400 amp service parallel conductors

[George Stolz]

We can then choose which requirements best serve our interests and ignore others that we interpret to have no bearing. Of course that'll lead to AHJ's doing the same thing!

I have no problem with an AHJ not trying to enforce a sentence in Article 517 when I am wiring a house. If it has no bearing on the installation, then why try to manipulate it into having bearing?

I fail to see the significance of the "minimum" you're adding and removing from the sentence.

• If the service disconnecting means is small enough for 230.79 to artificially inflate it, then .42 makes sense.
• If the service disconnecting means is large enough that .79 is already satisfied, then it follows that the conductors are going to be in accordance with .90(A), and by default are going to be as large or larger than service conductors sized for the minimum size service.

So, what is your point?

 

[Smart $]

I have no problem with an AHJ not trying to enforce a sentence in Article 517 when I am wiring a house. If it has no bearing on the installation, then why try to manipulate it into having bearing?

You're taking my comment beyond it's context. I assume my attempting bring it back into context will be fruitless, so I'm just going to leave it as such.

• If the service disconnecting means is small enough for 230.79 to artificially inflate it, then .42 makes sense.
• If the service disconnecting means is large enough that .79 is already satisfied, then it follows that the conductors are going to be in accordance with .90(A), and by default are going to be as large or larger than service conductors sized for the minimum size service.

Again, this is an interpretation. You will not be able to assimilate my point until you refer only to code text. "In other words" commentary is always an interpretation... and in its best form can be likened to NEC Handbook commentary.

I fail to see the significance of the "minimum" you're adding and removing from the sentence.
...
...
So, what is your point?

Of course you don't see the significance. You are reading 230.42(B) as though the word minimum has already been inserted. That is the point. 230.42(B) says the rating of the service disconnecting means specified in 230.79(A) through (D), which in turn specifies the rating of service disconnecting means shall not be less than a value for the particular type of service. The object of 230.42(B)'s conditional statement is "the rating of the service disconnecting means", not the minimum rating permitted by 230.79 ...and 230.42(B) makes no mention that the rating will be at that specified minimum. It therefore compounds, rather than correlates, the requirement. As it is written, it takes on the following form in math terms:

A_1 ≥ A_2 ≥ A_3​

where

A_1 is the ampacity of the service entrance conductors,
A_2 is the amperage rating of the service disconnecting means, and
A_3 is the minimum amperage rating of the service disconnecting means specified in 230.79(A) through (D).​

Comparatively speaking, you are reading 230.42(B) as:

A_1 ≥ A_3​

 

[suemarkp]

I guess I don't really see your point. 250.42 says "shall not be less than the rating", so that establishes a minimum size for the conductors. 230.79(a) - (d) each say the disconnect shall "have a rating of not less than" and a rating value is then specified. Again, that sounds like a minimum.

Also, look at the title of section 230.42 "Minimum SIze and Rating".

I don't see how adding the word "minimum" to 230.42(B) changes anything as each referred section has the words "not less than" in it.

 

[George Stolz]

I am so not getting your point either.

You will not be able to assimilate my point until you refer only to code text. "In other words" commentary is always an interpretation... and in its best form can be likened to NEC Handbook commentary.

Your first post in the thread was a way off-base interpretation, so don't even give me that.

The gist of 230.42(B) is that if one's service disconnect has a higher amperage rating than the minimum calculated load, the ampacity of the service entrance conductors must have an ampacity equal to or greater than the rating of the service disconnect. Example: calculated load is approximately 325A per ungrounded conductor. One opts for a 400 amp service [disconnect]. The ampacity of the service entrance conductors must be 400A or greater.

You're making this leap from minimum requirements to somehow encompass a service 300A over the minimum, and twisting the words. It's your job to summarize the sentences in a way that makes your case, you can't just wave a magic wand and say the words mean something totally different.

We have a 400 amp service disconnect with a 375A calculated load, and 500 MCM CU service conductors, let's say for a house.

Check for compliance:
230.42(B): Is the ampacity greater than for the service conductors not less than the service disconnecting means specified in 230.79? Check. For a house with a minimum service, #2 AL conductors are required.
230.79: Is the service disconnecting means equal to or larger than the minimum? Check. The minimum for a house is 100A, we're installing a 400A service.
230.90(A): Are the conductors sized for the calculated load, and the OCPD sized accordingly? Check. A single run of 500 MCM CU is rated for 380A, and 230.90(A)x2 allows us to use 240.4(B).

What section are you going to cite to fail this installation?

There's thinking outside the box, and there's wearing a box over your head.
Which are you doing?

 

[Smart $]

I am so not getting your point either.

You've made that quite obvious.

Your first post in the thread was a way off-base interpretation, so don't even give me that.

