Terminology Question

[charlie b]

I am involved in a project that is experiencing multiple problems with terminology (too many interested parties who are not engineers or electricians). I need to use the right words, or else I will become the cause of confusion. My question is related to a service transformer and a main service switchboard that will both be outdoors, along with all loads. Since nothing "enters" a building, is it still correct to use the phrase, "service entrance conductors" to describe the wires between the transformer and the switchboard?

 

[Eddie702]

Maybe just "Service Conductors" Interesting question and I don't have an answer

 

[david luchini]

I don't think service entrance conductors must "enter" a building. However, I think just "service conductors" would be correct.

Edit: There is an informational note in the definition of "Service-Entrance Conductors, Underground System" that says where service equipment is located outside the building walls, there may be no service-entrance conductors, or they may be entirely outside the building.

I think your case is a "no service-entrance conductors".

 

[don_resqcapt19]

Based on the definition, there are no service entrance conductors where the service lateral or underground service conductors connect directly to the service equipment. The conductors between the transformer and the service equipment are either service lateral conductors or underground service conductors for an underground installation or service drop conductors, or overhead service conductors for an overhead installation. The exact name will change based on them being utility supplied or customer supplied. Service laterals and service drops are utility conductors and the others are customer conductors.

 

[wwhitney]

My question is related to a service transformer and a main service switchboard that will both be outdoors, along with all loads. Since nothing "enters" a building, is it still correct to use the phrase, "service entrance conductors" to describe the wires between the transformer and the switchboard?

That depends on the precise details of the conductor installation between the utility transformer and the service switchboard.

As Don points out, per the Informational Note, if you have unspliced underground conductors running from the utility transformer to the service switchboard terminals, you have no service entrance conductors.

But if you introduce a splice somewhere in there, or if you have an entirely above ground connection between the utility transformer and the service switchboard terminals, then some portion of those conductors are likely service entrance conductors.

Cheers, Wayne

 

[ggunn]

Is there a difference between the way one deals with service conductors vs service entrance conductors?

 

[Tulsa Electrician]

Maybe add a note on the one line Or spell out definition of "service conductors". Conductors between the service transformer and service switch board.

The wires from transformer to main breaker in switch board. Man that would sounds bad coming from an engineer.

 

[wwhitney]

Is there a difference between the way one deals with service conductors vs service entrance conductors?

The primary difference I'm aware of is that service entrance conductors are required to be sized at 125% of the continuous load plus the non-continuous load (when not using a 100% rated OCPD), while service conductors need only be sized to 100% of the load. Only a meaningful difference if taking advantage of 240.4(B) or 230.90(A) Exception 3, which applies when there are 2-6 service disconnects.

Cheers, Wayne

 

[don_resqcapt19]

Is there a difference between the way one deals with service conductors vs service entrance conductors?

The difference in this case would be whose conductors they are. The utility can size them any way they want to, but the customer/contractor must size them in accordance with the rules in the NEC. This would typically result in much larger conductors than what the utility would provide.
Whose conductors they are would be based on where the utility says the service point is.

 

[electrofelon]

Is there a difference between the way one deals with service conductors vs service entrance conductors?

The primary difference I'm aware of is that service entrance conductors are required to be sized at 125% of the continuous load plus the non-continuous load (when not using a 100% rated OCPD), while service conductors need only be sized to 100% of the load. Only a meaningful difference if taking advantage of 240.4(B) or 230.90(A) Exception 3, which applies when there are 2-6 service disconnects.

Cheers, Wayne

Note that 230.40 has the restriction that each service drop or lateral only supply one set of service entrance conductors. Of course there are the famous exceptions as well. This came up a while back and i cant remember if there are situations where you can have more or less restrictions by NOT having service entrance conductors. I am too tired to try to come up with an example (if there is one).

 

[CoolWill]

If I were trying to make it clear to a lay reader, I might call an overhead utility drop to a weather head the "Utility-Owned Supply Conductors" and the conductors after the weather head the "Customer-Owned Supply Conductors". Coming from underground, residential services around me have "Utility-Owned Supply Conductors" because the utility provides the wire. In commercial underground services, the customer usually owns the wire and I would call the portion between the transformer and main the "Customer-Owned Supply Conductors".

 

[charlie b]

I have only a bit role in this project. The project will involve bringing several (noone yet knows how many) "batch plants," rock crushers, and other large equipment to clean up a contaminated beach. Prospective contractors toured the site yesterday.

Some organizations with their own interests are pushing to get power for the equipment designed and installed well before the contract is awarded. I have been tasked with demonstrating that that cannot be done. It's because noone knows how many switchboards will be called for by the successful contractor, nor where they will be placed (it's a large site). Thus, underground ductbanks can't be laid out, and to just guess where to route them would be foolish.

I finished writing my report yesterday. I chose to include (and explain the meaning of) the phrase, "service lateral." Thanks to all for your input.