NEC service entrance ????????

What he is saying is you have to use 310-16 to size the wire, not the exception for "dwelling services" which takes into account "diversity". We both know you will never use 200a in the shop. Maybe you should just put in a smaller breaker.

BTW it is not going to change in 2005.

Commercial has always been 250AL or 3/0 copper. I doubt any time soon that will change unless it is in the upward change. Just cause the code is in production does not mean that your inspectors will adopt it. Phoenix is still on the 1999. Having code books is not bad thing I have almost every one back to 1987.

Keep the 4/0 and drop the breaker size to 150. If you really need more than that I will be surprised. So will you when you get the bill, especially if there is a demand meter.

I think you are right about not needing more than 150 amp, But the minimum service I can get is 200 so I am stuck with that.

That doesn't mean you need a 200a breaker. Since they started using the "triplex" drops in the 70s everyone gets 200a service most places, take what you need. They only bill you for what you use. We hooked up 100a breakers to 200a services all the time. 100a is the NEC minimum.

Other posts addressed the technical issues, but I thought I would warn you about a more important issue I saw in your post.

NEVER forget that the inspector is the FINAL AUTHORITY! Even if your municipality adopts the new code AND it allows the smaller wire (which I too doubt will happen), your inspector can STILL reject it. You can appeal, then he can stall, then you can complain, and he can stall again, and you can go over his head, and he can appeal etc. etc. etc. Even if (and that is a BIG if) you ultimately prevail, your project could get delayed 1-2 years in the process. Throwing the code book into the face of an inspector is challenging his authority, and it rarely has a favorable outcome.

Fix your attitude and put >Running 3-ph power to my shop behind my house. 200 amp. Mobile, Al.

| Other posts addressed the technical issues, but I thought I would warn | you about a more important issue I saw in your post. | | NEVER forget that the inspector is the FINAL AUTHORITY! | Even if your municipality adopts the new code AND it allows the | smaller wire (which I too doubt will happen), your inspector can STILL | reject it. You can appeal, then he can stall, then you can complain, | and he can stall again, and you can go over his head, and he can | appeal etc. etc. etc. Even if (and that is a BIG if) you ultimately | prevail, your project could get delayed 1-2 years in the process. | Throwing the code book into the face of an inspector is challenging | his authority, and it rarely has a favorable outcome.

Apparently there are some inspectors that need the code book thrown in their face. Kudos to whoever is up to the challenge.

| Fix your attitude and put in a smaller breaker.

But in this case the only issue I would see is classifying the machine shop as commercial. If the OP is going to do any work in there for business purposes, then it's commercial and the inspector could be right. Offhand, I don't know the wire requirements, but this sounds reasonable. And I don't think 2005 changes it. A 150 amp main breaker is cheaper than any other course. That's 150 amp in three phase, too. Mucho juice.

NO. It has nothing to do with "commercial" The table he is trying to use is for "the main power feeder or service to a dwelling". That assumes the normal diversity in a home. As soon as you go to anything but the dwelling "main" you have to use 310.16 If you are really going to do all the things you want to do in your new home with feeders you need to understand this rule.

Maybe where you live inspectors have the effective "final say" but in some places the appeal process is quite speedy and the folks taking the final decision are just "regular" contractors, tradesman, or semi-retired engineers (like myself.) I was on the board of code appeals for about a year. During that time we approved EVERY application for an override of the code and/or inspector. (BTW: I usually was the only one who always "went by the book.")

That said, I would go along with the previous poster and PUT IN A SMALLER BREAKER!

| Maybe where you live inspectors have the effective "final say" but in some | places the appeal process is quite speedy and the folks taking the final | decision are just "regular" contractors, tradesman, or semi-retired | engineers (like myself.) I was on the board of code appeals for about a | year. During that time we approved EVERY application for an override of | the code and/or inspector. (BTW: I usually was the only one who always | "went by the book.")

What were the typical basis for such appeals?

The most common cause was that the code made things so expensive that the project would not make economic sense and the thing would not proceed.

In a case of running too small of a conductor I'm certain that the board would have required that the conductors be protection. We definitely weren't "anything goes."

In one case, a lumber yard put the sprinkler heads ABOVE a screen that was designed to keep birds from nesting among the fixtures, conduits, rafters, etc. The code required them be be below such structures. The owner brought a letter from his insurance company saying that they had no problem.