I'm not interpreting. I'm reading and quoting the written words.

You're making this leap from minimum requirements to somehow encompass a service 300A over the minimum, and twisting the words. It's your job to summarize the sentences in a way that makes your case, you can't just wave a magic wand and say the words mean something totally different.

No leaping or magic wands here. And I'm certainly not twisting the words.

We have a 400 amp service disconnect with a 375A calculated load, and 500 MCM CU service conductors, let's say for a house.

By calculated load, do you mean as specified in 230.42(A)(1) or (2), as appropriate, or do you mean the calculated service load of Article 220 Part III. The results are usually not the same, and we are talking about service entrance conductor ampacity here, you know.

Check for compliance:
230.42(B): Is the ampacity greater than for the service conductors not less than the service disconnecting means specified in 230.79? Check. For a house with a minimum service, #2 AL conductors are required.

The first part of your question makes no sense. And I certainly have no idea how #2 AL conductors enter this picture.

What section are you going to cite to fail this installation?

None. I'm not associated with any AHJ.

There's thinking outside the box, and there's wearing a box over your head.
Which are you doing?

Neither. Comparatively speaking, I'm observing the box.

_______________________________________________________________
Let's try approaching it in the form of a math question:

What condition is placed on X if Y = 400 and the following conditions are satisfied?

Condition 1: X ≥ Y. Condition 2, A through D apply to Y.

Condition 2: Y is conditional upon its color as follows,

A) If Y is black, Y ≥ 15
B) If Y is red, Y ≥ 30
C) If Y is blue, Y ≥ 100
D) For all other colors of Y, Y ≥ 60​

 

[George Stolz]

I'm not interpreting. I'm reading and quoting the written words.

I don't see the words "gist" in that section at all, myself.

The first part of your question makes no sense.

Correction:

Check for compliance:
230.42(B): Is the ampacity for the service conductors not less than required for the service disconnecting means specified in 230.79? Check. For a house with a minimum service, #2 AL conductors are required.

And I certainly have no idea how #2 AL conductors enter this picture.

Ever seen Table 310.15(B)(6), Smart?

Neither. Comparatively speaking, I'm observing the box.

I am Jack's total lack of surprise.

Let's try approaching it in the form of a math question:

Why?

It's written in plain english, you're just trying b.s. you're way out of this, same as always.

 

[Smart $]

I don't see the words "gist" in that section at all, myself.

I was referring only to the part of the discussion with you.

Correction:

Still makes no sense.

Ever seen Table 310.15(B)(6), Smart?

Sure, but we're discussing a specific part or parts of code text, or at least I thought we were. Is there a purpose in adding extraneous, irrelevant, and speculative material?

I am Jack's total lack of surprise.

Lost me here again. Is that some reference to Jack-in-the-Box?

Why?

Why not?

You've attempted to use an example to substantiate your position. Am I not afforded the same privilege?

It's written in plain english, you're just trying b.s. you're way out of this, same as always.

Actually, its written in pseudo-legalese. Nevertheless, I'm sorry to hear you feel that way. I though I pretty much stayed on topic. I guess your sentiments just show how much opinion can vary.

 

[iwire]

Is there a purpose in adding extraneous, irrelevant, and speculative material?

Heck....thats what we all do here, you are one of the best at it.

 

[roger]

Is there a purpose in adding extraneous, irrelevant, and speculative material?

Heck....thats what we all do here, you are one of the best at it.

Roger

 

[George Stolz]

Let's try this another way. This is the NEC text with my interpretation of each part:

230.42(B) Specific Installations.
In addition to the requirements of 230.42(A),
....Also,
the minimum ampacity for ungrounded conductors for specific installations
....the amount of current hots can carry in a service for specific installations...
shall not be less than the rating
....shall not be less than the number...
of the service disconnecting means
....written on the handle of the service disconnecting means...
specified in 230.79(A) through (D).
...of the tiny services listed in 230.79.

How does this section affect a 400A service?

 

[RB1]

Steve,

I don't understand why this is difficult. The language "shall not be less than the rating rating of the service disconnecting means specified in 230.79(A) through (D)" correlates the minmum service entrance conductor size to the minimum rating of the service disconnecting means specified in 230.79. This rule would not apply to service equipment, the rating of which, exceeds the minimum sizes specified in 230.79(A) through (D). 100-amps is the greatest minimum I can find in 230.79(C). I don't think there is a need for any further mathematical analysis of this rule.

 

[Tarzan]

I had no idea this would turn into such a pi$$in match. So lets assume that we have a 208/120 three phase four wire service with a calculated load of 420 amps based on 100% of the non continuous load plus 125% of the continuious load. Does a parallel set of 4/0 copper conductors terminating in a 600 amp service entrance rated, main lug panelboard with four mains and no more than six mains meet the requirments of a 450 amp service.

