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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Can cable from two different services occupy the same troff?

are you sure that there are two actual services, or is it two feeders, or two sets of conductors from the same service?

it is not common to have multiple services, although it is allowed under certain conditions.
 

Hendrix

Senior Member
Location
New England
are you sure that there are two actual services, or is it two feeders, or two sets of conductors from the same service?

it is not common to have multiple services, although it is allowed under certain conditions.

They are two sets of conductors from different services.
 

mgookin

Senior Member
Location
Fort Myers, FL
Absent any code saying it can't be done I'd suggest at least labeling the wireway to reflect that it contains conductors from two different services.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
having multiple services is pretty unusual to begin with, and the few times I have seen it done there was no real advantage to putting the service wires from both in the same wireway. But it is not like my sample size is all that large.
 

mgookin

Senior Member
Location
Fort Myers, FL
having multiple services is pretty unusual to begin with, and the few times I have seen it done there was no real advantage to putting the service wires from both in the same wireway. But it is not like my sample size is all that large.

I thought he was talking about branch circuits from 2 different services.

Multiple services are quite common around here in industrial parks & strip malls because they are built as spec and then a tenant comes along and needs multiple spaces.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I thought he was talking about branch circuits from 2 different services.

Multiple services are quite common around here in industrial parks & strip malls because they are built as spec and then a tenant comes along and needs multiple spaces.

how do they get around the prohibition of multiple services found in the NEC?

I have seen a couple where they brought in redundant services, and at least one where they had a second service that was just for a fire pump. I thought that was really strange, but I gather it was not unusual in that area.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
how do they get around the prohibition of multiple services found in the NEC?
...
In many cases what are called services really are not services...they are multiple sets of service conductors, one set per occupancy, supplied from a common service as permitted by 230.40.

That being said the number of services to a given property is really up to the serving utility. They are not bound by the rules in the NEC and can supply a building with as many services as they want to.
 

jusme123

Senior Member
Location
NY
Occupation
JW
In many cases what are called services really are not services...they are multiple sets of service conductors, one set per occupancy, supplied from a common service as permitted by 230.40.

That being said the number of services to a given property is really up to the serving utility. They are not bound by the rules in the NEC and can supply a building with as many services as they want to.

...and what if 2 separate utilities are involved?
 

kwired

Electron manager
Location
NE Nebraska
If the supply ends of mentioned conductors originate from same source, it is only one service with multiple sets of service conductors.


There are limitations on how many sets of conductors and disconnecting means are permitted to be supplied by one service.

Additional services are permitted for different conditions that require different sources some examples are differences in number of phases, voltage, frequency, capacity needed is larger then what the serving utility will provide through one service.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
...and what if 2 separate utilities are involved?
Like I said in the post you quoted...the number if services is really up to the utility....they are not bound by the rules in the NEC and can supply a building with as many services as they want to.
 

kwired

Electron manager
Location
NE Nebraska
I am not aware of such a rule.
Maybe not the best wording selection on my part. I was trying to give a brief mentioning of what is covered in 230.40.

There is no limit to how many conductors may make up a service, there is limitations on how many service disconnecting means there can be - with some exceptions that allow more in some instances then others. But if as a general rule you are limited to six service disconnecting means per service before any exceptions, then you have no real reason to have more then six parallel conductors sets per allowed service, as you can't supply anything with them.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Maybe not the best wording selection on my part. I was trying to give a brief mentioning of what is covered in 230.40.

There is no limit to how many conductors may make up a service, there is limitations on how many service disconnecting means there can be - with some exceptions that allow more in some instances then others. But if as a general rule you are limited to six service disconnecting means per service before any exceptions, then you have no real reason to have more then six parallel conductors sets per allowed service, as you can't supply anything with them.
I don't agree that is a general rule. The rule is no more than six disconnects per set of service entrance conductors, not per service. Each set of services entrance conductors is permitted to have six means of disconnect, without a limit on the number of sets or service entrance conductors. The only issue that you can't group more than six service disconnects together.
 
I don't agree that is a general rule. The rule is no more than six disconnects per set of service entrance conductors, not per service. Each set of services entrance conductors is permitted to have six means of disconnect, without a limit on the number of sets or service entrance conductors. The only issue that you can't group more than six service disconnects together.

Don would you agree that 230.40 ex 1 is the only way you could have an unlimited number of service entrance conductor sets?

Although i understand the concept if the service point, i have a hard time believing that most ahj's would consider 2 Service drops to different locations one service. Fwiw the handbook diagrams support the "one service drop, one service" idea.
 

kwired

Electron manager
Location
NE Nebraska
Don would you agree that 230.40 ex 1 is the only way you could have an unlimited number of service entrance conductor sets?

Although i understand the concept if the service point, i have a hard time believing that most ahj's would consider 2 Service drops to different locations one service. Fwiw the handbook diagrams support the "one service drop, one service" idea.
You are on board with what I was taught.

2 service drops to two different locations could be looked at as one service - but if supplying the same building it is not a code compliant service unless it meets some of the exceptions - if second drop were supplying a fire pump that would be one of the exceptions.


Exception 1 relates to buildings with more then one occupancy. In most cases those occupancies will have other building code requirements that effectively can make them be seen as separate buildings in some ways anyhow... JMO.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Don would you agree that 230.40 ex 1 is the only way you could have an unlimited number of service entrance conductor sets?
Exactly.
Although i understand the concept if the service point, i have a hard time believing that most ahj's would consider 2 Service drops to different locations one service. Fwiw the handbook diagrams support the "one service drop, one service" idea.
The AHJ has no input on the service point...the utility defines that and they do not have to comply with the NEC. They can have as many service points on a building as they want to. The NEC starts on the load side of the service point.
 
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