One case had to to with handicap access in the remodening of a century old building. Another could had to do with electrical and HVAC equipment being below the flood line. In those cases, the board decided that is the owner is willing to take the chance of a flood wiping out his equipment why should we care?

During my term we didn't have a case like that cited. If we had and the owner had a good story like the conduit was in place and in concrete, we would have assured outself that the potential overload was not dangerous. We might even have considered whether everything would be on at the same time for long times or not.

But my point was/is that the inspector just doesn't have the last word. It there is a reasonable appeal process in place the inspector would almost NEVER go beyond the book. He might give some friendly advice but he would not throw his weight about.

Those are all good points. The National Electrical Code (NEC) is a product of the National Fire Protection Association, Inc. (NFPA) and is a guideline toward the safe use of electrical systems and the protection of society from fire hazard. A structure that presents a fire hazard among other structures is a safety consideration. It takes a lot of experience to recognize something that may be a "code violation" but does not present a fire hazard. To approve such a situation, an inspector sometimes goes out on a limb. Most would not consider doing this, and so, the appeals. "Let someone else do the final disposition on this, I've done my job and I'm right considering the code." Of course, an inspector cannot be faulted for this thinking. After all, he is right. And he shouldn't be put out if he is overruled.

Exactly.

That's the enviroment under which we served. The chief of the inspectors was always present at the meetins and he made the initial presentation. The appllicant followed up and the board could ask questions at any time (the board was in charge of the meeting). We met in the office of the chief of the code bureau.

Everyone one was there for the same reason: we wanted the best for the community. Driving up owner costs for no good reason doesn't help anyone and letting a true safety hazzard stay place doesn't help anyone either.

Yes indeed.

I have had a few instances where it was necessary to challenge the inspector, and in one or two the NEC was belatedly changed in my favor!

I don't recall the precise scenario any more, but I had a case with a part-winding start or possibly a wye-delta motor. Motor name plate was 75 amps. Motor had 6 leads, but the phase current was divided between two legs per phase. The code in effect at the time required motor conductor sizes, regardless of their quantity, to be based on nameplate rating, which required conductors much larger than needed.

Inspector disapproved the installation, which was done under engineering supervision. Appealed and won, turns out the inspector didn't know anything about motors and was working to the letter of the law. A version or two later the NEC was changed to permit sizing the motor conductors in wye-delta applications at 58 percent of nameplate.

The system generally works, if slowly.

| Those are all good points. The National Electrical Code (NEC) is a product | of the National Fire Protection Association, Inc. (NFPA) and is a guideline | toward the safe use of electrical systems and the protection of society from | fire hazard. A structure that presents a fire hazard among other structures | is a safety consideration. It takes a lot of experience to recognize | something that may be a "code violation" but does not present a fire hazard. | To approve such a situation, an inspector sometimes goes out on a limb. | Most would not consider doing this, and so, the appeals. "Let someone else | do the final disposition on this, I've done my job and I'm right considering | the code." Of course, an inspector cannot be faulted for this thinking. | After all, he is right. And he shouldn't be put out if he is overruled.

The inspector can basically say "this is technically in violation of the code, but you can get it waived at a panel hearing". Were it me, I'd prefer to see some professional engineer sign off on the technical merits of the waiver. Beyond that, getting it insured is between the owner and the insurer.

That might be a way of encouraging a few more EEs to get the PE ticket. Right now it's hardly worth the yearly dues.

If the inspector 90-4's the installation it IS code. If the insurer wants to sue someone they have to go back to the installer. Inspectors usually have sovereign immunity.

| I don't recall the precise scenario any more, but I had a case with a | part-winding start or possibly a wye-delta motor. Motor name plate was 75 | amps. Motor had 6 leads, but the phase current was divided between two legs | per phase. The code in effect at the time required motor conductor sizes, | regardless of their quantity, to be based on nameplate rating, which | required conductors much larger than needed. | | Inspector disapproved the installation, which was done under engineering | supervision. Appealed and won, turns out the inspector didn't know anything | about motors and was working to the letter of the law. A version or two | later the NEC was changed to permit sizing the motor conductors in wye-delta | applications at 58 percent of nameplate.

