On an 800 amp service where C.T.'s are installed at the POCO's transformer, what size conductor should be used to bond the meter pan? The meter pan states that it is rated for 20 amps. The raceway from the POCO transformer to the meter can only contains #12 conductors. Would a #10 bond suffice?
C.T. Service meter pan bonding
- Thread starter rwinslow
- Start date
- Status
russ
Senior Member
- Location
- Burbank IL
Re: C.T. Service meter pan bonding
I would assume a # 12 would be all thats needed.
Most of the time the meter is on the CT cabinet, but I have seen them remote mounted, and the wire run in 3/4 or 1" pipe. The # 10 should be fine.
This is from my head not from the code book.
I would assume a # 12 would be all thats needed.
Most of the time the meter is on the CT cabinet, but I have seen them remote mounted, and the wire run in 3/4 or 1" pipe. The # 10 should be fine.
This is from my head not from the code book.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: C.T. Service meter pan bonding
The bonding conductor should be at least as large as the largest conductor that can energize it. this case the #12 but Not a bad idea to run the #10. I have been made to bond it like a meter panel but against my opinion.
The bonding conductor should be at least as large as the largest conductor that can energize it. this case the #12 but Not a bad idea to run the #10. I have been made to bond it like a meter panel but against my opinion.
- Location
- Bremerton, Washington
Re: C.T. Service meter pan bonding
Does the POCO have a standard for this? In our area the metering dept does the wiring and bonding. What if you use a grounding lock nut on each of end of the nipple between the two?
[ January 18, 2004, 10:42 PM: Message edited by: tom baker ]
Does the POCO have a standard for this? In our area the metering dept does the wiring and bonding. What if you use a grounding lock nut on each of end of the nipple between the two?
[ January 18, 2004, 10:42 PM: Message edited by: tom baker ]
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: C.T. Service meter pan bonding
I'm not saying that I agree with this logic per se, I'm just bringing up a possible justification.
Perhaps 250.66 ws brought up as per 250.102(C)? Technically, the CT is on the "supply side of Service".
I'm not saying that I agree with this logic per se, I'm just bringing up a possible justification.
charlie
Senior Member
- Location
- Indianapolis
Re: C.T. Service meter pan bonding
IMO, there are two sets of rules to be followed, the rules in the NEC and the rules of the electric utility. The NEC would require that 250.66 be followed and the electric utility would require that their published rules be followed. Even if a new engineer didn't know the rules, another person would and would enforce them.
We require a minimum of #4 Cu be used to ground an enclosure in a similar situation. Regardless, you are required to follow the most restrictive of the two rules.
IMO, there are two sets of rules to be followed, the rules in the NEC and the rules of the electric utility. The NEC would require that 250.66 be followed and the electric utility would require that their published rules be followed. Even if a new engineer didn't know the rules, another person would and would enforce them.
We require a minimum of #4 Cu be used to ground an enclosure in a similar situation. Regardless, you are required to follow the most restrictive of the two rules.
Re: C.T. Service meter pan bonding
Just spoke with a local POCO guy that I know. He said that he has always seen #4 used for bonding in this scenario. Therefore I am going to go with what the POCO is used to seeing. As far as EMT being used, the POCO has not allowed EMT to be used on the service side here since 1999. The only exception being rigid for a mast on overhead service, which is only allowed on an existing service. All new service must be underground. Thanks for the replies.
Just spoke with a local POCO guy that I know. He said that he has always seen #4 used for bonding in this scenario. Therefore I am going to go with what the POCO is used to seeing. As far as EMT being used, the POCO has not allowed EMT to be used on the service side here since 1999. The only exception being rigid for a mast on overhead service, which is only allowed on an existing service. All new service must be underground. Thanks for the replies.
pierre
Senior Member
- Location
- Westchester County, New York
Re: C.T. Service meter pan bonding
One pattern I see here is listening to others who do not back up there comments with code citations, whether NEC or POCO. The Utility has a 'Blue' book that we follow here, it is available online for free to download or view. That is where I would look for the POCO requirements, as their requirements will most likely take precedent here.
Following someone's advice for requirements when they may not be correct generally will not be a problem until a problem develops, then the it hits the fan.
