Meter Socket Grounding

[mobo]

Same reason meters are sealed. To prevent theft of power or in this case, a short between line and load. Keep in mind the POCO have a hundred years or more of providing power and have seen it all. The need to protect the cash register is paramount, so they write the rules. And the NEC does not require a meter.

So more for preventing a short between line/load then, right? Because I can't see how not allowing meter loops prevents theft of power compared to a meter socket on a house. Unless I'm misunderstanding something.

[mobo]

What type of three wire? 480 corner grounded?

480 volt ungrounded.

[tom baker]

My experience with 3 phase 480 delta is limited. I had one that was corner grounded, the fused disconnect had a bus bar in the b phase, with a jumper to ground.
do all the voltages read 480 to ground?

[mobo]

My experience with 3 phase 480 delta is limited. I had one that was corner grounded, the fused disconnect had a bus bar in the b phase, with a jumper to ground.
do all the voltages read 480 to ground?

No, all the voltages are different. And thanks for your replies.

[mobo]

And if someone could educate me...lol....I assume the reason the meter loop would need bonded to the grounded conductor (neutral) is in case of a short which could result in a shock hazard?

[ptonsparky]

And if someone could educate me...lol....I assume the reason the meter loop would need bonded to the grounded conductor (neutral) is in case of a short which could result in a shock hazard?

Yes, a phase to the meter enclosure.

A few months prior to the area POCO mandating separate conduits, I found an up down loop that had one meter line side conductor shorted to the load conductor going back up that loop. We figured it out when the load side of the meter socket was still hot on one side after the meter was pulled. It could have been that way for years. Missed revenue for the POCO plus the safety aspect.

[texie]

480 volt ungrounded.

You want to tread carefully here. Most of these old rural 480 delta services are corner grounded. You need to be certain of what you have and have a full grasp of delta service details.

[texie]

Yes, I meant grounding electrode system.

No, I think you are referring to having a fault return path. All metallic items on the line side of a service disconnect have to be bonded as per 250.92
The grounding electrode system is in addition to this.

[mobo]

Yes, a phase to the meter enclosure.

A few months prior to the area POCO mandating separate conduits, I found an up down loop that had one meter line side conductor shorted to the load conductor going back up that loop. We figured it out when the load side of the meter socket was still hot on one side after the meter was pulled. It could have been that way for years. Missed revenue for the POCO plus the safety aspect.

Wow, interesting. Thanks for that knowledge. Isn't there a fuse that should have blown or something though?

[mobo]

No, I think you are referring to having a fault return path. All metallic items on the line side of a service disconnect have to be bonded as per 250.92
The grounding electrode system is in addition to this.

You are correct, I got the GEC confused with the grounding conductor.

[mobo]

Let me ask this......if you installed a bronze grounding clamp on the aluminum conduit (the up/down meter loop) just below the weatherhead and put a bonding jumper from the clamp to the grounded conductor (neutral), would this be considered approved?

[mobo]

Do you own the meter loop or the POCO?

If you own it, do it over and bring the grounded conductor down in the meter loop. It does not need to go back up.

We can not have the line and load of that meter socket in the same raceway in this area. . The POCO does not supply up/down loops anymore. Only down, so a separate conduit back up for the load.

So how do you do your two separate conduits? One into the hub on top and how with the other conduit?

[ActionDave]

Let me ask this......if you installed a bronze grounding clamp on the aluminum conduit (the up/down meter loop) just below the weatherhead and put a bonding jumper from the clamp to the grounded conductor (neutral), would this be considered approved?

I think it is, but I'd have to look it up and I'm not able to do that right now.

[ActionDave]

So how do you do your two separate conduits? One into the hub on top and how with the other conduit?

LB out the side.

[ptonsparky]

Wow, interesting. Thanks for that knowledge. Isn't there a fuse that should have blown or something though?

Primary fuse on the transformer would have been the only fuse. IIRC the customer had old bare Cu overhead that had slapped together and given grief in previous years blowing the transformer fuse a time or two. The conductors got hot enough to melt the insulation.