Was that 6 windings with a lead per winding (plus everything converging on a neutral) or was it 3 windings with 2 leads per winding? I'm just trying to picture what kind of motor this is. I have a curiosity about motors with 12 or more "magnetic positions" (not knowing whether to describe that as phases, poles, pulses, or windings).

| The system generally works, if slowly.

At least in some jurisdictions.

Pulled out my records; it was a wye-delta application, which would of course mean three independent windings with all six leads brought out, by which means the windings can be connected as either wye or delta. In the US Y-D motors are generally used to implement a form of reduced-voltage starting, and in general are never permanently connected as wye.

Not sure what you mean by "magnetic positions."

A few pointers on motor terminology. A "pole" is a magnetic entity; it is the number of magnetic poles which rotate when the field is energized. A minimum of two poles exist, one N and one S, of course.

Poles are completely separate from phases, which are of course electrical entities. A winding of any number of phases may in general be arranged to give any even number of poles. A single phase motor may have for example 24 poles. A 6 phase motor may have 2 poles. The layout of the windings establishes the relationship between poles and phases.

If you have any OLD motor texts, a good way to visualize this stuff is to look at the layout of an old ring-wound armature. The winding is like a Slinky with the cut ends connected. If you now connect three wires equidistant around the slinky, you will have a two pole three-phase rotor. An applied 3 phase source will generate a two pole revolving field. If you now add jumpers to tie each of the three phases to a point 180 degress away, you will have created a 4 pole armature, which means that it will take 2 rotations of the 3 phases to move a pole 360 degrees.

Adding additional phases adds additional taps to the original plan, adding additional poles adds more of the cross-connects. By this means armatures, or stators, for that matter, of any practical numbers of phases and poles may be built.

Ring-wound armatures have not been used in (literally) 100 years, but I find them excellent tools to explain phases and poles.

| Pulled out my records; it was a wye-delta application, which would of course | mean three independent windings with all six leads brought out, by which | means the windings can be connected as either wye or delta. In the US Y-D | motors are generally used to implement a form of reduced-voltage starting, | and in general are never permanently connected as wye.

So the motor would be wired wye to get started, then switched to delta to run continuously?

| Not sure what you mean by "magnetic positions." | | A few pointers on motor terminology. A "pole" is a magnetic entity; it is | the number of magnetic poles which rotate when the field is energized. A | minimum of two poles exist, one N and one S, of course.

I have seen it referred to where a "pole" means the both ends being counted as one. It's a general ambiguity perhaps caused by incorrect usage of the terminology. I've also seen a couple definitions, but they were sufficiently incomplete to distinguish the inconsistent usages.

| Poles are completely separate from phases, which are of course electrical | entities. A winding of any number of phases may in general be arranged to | give any even number of poles. A single phase motor may have for example 24 | poles. A 6 phase motor may have 2 poles. The layout of the windings | establishes the relationship between poles and phases.

Consider a motor with 12 windings placed at the 12 hour positions of a clock. There are 3 phases. There are 6 of something. And there are 12 of something. Which terminology gets used where?

| If you have any OLD motor texts, a good way to visualize this stuff is to | look at the layout of an old ring-wound armature. The winding is like a | Slinky with the cut ends connected. If you now connect three wires | equidistant around the slinky, you will have a two pole three-phase rotor. | An applied 3 phase source will generate a two pole revolving field. If you | now add jumpers to tie each of the three phases to a point 180 degress away, | you will have created a 4 pole armature, which means that it will take 2 | rotations of the 3 phases to move a pole 360 degrees.

Sorry, I don't have an old motor text, and I can't visualize a slinky as part of a motor construction. I can visualize the slinky loop and the delta connection, but I don't see how it applies to a motor (it seems to be a toroidal inductor).

| Adding additional phases adds additional taps to the original plan, adding | additional poles adds more of the cross-connects. By this means armatures, | or stators, for that matter, of any practical numbers of phases and poles | may be built. | | Ring-wound armatures have not been used in (literally) 100 years, but I find | them excellent tools to explain phases and poles.

Maybe some pictures would help.

I'm visualizing a multi-pole or multi-winding stator with a rotor that is either a squirrel cage, or some number of permanent magnets in some kind of arrangement. The simple construction would be N steel bars with the windings on them, positioned radially from the axis, but far enough out to avoid hitting the rotor. Are these the poles no matter how the windings are configured? Or does the winding configuration matter? I can visualize a few possibilities.

I think there needs to be more than just two terms to over it all.