1-Voltage, 2-Wire Secondary

[david luchini]

Not true. The 2014 Handbook has explicit author's commentary following 240.4(F) that explicitly refers to these circumstances as "special cases."

Am I taking a little bit of creative freedom in going from "special case" to "rare exception?" Yes, but that is hardly a stretch.

So what I said was true, then.

 

[Jerramundi]

So what I said was true, then.

Explicitly and in regards to it being enforceable - Yes.
Implicitly and logically, no.

 

[david luchini]

yes.

So that's a yes then. It seems to me that if you have to add words that aren't in the Code to support a specific interpretation, that interpretation is probably wrong.

 

[Jerramundi]

So that's a yes then. It seems to me that if you have to add words that aren't in the Code to support a specific interpretation, that interpretation is probably wrong.

Meh. Agree to disagree then. I think the Handbook Notes serve a legitimate purpose - to give us perspective on the actual code.

 

[david luchini]

Meh. Agree to disagree then. I think the Handbook Notes serve a legitimate purpose - to give us perspective on the actual code.

And the note doesn't say anything about "Rare Exception." It mentions two "special cases" and tells you what the two "special cases" are.

The two "special cases" that just happen to be mentioned right in the text of 240.4(F).

 

[Jerramundi]

And the note doesn't say anything about "Rare Exception." It mentions two "special cases" and tells you what the two "special cases" are.

The two "special cases" that just happen to be mentioned right in the text of 240.4(F).

I already acknowledged that I was taking some creative freedom in going from "special case" to "rare exception." But I stand by my comments that...

(1) the two phrases are not far apart by any means and have the same implied meaning of rarity.

(2) one could reasonably conclude that wiring any multiple coil, multiple output xfmr for a "2-wire (single votlage) secondary" per its' nameplate is a plausible contradiction to said "rarity."

(3) the handbook notes, while not technically enforceable, serve a legitimate purpose to offer some perspective on the technical language of the NEC.

 

[wwhitney]

A bit of a side track, but I would say special case does not imply rarity. It just means for a particular value of some parameters that could vary widely. It might be that those particular values are in fact the most likely values, it's still a special case as far as the analysis goes.

Cheers, Wayne

 

[Jerramundi]

A bit of a side track, but I would say special case does not imply rarity. It just means for a particular value of some parameters that could vary widely. It might be that those particular values are in fact the most likely values, it's still a special case as far as the analysis goes.

Cheers, Wayne

Not a "side track." Completely relevant. You're just arguing a different interpretation of the meaning of "special case," but I'm sorry I cannot agree that said phrase (i.e. "special case") does not imply rarity.

 

[LarryFine]

It seems to me that if you have to add words that aren't in the Code to support a specific interpretation, that interpretation is probably wrong.

That's why I see it the way I do. It says what it says. Other members are saying "but, it also means this . . . "

 

[Jerramundi]

A bit of a side track, but I would say special case does not imply rarity. It just means for a particular value of some parameters that could vary widely. It might be that those particular values are in fact the most likely values, it's still a special case as far as the analysis goes.

Cheers, Wayne

I suppose the word "Special" could mean "Particularity" as opposed to "Rarity" per the definition of "Special" in Merriam-Webster...

... but there are other definitions of the word "Special," mainly the FIRST entry in Merriam-Webster under "Special," that utilize the word "Unusual" which is explicitly defined as "Uncommon, Rare."

 

[david luchini]

The commentary literally tells you what the two "special cases" are, and they are literally the same as the text of the Code.

The concept of "rarity" is in neither the Code nor the commentary. You are adding that.

 

[david luchini]

That's why I see it the way I do. It says what it says. Other members are saying "but, it also means this . . . "

Isn't that what you are doing? Aren't you adding "as manufactured"?

 

[Jerramundi]

I'm not arguing a different interpretation a "special case." The commentary literally tells you what the two "special cases" are, and they are literally the same as the text of the Code.

