Service entrance for a commercial building

[shepelec]

An electrician ran an underground service for 760' using 350mcm AL to a
200A meter socket. A second electrician ran 2" pvc from the socket to a
200A mainbreaker panel and installed 4/0 AL.

The load on the service is minimal, if there is a 75A load at this point I would be surprised. But there are plans for future expansion.

I questioned the voltage drop calculation for the 350's but I flagged the 4/0's.
And cited 230.42, 310.15B and 230.90A.

He cited 240.4 B.

These articles seem to contradict each other. Am I missing something?


Paul

 

[infinity]

Voltage drop is not enforceable.
#4/0 AL = 180 amps, next size 200 amps is permitted if load is 180 amps or less. Sounds like contractor is correct.

 

[BryanMD]

An electrician ran an underground service...
A second electrician ran...

Am I missing something?

who did the first guy work for?
and who did the second guy work for?

 

[augie47]

Voltage drop is not enforceable.
#4/0 AL = 180 amps, next size 200 amps is permitted if load is 180 amps or less. Sounds like contractor is correct.

Not that Rob needs my "agree" , but I do agree

 

[iMuse97]

Voltage drop is not enforceable.
#4/0 AL = 180 amps, next size 200 amps is permitted if load is 180 amps or less. Sounds like contractor is correct.

I hear you and agree. However, in this region, voltage drop has been enforced many times.

 

[PetrosA]

I'm not following - why would you need anything larger than 4/0 from the meter to the panel? How long is that run?

 

[shepelec]

Then it appears there are a few useless articles in the code such as
310.15 B 6. Why would there be such an article if it all falls back to 240.4?

Four articles say you can't then one that says you can. It would seem that with all the effort that goes into the NEC, this would have been clarified a long time ago.

I'm not argueing just curious on other interpretations.

I knew that voltage drop was a FPN and did not apply.

 

[hardworkingstiff]

An electrician ran an underground service for 760' using 350mcm AL to a
200A meter socket. A second electrician ran 2" pvc from the socket to a
200A mainbreaker panel and installed 4/0 AL.

The load on the service is minimal, if there is a 75A load at this point I would be surprised. But there are plans for future expansion.

I questioned the voltage drop calculation for the 350's but I flagged the 4/0's.
And cited 230.42, 310.15B and 230.90A.

He cited 240.4 B.

These articles seem to contradict each other. Am I missing something?


Paul

I went and read the articles you listed and thought the following:

230.42: I read it to mean the service-entrance conductors must be capable of handling the calculated load. I didn't see anything else.

310.15 B: These are adjustments factors to the ampacity of conductors, and I didn't see anything in your post to warrant adjustments.

230.90 A: This requires overload protection which you have in the 200-amp main breaker panel.

As others have pointed out (including the contractor) the 4/0 Al. is rated for 180-amps at 75C and since the load (per your post) is well below that, then there is currently no problem as allowed by 240.4 B.

If the construction drawings state the service is being installed for expansion purposes, a conversation with the engineer of record would be in order. If there is not an engineer of record nor an engineered drawing, then I don't believe you have any code violations as I understand your post.

 

[hardworkingstiff]

Then it appears there are a few useless articles in the code such as
310.15 B 6. Why would there be such an article if it all falls back to 240.4?

240.4 only says it your conductors ampacity is greater than the calculated load and does not have an ampacity equal to standard overcurrent rating you may go up to the next size provided you are not above 800-amps.

Four articles say you can't then one that says you can.

You have not posted any articles that say you can't.

It would seem that with all the effort that goes into the NEC, this would have been clarified a long time ago.

Gaining clarification in the NEC takes years. I have learned a lot on this site, these guys are pretty good.

I'm not argueing just curious on other interpretations.

I knew that voltage drop was a FPN and did not apply.

Well a lot of us like to argue. :grin:

 

[shepelec]

In 230.42 I read "Ampacity shall be determined from 310.15".

In 230.90A I read "Such protection shall be provided by an over current device in series with each ungrounded service conductor thas has a rating or setting not higher than the allowable ampacity of the service conductor"

In 310.15B I read "Ampacities for conductors rated 0 to 2000 volts shall be as specified in the Allowable Ampacity Table 310.16 through 310.19 etc"
And 310.15 B 6 seems to back this up.
This is where my question is based. I agree I might be misunderstanding the intent of these articles, but it seems to be clear. I have no problem admitting
I'm wrong, it has happend once or twice before.

As far as the two contractors that is a whole other issue I am working on.

 

[hardworkingstiff]

In 230.42 I read "Ampacity shall be determined from 310.15".

What in 310.15 says you can't use 4/0 AL for a 75-amp load?

In 230.90A I read "Such protection shall be provided by an over current device in series with each ungrounded service conductor thas has a rating or setting not higher than the allowable ampacity of the service conductor"

Section 240.4 allows the 200-amp breaker to protect the 180-amp wire so long as the load is not greater than 180-amps. Your post says it's no greater than 75-amps.

In 310.15B I read "Ampacities for conductors rated 0 to 2000 volts shall be as specified in the Allowable Ampacity Table 310.16 through 310.19 etc"
And 310.15 B 6 seems to back this up.
This is where my question is based. I agree I might be misunderstanding the intent of these articles, but it seems to be clear.

The allowable ampacity of 4/0 AL at 75C is 180-amps. The service load is less than 180-amps. 310.15 B 6 is for Single-phase Dwelling Services, aren't we talking about a commercial service? Besides, 310.15 B 6 allows a 4/0 AL conductor to feed a 200-amp service.

