating of the disconnect switch or fuse might be to this conductor. If there is no OCPD in the collar then the conductor gets sized based on the feeder tap rules and that means sizing it for the fuse rating in the disconnect switch and the PV current. The OP does not say if there is an OCPD in the collar so it's impossible to say if a #10 is acceptable or not. I don't know how many different kinds of these collars there are out there, I've seen two and both have an OCPD in the collar.

Personally I think that if there's no OCPD then the conductors are service entrance conductors. But this has been debated ad nauseum in previous threads, to no conclusion.

 

[iwire]

Personally I think that if there's no OCPD then the conductors are service entrance conductors. But this has been debated ad nauseum in previous threads, to no conclusion.

In other words some people view it differently than you and you cannot understand how that can be.

 

[tkendall1517]

These are being used in AZ for utility owned distributed generation programs. (The utility owns the system and installs it on their customer's roof) We are using the connectder adapter linked above. There is a 60 A opcd in the collar, however we also install a fused disconnect.(The collar opcd is not labeled and it is not obvious if you weren't familiar with the device that there is a breaker in there.) Wire from adapter to disco is #6,fuses in disco are sized to the inverter and wiring to inverter is sized to those fuses. No ground, only L1 L2 and N are run from the disconnect to the adapter. Ground and neutral are bonded in the disconnect, a GEC is run separately from the disconnect to the ground bar in the home's service panel.

Sent from my HTC One A9 using Tapatalk

 

[kwired]

These are being used in AZ for utility owned distributed generation programs. (The utility owns the system and installs it on their customer's roof) We are using the connectder adapter linked above. There is a 60 A opcd in the collar, however we also install a fused disconnect.(The collar opcd is not labeled and it is not obvious if you weren't familiar with the device that there is a breaker in there.) Wire from adapter to disco is #6,fuses in disco are sized to the inverter and wiring to inverter is sized to those fuses. No ground, only L1 L2 and N are run from the disconnect to the adapter. Ground and neutral are bonded in the disconnect, a GEC is run separately from the disconnect to the ground bar in the home's service panel.

Sent from my HTC One A9 using Tapatalk

So NEC isn't being applied to them?