Connecting power monitor to meter only

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
Say I have a stand alone 320 socket on a remote pedestal with no service disconnect. Consider an energy monitoring device which has ct's and a voltage reference. What is the simplest code compliant way to connect this? Please Ignore issues of utility requirements such as equipment connected to or inside the meter socket. It seems 230.82(4) or (5) would be the applicable section. (5) maybe requires a service disconnect? (4) does not seem to. These things usually come with an inline fuse, what is the AIC rating of those anybody know?
 
electrofelon said:
Say I have a stand alone 320 socket on a remote pedestal with no service disconnect. Consider an energy monitoring device which has ct's and a voltage reference. What is the simplest code compliant way to connect this? Please Ignore issues of utility requirements such as equipment connected to or inside the meter socket. It seems 230.82(4) or (5) would be the applicable section. (5) maybe requires a service disconnect? (4) does not seem to. These things usually come with an inline fuse, what is the AIC rating of those anybody know?
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I hook the voltage leads to a breaker on the panel it's feeding and the CT's go around the service conductors. I havent figured out a good lead to connect to the breakers though so I just use a "normal" lead and put it behind the wires in the break and tighten it back down. I know there has to be a better way but I'm just not creative enough to come up with it lol.
 
Krusscher said:
I hook the voltage leads to a breaker on the panel it's feeding and the CT's go around the service conductors. I havent figured out a good lead to connect to the breakers though so I just use a "normal" lead and put it behind the wires in the break and tighten it back down. I know there has to be a better way but I'm just not creative enough to come up with it lol.
Click to expand...
This is a stand alone meter with no panel.
 
230824-1527 EDT

electrofelon:

Specifically what do you want to monitor? For example only the power from the power company, or also other subparts of the system.

Assume you have a single phase center tapped system, and only want to measure power from the power company.. Use clamp-on current transformers. For said single phase system you need two current tranformers, and the less expensive systems use a single voltage measurement, which is either a 120 V source or the total 240 V source. These systems make the assumption that both sides of neutral are essentially equal in voltage.

You can put the current transformers any place that includes the current you are interested in. The voltage measurement needs to come from a useful location near the power source.

.
 
230.82(4) basically lets you connect metering devices 'upstream' of the service disconnect. However I presume you need a metering device that is listed for connection in that location.

If you have a metering device that is listed to be connected upstream of the service disconnect, my guess is that the instructions will describe how to make the connection.

If you have a metering device that is listed to be connected in a panel downstream of the main, then my guess is you would need to provide a panel and have a 'service disconnect' just for the meter.

-Jon
 
gar said:
230824-1527 EDT

electrofelon:

Specifically what do you want to monitor? For example only the power from the power company, or also other subparts of the system.

Assume you have a single phase center tapped system, and only want to measure power from the power company.. Use clamp-on current transformers. For said single phase system you need two current tranformers, and the less expensive systems use a single voltage measurement, which is either a 120 V source or the total 240 V source. These systems make the assumption that both sides of neutral are essentially equal in voltage.

You can put the current transformers any place that includes the current you are interested in. The voltage measurement needs to come from a useful location near the power source.

.
Click to expand...
winnie said:
230.82(4) basically lets you connect metering devices 'upstream' of the service disconnect. However I presume you need a metering device that is listed for connection in that location.

If you have a metering device that is listed to be connected upstream of the service disconnect, my guess is that the instructions will describe how to make the connection.

If you have a metering device that is listed to be connected in a panel downstream of the main, then my guess is you would need to provide a panel and have a 'service disconnect' just for the meter.

-Jon
Click to expand...
Thanks for the replies guys. We have an off the shelf power monitor that has two sets of CT's, one for the house supply and one for the PV system. The question is how to get the voltage taps for the device. If there was distribution equipment at the location, I would just power it from a breaker. 230.82 does not seem to really offer any installation guidance or give any specifics. Do I just put on some ring terminals and connect it to the lugs in the meter socket (or make a tap after the meter socket)? Is that code compliant? It's interesting 230.82(5) seems to say I need to follow the rules for service entrance conductors and have service equipment, while (4) has no such language.
 
My point is that I _bet_ that metering device is listed to be connected to a breaker on a panel, not connected in one of the ways 230.82(4) permits. I don't think 230.82(4) is general permission that you can connect _any_ meter, but rather permission to connect meters listed for that use.

