Service Conductors vs. Service-Entrance Conductors

[Scrubadubbdubb]

I'm working through Understanding the NEC Vol. 1 (2023 Version) and find myself a little confused delineating between service conductors and service-entrance conductors.

Let's say there is a service lateral that ends in a handhole box with the service point located in that handhole box, and then there are conductors from that service point that run directly to and end at the meter terminals. Are these conductors (service-point to meter) considered underground service conductors or service entrance conductors?

Are "Service-Entrance Conductors" considered to be "Service-Conductors" as defined by the NEC. (i.e. Is this a case of all squares are rectangles but not all rectangles are squares?)

Does it matter or am I getting caught up in the weeds? I'm fairly competent in my day-to-day shipboard electrical work but I'm trying make sure I get the foundations of landside installations correct to start with.

Thank you.

 

[Little Bill]

Service Conductors. The conductors from the service point to
the service disconnecting means. (CMP-4)

Service Conductors, Overhead. The overhead conductors
between the service point and the first point of connection to
the service-entrance conductors at the building or other structure.
(CMP-4)

Service Conductors, Underground. The underground conductors
between the service point and the first point of connection
to the service-entrance conductors in a terminal box, meter, or
other enclosure, inside or outside the building wall. (CMP-4)
Informational Note: Where there is no terminal box, meter, or
other enclosure, the point of connection is considered to be the
point of entrance of the service conductors into the building.

Service Drop. The overhead conductors between the utility
electric supply system and the service point. (CMP-4)

Service-Entrance Conductors, Overhead System. The service
conductors between the terminals of the service equipment
and a point usually outside the building, clear of building walls,
where joined by tap or splice to the service drop or overhead
service conductors. (CMP-4)

Service-Entrance Conductors, Underground System. The service
conductors between the terminals of the service equipment
and the point of connection to the service lateral or underground
service conductors. (CMP-4)
Informational Note: Where service equipment is located outside
the building walls, there may be no service-entrance conductors
or they may be entirely outside the building.

Service Equipment. The necessary equipment, usually consisting
of a circuit breaker(s) or switch(es) and fuse(s) and their
accessories, connected to the load end of service conductors to
a building or other structure, or an otherwise designated area,
and intended to constitute the main control and cutoff of the
supply. (CMP-4)

Service Lateral. The underground conductors between the
utility electric supply system and the service point. (CMP-4)
Service Point. The point of connection between the facilities
of the serving utility and the premises wiring.

 

[wwhitney]

Let's say there is a service lateral that ends in a handhole box with the service point located in that handhole box, and then there are conductors from that service point that run directly to and end at the meter terminals. Are these conductors (service-point to meter) considered underground service conductors or service entrance conductors?

I would say it depends on the hand hole box location. If it's right next to the meter, then those would be service entrance conductors. If it's 50' away from the building, those would be service conductors.

Are "Service-Entrance Conductors" considered to be "Service-Conductors" as defined by the NEC. (i.e. Is this a case of all squares are rectangles but not all rectangles are squares?)

Yes, as per the definitions Little Bill kindly posted.

Does it matter or am I getting caught up in the weeds?

It often doesn't matter. Maybe others will have examples where it matters, but only one comes to mind for me. Namely, Service Entrance Conductors are required to be sized using a 125% factor for any continuous portion of the load (unless the service OCPD is 100% rated), while other Service Conductors do not need any 125% continuous use factor.

Cheers, Wayne

 

[electrofelon]

Does it matter or am I getting caught up in the weeds?

Thank you.

I would say the distinction can be significant when you consider 230.40 and it's exceptions. There is a restriction on how many sets of service entrance conductors can be supplied from one service, but no restriction on the number of service conductors. Say for example you had a non dwelling so that 230.40 ex#3 does not apply. Say you had a meter on a pedestal. Now say you want to supply two different buildings. You can indeed supply multiple sets of service conductors, but you would have to arrange the service equipment at each building such that you do not have service entrance conductors (I guess according to the wording, one of the buildings could have service entrance conductors but they could not both have SEC). This could be arranged by having the service disconnect on the outside of the building.

 

[wwhitney]

I would say the distinction can be significant when you consider 230.40 and it's exceptions. There is a restriction on how many sets of service entrance conductors can be supplied from one service, but no restriction on the number of service conductors. Say for example you had a non dwelling so that 230.40 ex#3 does not apply. Say you had a meter on a pedestal. Now say you want to supply two different buildings. You can indeed supply multiple sets of service conductors, but you would have to arrange the service equipment at each building such that you do not have service entrance conductors

That's not how I read 230.40. I would say 230.40 is concerned about multiple sets of service entrance conductors connected at their supply end. Each service lateral or set of underground service conductors can only directly supply one set of service entrance conductors. But if you have one service lateral supplying multiple sets of underground service conductors, I would say each set of underground service conductors can supply one set of service entrance conductors, and that still complies with 230.40 without relying on any exceptions.

Cheers, Wayne

 

[Scrubadubbdubb]

Thank you for posting the definitions concisely like that, referencing them while re-reading my questions and the other answers provided has helped. But I'm still not 100% on this.

Understood, Service-Entrance Conductors are a subset of Service Conductors. Check.

