Maximum # of Disconnects

[bkelly]

Good afternoon, I have an issue I find confusing concerning the maximum number of disconnects for an apartment building. Sorry, I don't have a picture. What I have is a 2 story apartment building with 11 units. There are no fire walls constructed in the building. There is a pad mount transformer with 2 laterals extending from the transformer to the end wall of the building. The 2 laterals terminate into 2 tap boxes side by side with no connection between them. One tap box supplies a 6 meter pack with 6 individual disconnecting means, and the other tap box supplies a 5 meter pack with 5 individual disconnecting means. To me this is 11 movements to disconnect the building power. The engineer cited 230.40, Ex #1, as allowing this. Any thoughts would be appreciated.

 

[Dennis Alwon]

Each service is allowed 6 disconnects. Since you have 2 service laterals then you are allowed 12 disconnects. You see this often on apartments where the service may be on opposite ends of the building. In your case they are together

I agree with the engineer

 

[kwired]

You also have to meet 230.2. I think the only way this can be left is if 230.3(C) gets utilized, otherwise you are generally only allowed one service lateral or one service drop per allowed service. If the supply end of the two laterals originate at same source that is only one service with too many disconnecting means.

For 230.40 exception 1 to come into effect you would need to run service conductors/service disconnecting means to each occupancy not to a common location. Most cases building codes would probably require fire rating between each occupancy as well.

 

[jap]

There is a power company here that will not allow a switch, breaker or disconnecting means between their Xfmr and the line side of the meter bases regardless of how many there are.
Meaning that in a group metering setup there could be 6 or 16 meters, and they will not allow a Main in the tap box as is usually installed in this case.
There has been a few projects where a Main disconnect was included in the tap box for the very reason that there were more than 6 meters and tenant mains but the power company would not hook it up until that main was removed and bypassed.

When I questioned it. It was explained to me this way.

He said if you didn't have the group metering and had to build individual overhead services on the back of a building for say 10 tenants you would have 10 meters 10 disconnects and 10 risers. We would swing (1) overhead service and daisy chain the serviced together at the weatherheads, now, where in that scenario do you see a switch or a disconnect between our transformer bank and the line side of your meterbases ? you don't, and it's not going to happen on an underground service to a group metering setup regardless of the number of meters.

Others see it differently.

JAP>

 

[kwired]

There is a power company here that will not allow a switch, breaker or disconnecting means between their Xfmr and the line side of the meter bases regardless of how many there are.
Meaning that in a group metering setup there could be 6 or 16 meters, and they will not allow a Main in the tap box as is usually installed in this case.
There has been a few projects where a Main disconnect was included in the tap box for the very reason that there were more than 6 meters and tenant mains but the power company would not hook it up until that main was removed and bypassed.

When I questioned it. It was explained to me this way.

He said if you didn't have the group metering and had to build individual overhead services on the back of a building for say 10 tenants you would have 10 meters 10 disconnects and 10 risers. We would swing (1) overhead service and daisy chain the serviced together at the weatherheads, now, where in that scenario do you see a switch or a disconnect between our transformer bank and the line side of your meterbases ? you don't, and it's not going to happen on an underground service to a group metering setup regardless of the number of meters.

Others see it differently.

JAP>

If all 16 are grouped in one location I think it is a NEC violation - too many services/service disconnecting means. But if all 16 are run to each separate occupancy then the exception in 230.40 would apply. JMO

Metering centers with a main section are usually designed so that it is difficult (but not impossible) to steal power from ahead of the meters. If you have a POCO that doesn't accept those then you better have a conversation with both POCO and inspector and have whatever agreement comes from that in writing before being stuck with some gear you can't use.

 

[jap]

If all 16 are grouped in one location I think it is a NEC violation - too many services/service disconnecting means. But if all 16 are run to each separate occupancy then the exception in 230.40 would apply. JMO

Metering centers with a main section are usually designed so that it is difficult (but not impossible) to steal power from ahead of the meters. If you have a POCO that doesn't accept those then you better have a conversation with both POCO and inspector and have whatever agreement comes from that in writing before being stuck with some gear you can't use.

Which is exactly what happened.
The job was bid the same to all of the contractors which was designed on the print with a main for the fact that there were more than 6 movements.
The power company more times than not don't even get to see what the Architects have designed.
The power company would not connect to it until the Main was removed.


JAP>

 

[kwired]

Which is exactly what happened.
The job was bid the same to all of the contractors which was designed on the print with a main for the fact that there were more than 6 movements.
The power company more times than not don't even get to see what the Architects have designed.
The power company would not connect to it until the Main was removed.