I _think_ what you will need to do is change whatever tap you've used to connect 1 meter to 3 sets of service wires, and make it 4 sets of service wires, to a small distribution panel at the location, and then connect your meter to a breaker on the distribution panel.

However I honestly don't know if my supposition above is correct.

-Jon
 
winnie said:
My point is that I _bet_ that metering device is listed to be connected to a breaker on a panel, not connected in one of the ways 230.82(4) permits. I don't think 230.82(4) is general permission that you can connect _any_ meter, but rather permission to connect meters listed for that use.

I _think_ what you will need to do is change whatever tap you've used to connect 1 meter to 3 sets of service wires, and make it 4 sets of service wires, to a small distribution panel at the location, and then connect your meter to a breaker on the distribution panel.

However I honestly don't know if my supposition above is correct.

-Jon
Click to expand...
I think you are right that it boils down to manufacturer instructions. If they say I can connect right to service conductors, then I am not seeing anything in the code prohibiting that.
 
I agree.

Here is an example of a metering company selling a tap connector specifically for connecting their meters on a service conductor tap.

Not sure about their listing, however.

www.ekmmetering.com

EKM Insulation Piercing Connector

EKM-IPC Insulation Piercing Connector 4/0 wire to 14 AWG wire ~section 2~ Function: Tap a small wire off of a large wire Primary Wire Size: #6 to 4/0 wire Secondary Wire Size: 14 to 10 AWG Model: EKM-IPC A convenient and fast way to safely and securely tap off of an existing line. You can tap...
www.ekmmetering.com www.ekmmetering.com

Jon
 
Krusscher said:
I hook the voltage leads to a breaker on the panel it's feeding and the CT's go around the service conductors. I havent figured out a good lead to connect to the breakers though so I just use a "normal" lead and put it behind the wires in the break and tighten it back down. I know there has to be a better way but I'm just not creative enough to come up with it lol.
Click to expand...
Unless the breaker is listed for two wires, this isn't code compliant as asked.
winnie said:
I agree.

Here is an example of a metering company selling a tap connector specifically for connecting their meters on a service conductor tap.

Not sure about their listing, however.

www.ekmmetering.com

EKM Insulation Piercing Connector

EKM-IPC Insulation Piercing Connector 4/0 wire to 14 AWG wire ~section 2~ Function: Tap a small wire off of a large wire Primary Wire Size: #6 to 4/0 wire Secondary Wire Size: 14 to 10 AWG Model: EKM-IPC A convenient and fast way to safely and securely tap off of an existing line. You can tap...
www.ekmmetering.com www.ekmmetering.com

Jon
Click to expand...
As far as hooking up the voltage side, I go with Winnie. Use the piercing taps he proposed. Make sure you size the wires to 240.21 and terminate in fuses.
 
Krusscher said:
so I just use a "normal" lead and put it behind the wires in the break and tighten it back down.
Click to expand...
Unless the breaker lugs are listed for more than one wire, this is a Code violation. Most breakers big enough to be used as a Main do not have lugs listed for this.

The correct way is to pigtail off of an existing branch breaker or have a branch breaker, feeding nothing but the meter voltage input. If your panel brand is one of those where 15A breakers have lugs rated for 2 wires, you can do it that way. But the voltage input of the meter, despite having almost no actual load, still needs protection for the wires going to it.

As to those piercing connectors, that would be problematic in my opinion:

  • Is this product UL or CSA listed?
    No, this product does not have any such certifications.
Click to expand...
 
Tangent:

I've sometimes wondered how practical it would be to create a metering circuit that works by capacitive coupling through the the insulation of the wires. 'Non contact' voltage detectors and the 'powerback' alarm work on this principal, but I don't know if it would be plausible to get an accurate voltage measurement.

-Jon
 
Jraef said:
Unless the breaker lugs are listed for more than one wire, this is a Code violation. Most breakers big enough to be used as a Main do not have lugs listed for this.

The correct way is to pigtail off of an existing branch breaker or have a branch breaker, feeding nothing but the meter voltage input. If your panel brand is one of those where 15A breakers have lugs rated for 2 wires, you can do it that way. But the voltage input of the meter, despite having almost no actual load, still needs protection for the wires going to it.

As to those piercing connectors, that would be problematic in my opinion:
Click to expand...
Originally I thought he was just using like a logging meter to do a load study. Now I see this is a Permanent install and that would not work lol.
 
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