And I think it does matter that I delve into this now as it seems there are indeed times where the distinction is important.

So here's where I'm at.

Service Conductors, Underground. The underground conductors
between the service point and the first point of connection
to the service-entrance conductors in a terminal box, meter, or
other enclosure, inside or outside the building wall. (CMP-4)
Informational Note: Where there is no terminal box, meter, or
other enclosure, the point of connection is considered to be the
point of entrance of the service conductors into the building.


Service-Entrance Conductors, Underground System. The service
conductors between the terminals of the service equipment
and the point of connection to the service lateral or underground
service conductors. (CMP-4)
Informational Note: Where service equipment is located outside
the building walls, there may be no service-entrance conductors
or they may be entirely outside the building.

If I go strictly by the definitions, than it seems the conductors from the handhole box to the meter would be considered Underground Service Conductors whether the handhole box was right near the meter or 50' away. The service entrance conductors in this case would be the conductors on the load side of the meter to the disconnect.

What throws me off about this is that when its a service drop, aren't the conductors that go down the weatherhead and connect to the meter considered Service-Entrance Conductors and not Overhead Service Conductors?

 

[electrofelon]

That's not how I read 230.40. I would say 230.40 is concerned about multiple sets of service entrance conductors connected at their supply end. Each service lateral or set of underground service conductors can only directly supply one set of service entrance conductors. But if you have one service lateral supplying multiple sets of underground service conductors, I would say each set of underground service conductors can supply one set of service entrance conductors, and that still complies with 230.40 without relying on any exceptions.

Cheers, Wayne

An interesting interpretation Wayne. Here is the actual language (from the 2017, not sure if it's still the same):

230.40 Number of Service-Entrance Conductor Sets. Each
service drop, set of overhead service conductors, set of under‐
ground service conductors, or service lateral shall supply only
one set of service-entrance conductors.

So just to clarify, the interpretations are:

1. the list as "all encompassing" that is ifanything on that list appears ahead of your service entrance conductors, that is supplying the service entrance conductors, even if not directly ahead.

2. Only the item on the list that is connected at its load end directly to the service entrance conductors is supplying the service entrance conductors.

You subscribe to #2, and I #1. Correct?

 

[Dennis Alwon]

I'm working through Understanding the NEC Vol. 1 (2023 Version) and find myself a little confused delineating between service conductors and service-entrance conductors.

Let's say there is a service lateral that ends in a handhole box with the service point located in that handhole box, and then there are conductors from that service point that run directly to and end at the meter terminals. Are these conductors (service-point to meter) considered underground service conductors or service entrance conductors?

Are "Service-Entrance Conductors" considered to be "Service-Conductors" as defined by the NEC. (i.e. Is this a case of all squares are rectangles but not all rectangles are squares?)

Does it matter or am I getting caught up in the weeds? I'm fairly competent in my day-to-day shipboard electrical work but I'm trying make sure I get the foundations of landside installations correct to start with.

Thank you.

Personally, I would not get caught up in understanding the difference.

imo, service entrance conductors are considered service conductors so yes it would be a subset so to speak.

Service-Entrance Conductors, Overhead System. The service
conductors between the terminals of the service equipment
and a point usually outside the building, clear of building walls,
where joined by tap or splice to the service drop or overhead
service conductors.

 

[wwhitney]

If I go strictly by the definitions, than it seems the conductors from the handhole box to the meter would be considered Underground Service Conductors whether the handhole box was right near the meter or 50' away. The service entrance conductors in this case would be the conductors on the load side of the meter to the disconnect.

Certainly the conductors between the meter enclosure and the service disconnect enclosure would be service entrance conductors. But for your example:

Service Lateral - Service Point in Handhole -- ?? Conductors -- Meter Enclosure -- SECs -- Service Disconnect

The identity of the ?? Conductors are not determined by the text of the two definitions you quote alone. There are certainly cases where the Service Lateral runs to a POCO Service Termination Box mounted on the building. Then the conductors from it to the meter are definitely SECs. I wouldn't say changing that Service Termination Box to a Handhole next to the foundation, so that a couple feet of those conductors is now underground, changes those conductors from SECs to Underground Service Conductors.

So I guess I'm proposing that it's a balancing test: are the ?? Conductors mostly underground, or mostly installed on the building? First case Underground Service Conductors, second case Service Entrance Conductors.

Cheers, Wayne

 

[wwhitney]

1. the list as "all encompassing" that is ifanything on that list appears ahead of your service entrance conductors, that is supplying the service entrance conductors, even if not directly ahead.

2. Only the item on the list that is connected at its load end directly to the service entrance conductors is supplying the service entrance conductors.

You subscribe to #2, and I #1. Correct?

Yes.

The argument for #2 is that by listing both Service Lateral and Underground Service Conductors, that means that "supply" is limited to "directly supply" rather than "anywhere downstream". As for the latter interpretation of "supply," you'd just list Service Lateral and Service Drop.

Cheers, Wayne

 

[Scrubadubbdubb]

It makes sense to treat it like you say wwhitney, where the percentage underground is more or less the determining factor. I will keep this in mind if I run into times where it will make a difference. Thank you all for taking the time to help me understand this.