We are dealing with just such an incident now and it is going to cost someone a lot of time (in court) and money to fix it. When all is said and done I will relay the results for any interested.
Pierre
[ January 19, 2004, 11:10 AM: Message edited by: pierre ]
One pattern I see here is listening to others who do not back up there comments with code citations, whether NEC or POCO. The Utility has a 'Blue' book that we follow here, it is available online for free to download or view. That is where I would look for the POCO requirements, as their requirements will most likely take precedent here.
Following someone's advice for requirements when they may not be correct generally will not be a problem until a problem develops, then the it hits the fan.
We are dealing with just such an incident now and it is going to cost someone a lot of time (in court) and money to fix it. When all is said and done I will relay the results for any interested.
Pierre
[ January 19, 2004, 11:10 AM: Message edited by: pierre ]
charlie
Senior Member
- Location
- Indianapolis
russ
Senior Member
- Location
- Burbank IL
Re: C.T. Service meter pan bonding
If the POCO wants the #4 why fight it, I'd still like to see it in black and white.
I've gone through My Commonwealth Edison book and can't find any such requirement. Guess your POCO has different rules. The only thing my Com Ed book keeps repeating is follow local code or NEC.
That would mean using 250.122 (A).
If the POCO wants the #4 why fight it, I'd still like to see it in black and white.
I've gone through My Commonwealth Edison book and can't find any such requirement. Guess your POCO has different rules. The only thing my Com Ed book keeps repeating is follow local code or NEC.
That would mean using 250.122 (A).
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: C.T. Service meter pan bonding
Russ: What code section directs you to 250.122(A)?
pierre
Senior Member
- Location
- Westchester County, New York
Re: C.T. Service meter pan bonding
How about 250.102(C) - with two sets of 500s, that size would be 2/0 copper.
As far as the ten point meterpan, I would think the POCO would require a certain size - which I am willing to think is smaller than 2/0 copper.
Pierre
How about 250.102(C) - with two sets of 500s, that size would be 2/0 copper.
As far as the ten point meterpan, I would think the POCO would require a certain size - which I am willing to think is smaller than 2/0 copper.
Pierre
- Location
- Massachusetts
Re: C.T. Service meter pan bonding
I guess I am lucky here, the POCO requires me to mount the CT meter pan and run an 1 1/4" raceway between it and the CTs.
They pull the wires and provide a bond wire the same size as the CT wires, 12 AWG.
I guess I am lucky here, the POCO requires me to mount the CT meter pan and run an 1 1/4" raceway between it and the CTs.
They pull the wires and provide a bond wire the same size as the CT wires, 12 AWG.
russ
Senior Member
- Location
- Burbank IL
Re: C.T. Service meter pan bonding
Ryan:
I'm just using 250.122s own wording."shall not be required to be larger than the circuit conductors supplying the equipment".
If you tap off of a feed does the ground run with the tap have to be sized to the circuit you tap off of? or the size of the tap wires?
We don't use the NEC here, so I'm just trying to find the right answer like everyone else.
I'm glad I don't really have these problems here, I only have to allow rigid steel or IMC.
Ryan:
I'm just using 250.122s own wording."shall not be required to be larger than the circuit conductors supplying the equipment".
If you tap off of a feed does the ground run with the tap have to be sized to the circuit you tap off of? or the size of the tap wires?
We don't use the NEC here, so I'm just trying to find the right answer like everyone else.
I'm glad I don't really have these problems here, I only have to allow rigid steel or IMC.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: C.T. Service meter pan bonding
Hi Russ. I think its important to realize that the conductor in question is not an equipment grounding conductor, but rather a bonding jumper. That takes you out of 250.122.
As I posted earlier, 250.102(C) discusses bonding on the supply side of the service, which refers you to 250.66.
Hi Russ. I think its important to realize that the conductor in question is not an equipment grounding conductor, but rather a bonding jumper. That takes you out of 250.122.
As I posted earlier, 250.102(C) discusses bonding on the supply side of the service, which refers you to 250.66.
- Location
- Massachusetts
Re: C.T. Service meter pan bonding
It is interesting to note that a meter pan for a CT meter is not one of the items listed in 250.92 requiring bonding.
It is interesting to note that a meter pan for a CT meter is not one of the items listed in 250.92 requiring bonding.
- Status