100/200 meter socket

[WirenutNH]

I haved been asked to upgrade an exisitign duplex service from 2-100 amp meters to a 200/100 meter. The two questions I have are the following:
1) Can the load conductors going to the panel that will not be upgraded pass through the 200 amp side of the new meter socket?
2) If the service is a 200 amp service and you have a 100amp/200amp socket do the service feeders coming from the power company need to be upgraded above 200amps?

 

[growler]

I haved been asked to upgrade an exisitign duplex service from 2-100 amp meters to a 200/100 meter. The two questions I have are the following:
1) Can the load conductors going to the panel that will not be upgraded pass through the 200 amp side of the new meter socket?
2) If the service is a 200 amp service and you have a 100amp/200amp socket do the service feeders coming from the power company need to be upgraded above 200amps?

Ok, just because you have a couple of 100 amp meters doesn't mean that is the service size.

What is the size of the Main overcurrent device ( breaker or fuse ). You can have a 100 amp meter with just a 60 amp main and that's what some of the older duplex have.

If you plan on useing larger main breaker/breakers then you will have to use larger service cable.

Try to be a little more clear about what's existing and what you are going to install and I think you can get answers to your questions.

Around here we often use a dual meter socket with 2 ea. 200 amp meters for a duplex because that's what the power company has in stock. The actual service to each unit may only be 100 amps.

 

[WirenutNH]

The exisiting outside se cable is 2/2 SE, it feeds 2 gang 100 amp sockets, the exisiting mains on the two panles are 100 amp mains. On the owner occupied unit, he has electric range, electric dryer. 30 amp 2 pole feeed going out to a gargse subpanle. The owner would like to add central a/c to his side. With doing this I believe that he would have to upgrade to a 200 amp service. My question is when I upgrade the service can I install 4/0 alum for a 200 amp service of do I have to use a 300 amp rated feeder( 100/200)? I have found a 200/100 rated socket and beileive this will work as it is approved by utility.

Ok, just because you have a couple of 100 amp meters doesn't mean that is the service size.

What is the size of the Main overcurrent device ( breaker or fuse ). You can have a 100 amp meter with just a 60 amp main and that's what some of the older duplex have.

If you plan on useing larger main breaker/breakers then you will have to use larger service cable.

Try to be a little more clear about what's existing and what you are going to install and I think you can get answers to your questions.

Around here we often use a dual meter socket with 2 ea. 200 amp meters for a duplex because that's what the power company has in stock. The actual service to each unit may only be 100 amps.

 

[iwire]

The exisiting outside se cable is 2/2 SE, it feeds 2 gang 100 amp sockets, the exisiting mains on the two panles are 100 amp mains. On the owner occupied unit, he has electric range, electric dryer. 30 amp 2 pole feeed going out to a gargse subpanle. The owner would like to add central a/c to his side. With doing this I believe that he would have to upgrade to a 200 amp service. My question is when I upgrade the service can I install 4/0 alum for a 200 amp service of do I have to use a 300 amp rated feeder( 100/200)? I have found a 200/100 rated socket and beileive this will work as it is approved by utility.

I have no idea what a 200/100 rated socket is.


That aside, when you have more than one service disconnecting means the NEC allows the total rating of the overcurrent protection to exceed the rating of the conductors.

However, you must do a load calculation per article 220 that shows the connected load is less than the rating of the wire.

See 230.90(A) exception 3

Exception No. 3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors.

On the other hand if you have just a single service disconnecting means this would apply.

230.90(A) Ungrounded Conductor. Such protection shall be provided by an overcurrent device in series with each un-grounded service conductor that has a rating or setting not higher than the allowable ampacity of the conductor. A set of fuses shall be considered all the fuses required to protect all the ungrounded conductors of a circuit. Single-pole cir-cuit breakers, grouped in accordance with 230.71(B), shall be considered as one protective device

 

[kwired]

The exisiting outside se cable is 2/2 SE, it feeds 2 gang 100 amp sockets, the exisiting mains on the two panles are 100 amp mains. On the owner occupied unit, he has electric range, electric dryer. 30 amp 2 pole feeed going out to a gargse subpanle. The owner would like to add central a/c to his side. With doing this I believe that he would have to upgrade to a 200 amp service. My question is when I upgrade the service can I install 4/0 alum for a 200 amp service of do I have to use a 300 amp rated feeder( 100/200)? I have found a 200/100 rated socket and beileive this will work as it is approved by utility.

Depends on how you do it an what the load calculation is.

You can have a service conductor supplying two to six disconnecting means that only needs an ampacity equal or greater then the calculated load. But if you have an individual riser or underground feed to each disconnecting means they each need sized to the overcurrent protection devices associated with their respective disconnecting means.

If your load calculation is only 150 amps for both together - you could supply them with a common conductor with only 150 amps ampacity even though the sum of the overcurrent devices is 300 amps and it would be NEC compliant.

Clear as mud?


If changing both meters- I would consider a 200 amp socket for both in most instances - someday the second unit may need upgraded as well. Of course it becomes trickier to size a common feed to them when load is unknown, but maybe use best guesstimate and it may be fine later on. Chances are it will not be any more load on the second unit then what is currently going to be on first so maybe use that figure if allowing for future change to the second unit.

 

[WirenutNH]

Thanks for the point in the right direction