Adding a meter between a main panel and subpanel

[Scob]

A customer wants to add individual utilility meters to his two (2) outdoor lighting loads and one subpanel load. The plan is to feed a two gang meter socket from the existing 400A Main, 480V/277V Main panel and then feed from the load side of each meter socket to two (2) new subpanels for the lighting loads and add one meter between the 40A breaker in the Main Panel and the existing subpanel load, all of this wiring can be done under 10 feet. Each existing lighting loads are spread across six (6) 40AMP 3pole 480V breakers, for a grand total of 12, these 12 breakers will be moved to the new lighting subpanels.

My quesitons are: 1. Is a new breaker required in the Main 400A panel to feed the two gang meter socket? or does the 10ft tap rule apply, also can this wiring be sized based on the individual lighting loads or both added together? 2. Do the new lighting subpanels require a main breaker?

 

[paul]

I would look into the E-mon D-mon products sub power monitoring and avoid the meter base setup.

 

[david]

how would you break the neutral bond in a standard meter socket?

 

[kwired]

First thing is in the OP you said "wants to add individual utilility meters"

Do you mean meters provided by and used for billing from the utility? Or do you mean for owners own use for sub metering loads on the premesis? If it is utility company's meters they will likely have some say in how it will be done or they can refuse service if not to their liking.


Second you mentioned all that can be done with under 10 feet of conductor - meaning you are using taps to supply the meter then on to a sub panel.

I was about to say you must have a single overcurrent device at the load end of the tap, but after reading the 10 foot tap rule again I don't know that you have to have a single overcurrent device.

I do know the panel must have overcurrent protection that does not exceed the rating of the panel, so if it is supplied by 400 amp overcurrent device it needs to be a 400 amp panel.

The six breaker rule is for disconnecting services or buildings supplied by a feeder. You are already past the service disconnect as you described it.

 

[Scob]

Yes, these are revenue meters that the Electric Utilitily has recomended to the customer in order to lower his "high" demand fee, i.e. spread the demand across several meters instead of one.

My reading of the 10ft tap rule is, you can tap from a Main Panel using the feed-thru lugs but the Ampacity of the tap conductors must at least greater than 10% of the source OCPD (in this case 400A x .10= 40A) and able to carry the current of the load down stream of the tap, (in this case approximately 300 Amps total for both outdoor fields).

Therefore, can I run a short tap of 350kcmil from the feed-thru lugs of the 400A Main Panel (10' tap rule), to the two gang meter socket, then feed with 3/0 to each new (400A?) subpanel each with a 200A Main Circuit Breaker?

The other single meter would be fed from the existing 40A breaker located in the existing 400A Main Panel and from the meter to the existing subpanel.

 

[david]

Therefore, can I run a short tap of 350kcmil from the feed-thru lugs of the 400A Main Panel (10' tap rule), to the two gang meter socket, then feed with 3/0 to each new (400A?) subpanel each with a 200A Main Circuit Breaker?

No you could not. You would be taping a tap.
Meter sockets generally have a solidly bonded neutral you cannot re-bond the neutral load side of service disconnect how where you planning on handling that.

 

[kwired]

Yes, these are revenue meters that the Electric Utilitily has recomended to the customer in order to lower his "high" demand fee, i.e. spread the demand across several meters instead of one.

My reading of the 10ft tap rule is, you can tap from a Main Panel using the feed-thru lugs but the Ampacity of the tap conductors must at least greater than 10% of the source OCPD (in this case 400A x .10= 40A) and able to carry the current of the load down stream of the tap, (in this case approximately 300 Amps total for both outdoor fields).

Therefore, can I run a short tap of 350kcmil from the feed-thru lugs of the 400A Main Panel (10' tap rule), to the two gang meter socket, then feed with 3/0 to each new (400A?) subpanel each with a 200A Main Circuit Breaker?

The other single meter would be fed from the existing 40A breaker located in the existing 400A Main Panel and from the meter to the existing subpanel.

I find it a little hard to believe that any POCO would suggest this arrangement, let alone allow equipment with customer access on the supply side of the meter(s).

 

[iwire]

let alone allow equipment with customer access on the supply side of the meter(s).

Common here.

I know, you would think they would be more careful but it seems they don't care unless they suspect theft. Once they suspect theft they come by and put locks on everything on the supply side.

 

[kwired]

Common here.

I know, you would think they would be more careful but it seems they don't care unless they suspect theft. Once they suspect theft they come by and put locks on everything on the supply side.

That happens here also with junction boxes, gutters, etc. but not with a panel or fused disconnect on the supply side.

Multi meter centers with a main are designed so there is still access to overcurrent devices but is not necessarily easy to tap into to steal power.

 

[Dennis Alwon]

Maybe I am confused. I understood that there is a 400 amp disconnect after the utility meter. Is this not the case-- then the OP wants to add his own meters. If that is so you need to find a meter base that does not have the neutral bonded to the can.

 

[kwired]

Maybe I am confused. I understood that there is a 400 amp disconnect after the utility meter. Is this not the case-- then the OP wants to add his own meters. If that is so you need to find a meter base that does not have the neutral bonded to the can.

Read post #5 - the meters to be added will be the meters used by POCO for revenue purposes. The original will likely be discontinued. The intent was to lower the demand fees by spreading the demand across multiple meters. My guess is POCO will still come out ahead with minimum charges per meter or higher rate or something. It is still the same demand for them either way.

 

[Cow]

You would be taping a tap.

I do this all the time, usually with brown, orange, and yellow.

 

[Scob]

Ok, I believe I have an answer to my original question, and I too thought that was "taping a tap", so the plan is to install a New 350A breaker in the original 400A lighting panel and feed the two gang meter socket (with removeable Neutrual bonding jumper!) and from each of the load sides of the meter socket to two New 350A lighting panels.

One other question, is a ground rod required on this new meter socket? The utililty engineered mentioned it.

 

[kwired]

Ok, I believe I have an answer to my original question, and I too thought that was "taping a tap", so the plan is to install a New 350A breaker in the original 400A lighting panel and feed the two gang meter socket (with removeable Neutrual bonding jumper!) and from each of the load sides of the meter socket to two New 350A lighting panels.

One other question, is a ground rod required on this new meter socket? The utililty engineered mentioned it.

No additional grounding electrode or grounding electrode conductors need to be installed. You are not installing a new service or separately derived system.