 

[shepelec]

What in 310.15 says you can't use 4/0 AL for a 75-amp load?Section 240.4 allows the 200-amp breaker to protect the 180-amp wire so long as the load is not greater than 180-amps. Your post says it's no greater than 75-amps.The allowable ampacity of 4/0 AL at 75C is 180-amps. The service load is less than 180-amps. 310.15 B 6 is for Single-phase Dwelling Services, aren't we talking about a commercial service? Besides, 310.15 B 6 allows a 4/0 AL conductor to feed a 200-amp service.

310.15 states the ampacity of the wire. The 75A load does not matter.
230.90 states the OC can not be bigger than the ampacity of the wire. Why is exception #5 there?
If none of this matters why do we have 310.15 B 6? It would all fall under 240.4

 

[augie47]

310.15(B)(6) I believe recognizes the fact that in this particular situation the diversity of the load is such that the ampacity rating can be increased.
It is not unlike many Code exceptions which address particular situations
which are variations from the "normal"

 

[electrifier]

If the calculated load is 75 amps, if the calculated load is 145 amps, the 4/0 aluminum conductors are OK but the 200 amp breaker is not necessary. In either case 150 amps or even 175 amps would be the allowable overcurrent protection size. The conductors are large enough for the load which is the first requirement. The overcurrent device must be large enough for the calculated load. The ONLY way for the 200 amp main breaker to be used with 4/0 aluminum conductors in a non residential installation would be if the calculated load exceeds 175 amps and is not larger than 180 amps. A smaller load would necessitate the smaller breaker.

Now for my opinion: This is simply the case where a residential electrician is out of his element and using residential sized wiring for a commercial installation. He was too lazy or cheap to get the proper sized conductors.
The voltage drop issue is just bad design on the part of that electrician. Those of us who care stay within the 3% voltage drop because we care. This guy had 6.5% voltage drop and didn't care. They may try to run some heavier cooking equipment in the future and run into low voltage conditions from the voltage drop. They will then ask why the inspector allowed this to be installed this way. If I was inspecting this I would fail both the contractors for these reasons.

 

[hardworkingstiff]

310.15 states the ampacity of the wire. The 75A load does not matter.

I believe we all agree that the ampacity of 4/0 AL is 180-amps in accordance with 310.15.

230.90 states the OC can not be bigger than the ampacity of the wire. Why is exception #5 there?

If you have a Handbook, read the Application Example on page 164 of the 2008 edition.

The calculated load for a service is 350 amperes. The ampacity of a 500-kcmil, Type XHHW copper conductor is 380 amperes (from Table 310.16), and the conductor is allowed to be protected by a 400-ampere fuse or circuit breaker in accordance with 240.4 (B). The rating of the fuse or circuit breaker is based on the ampacity of the service conductor, not on the rating of the service disconnect switch.

If none of this matters why do we have 310.15 B 6? It would all fall under 240.4

<SIGH> I'm done.

 

[hardworkingstiff]

If the calculated load is 75 amps, if the calculated load is 145 amps, the 4/0 aluminum conductors are OK but the 200 amp breaker is not necessary. In either case 150 amps or even 175 amps would be the allowable overcurrent protection size. The conductors are large enough for the load which is the first requirement. The overcurrent device must be large enough for the calculated load. The ONLY way for the 200 amp main breaker to be used with 4/0 aluminum conductors in a non residential installation would be if the calculated load exceeds 175 amps and is not larger than 180 amps. A smaller load would necessitate the smaller breaker.

All of my training says this is not accurate. It may be a good idea, but I don't believe it to be mandatory.

 

[don_resqcapt19]

310.15 states the ampacity of the wire. The 75A load does not matter.

It does for the application of 240.4(B).

230.90 states the OC can not be bigger than the ampacity of the wire. Why is exception #5 there?

See exception #2 to 230.90(A). This applies to all services in general. It only permits the larger OCPD when the load does not exceed the T310.16 ampacity of the conductor. Exception #5 along with T310.15(B)(6) permits the use of smaller conductors even when the load exceeds the T310.16 ampacity of the conductor.

 

[augie47]

If the calculated load is 75 amps, if the calculated load is 145 amps, the 4/0 aluminum conductors are OK but the 200 amp breaker is not necessary. In either case 150 amps or even 175 amps would be the allowable overcurrent protection size. The conductors are large enough for the load which is the first requirement. The overcurrent device must be large enough for the calculated load. The ONLY way for the 200 amp main breaker to be used with 4/0 aluminum conductors in a non residential installation would be if the calculated load exceeds 175 amps and is not larger than 180 amps. A smaller load would necessitate the smaller breaker.

.

Can you give me a Code reference on this "requirement" ?

 

[benaround]

If the calculated load is 75 amps, if the calculated load is 145 amps, the 4/0 aluminum conductors are OK but the 200 amp breaker is not necessary. In either case 150 amps or even 175 amps would be the allowable overcurrent protection size. The conductors are large enough for the load which is the first requirement. The overcurrent device must be large enough for the calculated load. The ONLY way for the 200 amp main breaker to be used with 4/0 aluminum conductors in a non residential installation would be if the calculated load exceeds 175 amps and is not larger than 180 amps. A smaller load would necessitate the smaller breaker.

Now for my opinion: This is simply the case where a residential electrician is out of his element and using residential sized wiring for a commercial installation. He was too lazy or cheap to get the proper sized conductors.
The voltage drop issue is just bad design on the part of that electrician. Those of us who care stay within the 3% voltage drop because we care. This guy had 6.5% voltage drop and didn't care. They may try to run some heavier cooking equipment in the future and run into low voltage conditions from the voltage drop. They will then ask why the inspector allowed this to be installed this way. If I was inspecting this I would fail both the contractors for these reasons.

You can't inspect for what may happen in the future, you can only inspect for what is

installed. This is explained in 90.1 (B), for your sake as an Inspector, you should under-

stand this Article. Don't take this the wrong way.