JAP>

Designer needs to know what will fly in an area or at least make notes on the plans that state "per power supplier requirements" or something to that effect.

You also have to pass inspection so might want to find out what the inspector may let go.

I still think per NEC it is a violation as the POCO wants it.

 

[jap]

Designer needs to know what will fly in an area or at least make notes on the plans that state "per power supplier requirements" or something to that effect.

You also have to pass inspection so might want to find out what the inspector may let go.

I still think per NEC it is a violation as the POCO wants it.

I'd have to agree with you , but, in this case inspection was passed and ok'd for final hookup and the power company said no and would not connect.

JAP>

 

[kwired]

I'd have to agree with you , but, in this case inspection was passed and ok'd for final hookup and the power company said no and would not connect.

JAP>

What does inspector say if they find out the main disconnect is to be removed?

IMO was NEC compliant, and if you remove the main disconnect it no longer will be.

POCO needs to realize this doesn't meet NEC, and needs to find some compromise on what they will allow. Like I said, most meter centers are arranged so that it is difficult to tap the unmetered conductors even if there is a common main ahead of the meters.

 

[jap]

What does inspector say if they find out the main disconnect is to be removed?

IMO was NEC compliant, and if you remove the main disconnect it no longer will be.

POCO needs to realize this doesn't meet NEC, and needs to find some compromise on what they will allow. Like I said, most meter centers are arranged so that it is difficult to tap the unmetered conductors even if there is a common main ahead of the meters.

I don't think it's as much about the possibility of tapping unmetered conductors to them as much as it is an opening in their conductors before it gets to the line side of the meter base, which they provide the meters for.

They simply have not and will not connect to a group metering that has a main breaker in the tap box as a disconnect.
May be it has something to do with the main being an overcurrent device instead of a NF Disconnect. Not sure, but they won't.

JAP>

 

[kwired]

I don't think it's as much about the possibility of tapping unmetered conductors to them as much as it is an opening in their conductors before it gets to the line side of the meter base, which they provide the meters for.

They simply have not and will not connect to a group metering that has a main breaker in the tap box as a disconnect.
May be it has something to do with the main being an overcurrent device instead of a NF Disconnect. Not sure, but they won't.

JAP>

Having the "opening in their conductors before" the meters should only be a concern when it comes to being able to tap onto them. That is why you need a meter center with only ready access to the main breaker handle, or if fuses are involved you do need to be able to replace fuses. Otherwise everything place that allows easier access to make a tap is usually behind a lockable/seal-able cover, just like the tap box you are otherwise going to end up with will also likely have lock or seal on it's cover.

Is a lot simpler for the fire department or whoever to shut down one to six disconnects then to have to go through sixteen of them in an emergency.

 

[iwire]

Having the "opening in their conductors before" the meters should only be a concern when it comes to being able to tap onto them.

In my opinion what should and should not be a concern for the power companies metering is entirety up to the power company and their oversight agency and not to random people on the Internet.

 

[kwired]

In my opinion what should and should not be a concern for the power companies metering is entirety up to the power company and their oversight agency and not to random people on the Internet.

True, but us installers still have a code to comply with. Now if the POCO installs the meter(s) we have a way around what the POCO is concerned about - but we still have too many service disconnecting means.

 

[don_resqcapt19]

You also have to meet 230.2. I think the only way this can be left is if 230.3(C) gets utilized, otherwise you are generally only allowed one service lateral or one service drop per allowed service. If the supply end of the two laterals originate at same source that is only one service with too many disconnecting means.

For 230.40 exception 1 to come into effect you would need to run service conductors/service disconnecting means to each occupancy not to a common location. Most cases building codes would probably require fire rating between each occupancy as well.

In my opinion that is up to the serving utility and not the NEC. If the utility wants to do it that way, the AHJ is going to be able to change that.

 

[jap]

Having the "opening in their conductors before" the meters should only be a concern when it comes to being able to tap onto them. That is why you need a meter center with only ready access to the main breaker handle, or if fuses are involved you do need to be able to replace fuses. Otherwise everything place that allows easier access to make a tap is usually behind a lockable/seal-able cover, just like the tap box you are otherwise going to end up with will also likely have lock or seal on it's cover.

Is a lot simpler for the fire department or whoever to shut down one to six disconnects then to have to go through sixteen of them in an emergency.

I don't disagree with you.
I'm just saying they will not allow a switch between their transformer and the line side of the meter bases.

Jap>

 

[bkelly]

Thanks for the responses. the utility has always allowed a disconnect before the meters (cold sequence metering). This is just a disagreement between myself as the AHJ and the engineer.