 

[mpd]

tarzan

any time anybody starts a post with inspector failed me, expect many responses

 

[Smart $]

Let's try this another way. This is the NEC text with my interpretation of each part:

[omitted for brevity]

How does this section affect a 400A service?

It doesn't, by your interpretation.

Now allow me an interpretation. For simplicity, let's use only 230.79(D):

For all other installations, the service disconnecting means shall have a rating of not less than 60 amperes.

We install a 400A service disconnect for a D-type service, knowing this amperage is in excess of the calculated service entrance conductor load. Since the rating meets the requirement of 230.79(D), we can state it as:

For this installation, the service disconnecting means has a rating of 400 amperes.

Now apply 230.42(B) to the immediately preceding quote. How does this affect the ampacity of service entrance conductors?

 

[George Stolz]

Oooooohhhhhh! I get it now!

If I install a 400A service on a building, I need to go to my code book in 230.79(D) and white out the number that's there, and then write in 400! Brilliant!

That's not an interpretation, that's just changing what's written there to make it say something it flat doesn't say.

Why do you not want 230.90(A) to do this job again?

 

[George Stolz]

I had no idea this would turn into such a pi$$in match.

It's a past-time around here. Forgive us for stealing your thread.

So lets assume that we have a 208/120 three phase four wire service with a calculated load of 420 amps based on 100% of the non continuous load plus 125% of the continuious load. Does a parallel set of 4/0 copper conductors terminating in a 600 amp service entrance rated, main lug panelboard with four mains and no more than six mains meet the requirements of a 450 amp service.

Yes, that is compliant. Be sure that the panelboard is rated for use as service equipment in the way you're using it. (Basically, if these handles are all feeders, you're good to go - short story).

 

[Smart $]

Oooooohhhhhh! I get it now!

Oooooohhhhhh! I get it now! You're not only a hypocrite but an exagerating one at that... and to justify that remark, it's really quite simple: You allow yourself to change practically every word of an excerpt to substantiate your position, and I'm not permitted the dignity to change but a few!

This discussion with you ends here!

 

[Smart $]

Heck....thats what we all do here, you are one of the best at it.

Well, gee, Bob. With the uppity persona you project here, having you put me in the same class as you and say I'm one of the best is outright flattering

 

[iwire]

Well, gee, Bob. With the uppity persona you project here, having you put me in the same class as you and say I'm one of the best is outright flattering

I don't deny it, that is why I made "all" bold to indicate I am not above adding extraneous, irrelevant, and speculative material.

It is what we do.

Forget about George for moment, what about the engineers and plan examiner that have responded?

IMO you making the simple complicated.

It's your choice, have fun and play nice.

 

[George Stolz]

Oooooohhhhhh! I get it now! You're not only a hypocrite but an exagerating one at that... and to justify that remark, it's really quite simple: You allow yourself to change practically every word of an excerpt to substantiate your position, and I'm not permitted the dignity to change but a few!

Maybe I'm speaking a foreign language, I don't know.

What I did is called "paraphrasing."

Paraphrasing is defined in the link above:

To paraphrase a statement is to restate it using different words and/or grammar while keeping the same meaning.

The key to paraphrasing is, you can use different words all day along, as long as they mean roughly the same thing when you're finished.

So, looking back at my paraphrase:

the minimum ampacity for ungrounded conductors for specific installations
....the amount of current hots can carry in a service for specific installations...
shall not be less than the rating
....shall not be less than the number...
of the service disconnecting means
....written on the handle of the service disconnecting means...
specified in 230.79(A) through (D).
....of the tiny services listed in 230.79.

Did I alter any of the parts of the section to mean something other than what they meant in the first place?

By contrast, look at what you did:

Now allow me an interpretation. For simplicity, let's use only 230.79(D):

For all other installations, the service disconnecting means shall have a rating of not less than 60 amperes.

We install a 400A service disconnect for a D-type service, knowing this amperage is in excess of the calculated service entrance conductor load. Since the rating meets the requirement of 230.79(D), we can state it as:

For this installation, the service disconnecting means has a rating of 400 amperes.

Now apply 230.42(B) to the immediately preceding quote. How does this affect the ampacity of service entrance conductors?

Don't you see how what you're doing is not valid or logical?

This discussion with you ends here!

Fine by me. I may be hypocritical from time to time, but at least I will admit when I've screwed up.

The only reason I've pursued it this far is because you gave a wrong answer and defended it. My motivation is that people do not walk out of here with wrong answers if I can help it. You can go around believing water's dry as far as I'm concerned, but when it comes to disinforming new members, my hackles get up.