Private/ Local Unit Metering

8

8sparky8

Member
Location
Columbus, OH
Occupation
Project Manager
I am installing metering on apartment complex's for a company using Grid Gear equipment. It consists of installing the main digital metering box (usually a 2' box with individual digital meters for each unit) and running CT's for each unit as well as a feed from the panel to the metering box. Is there a specific section in the code related to what I am doing?

Asking because the company I am installing it for mentioned that there was a code allowing the meters to be tapped off the main feeders of the panel (so no one can turn off the meter) without needing any sort of overcurrent protection. The metering box's do not contain any OCPD.

First time posting so appreciate any help/ advice/correction.
 
Can you post the particulars of the metering system? Brand, model, etc.

Welcome to the Forum. :)
 
I am not referring to the wiring coming from the CT's which calculate each units power consumption. Each meter box requires 1 circuit just to provide power to the meters and other misc components of the box. It doesn't draw much at all maybe 2-3 amps so we usually just throw a 20amp breaker in the panel and run 12wire to the meter. However the job coming up the meters are in the individual apartments and thus they don't want just a breaker in the panel that the tenant could turn off. Other ones we have done are in the electrical rooms with no tenant access so breakers are fine.

Hopefully that makes sense?
 
8sparky8 said:
I am not referring to the wiring coming from the CT's which calculate each units power consumption. Each meter box requires 1 circuit just to provide power to the meters and other misc components of the box. It doesn't draw much at all maybe 2-3 amps so we usually just throw a 20amp breaker in the panel and run 12wire to the meter. However the job coming up the meters are in the individual apartments and thus they don't want just a breaker in the panel that the tenant could turn off. Other ones we have done are in the electrical rooms with no tenant access so breakers are fine.

Hopefully that makes sense?
Click to expand...
Okay, it does sound like this is the voltage reference wires and they also power the meter itself. In addition to the cts, you also need a voltage reference to measure power. I would provide a small say one amp inline fuse.
 
In my case I wanted them to be listed :D , much less "is that safe?" discussion. Whether the NEC or device instructions require it is another matter, and this is a place where not spending a dollar or so more for the listed holder isn't worth even discussing IMHO.

Looking through back invoices-
MFG : LITTELFUSE INC
Mfg part: 01500332H
DigiKey part: F6775-ND about $2ea quantity 10 (in 2023)
Datasheet: https://www.littelfuse.com/assetdoc...ssetguid=126d0489-0c23-4c79-83d4-547123395b6a

Note that 3AG fuses are not "current-limiting", but with 18g leads and a big enough source, the lead wires will be.
 
zbang said:
In my case I wanted them to be listed :D , much less "is that safe?" discussion. Whether the NEC or device instructions require it is another matter, and this is a place where not spending a dollar or so more for the listed holder isn't worth even discussing IMHO.

Looking through back invoices-
MFG : LITTELFUSE INC
Mfg part: 01500332H
DigiKey part: F6775-ND about $2ea quantity 10 (in 2023)
Datasheet: https://www.littelfuse.com/assetdoc...ssetguid=126d0489-0c23-4c79-83d4-547123395b6a

Note that 3AG fuses are not "current-limiting", but with 18g leads and a big enough source, the lead wires will be.
Click to expand...
I admit I have used the little glass fuses for submeters. Always wonder what the AIC of those things are 😳
 
I appreciate the help. Is there any issue with putting the inline fuses in the panel or would they need to be in the meter box?

Thanks again!
 
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