The concept of "rarity" is in neither the Code nor the commentary. You are adding that.

Disagree in part.

Every single word in the code is meaningless without an explicit definition, of which we must defer to the dictionary if not defined in Article 100... and the word "Special" is defined in said text as meaning "Unusual," which is explicitly defined as "Rare, Uncommon."

I will acknowledge that another acceptable definition of "Special" is "Particularity" as opposed "Rarity," conceeding, in part, to your arguments.

But I will NOT acknowledge that I've out right invented some irrelevant interpretation of the word "Special."

 

[david luchini]

Disagree in part.

Every single word in the code is meaningless without an explicit definition, of which we must defer to the dictionary if not defined in Article 100... and the word "Special" is defined in said text as meaning "Unusual," which is explicitly defined as "Rare, Uncommon."

I will acknowledge that another acceptable definition of "Special" is "Particularity" as opposed "Rarity," conceeding, in part, to your arguments.

But I will NOT acknowledge that I've out right invented some irrelevant interpretation of the word "Special."

Special is also defined as Readily distinguishable from others of the same category. As in this case, where the rules for secondary conductor protection for 2 wire, and 3 wire delta transformers are distinguishable from the rules for secondary conductor protection for other transformers.

"Rarity" is not relevant to the secondary conductor protection rules.

 

[LarryFine]

Isn't that what you are doing? Aren't you adding "as manufactured"?

Not really. I'm merely saying that a dual-voltage, four-wire secondary does not magically become a "single voltage, two wire secondary" because of how the four wires are connected.

 

[wwhitney]

Not really. I'm merely saying that a dual-voltage, four-wire secondary does not magically become a "single voltage, two wire secondary" because of how the four wires are connected.

Sure it does, if that's how it's connected, as per the nameplate. The sections under question are all about conductor protection, so all that matters is the configuration of conductors passing through the transformer case. What's inside the case is immaterial.

Cheers, Wayne

 

[david luchini]

Not really. I'm merely saying that a dual-voltage, four-wire secondary does not magically become a "single voltage, two wire secondary" because of how the four wires are connected.

There's nothing magical about it. It's shown right on the transformer nameplate.

 

[wwhitney]

For those arguing that how the transformer is configured inside the case matters, suppose I buy one of these transformers, and it comes from the factory in the two wire (single voltage) secondary configuration I want to use, with documentation on how to internally rewire it for other configurations. Does that comply with the "two-wire (single voltage) secondary" language in question?

P.S. I suggest we keep the quoting accurate, I don't find "single voltage, two wire secondary" used anywhere in the NEC.

Cheers, Wayne

 

[Jerramundi]

"Rarity" is not relevant to the secondary conductor protection rules.

Your're intentionally choosing a definition of "special" which buttresses your argument and your argument alone.

There are clear and explicit definitions of the word "special" in Merriam-Webster that support BOTH
(1) the interpretation of "particularity" AND (2) the interpretation of "rarity."

Both are acceptable interpretations of the word "special."

As for this being relevant to the NEC based discussion, we are having, I will NOT concede that the interpretation of "rarity" is irrelevant.

"Rarity" could absolutely be used to support the idea that unless this transformer is manufactured with a single coil and only two wire leads, that it does not qualify as "2-wire (single voltage) secondary" per the availability of such a product. It's entirely plausible that we are not supposed to go without secondary protection except for "rare" instances in which a particular product, manufactured a particular way is utilized.

To your point, "particularity" could also be absolutely used to support the idea that "special" means as long as this particular transformer is wired according to its' nameplate to produce (1) two points of attachment for the secondary conductors and (2) the ability to produce only one voltage output that it is acceptable as a "2-wire (single voltage) secondary."

Both interpretations are absolutely plausible. Me, I'm going to err on the side of caution and assume this does NOT meet the parameters defined until I hear from a more official source.

However, all input is appreciated and your arguments are valid
We can simply agree to disagree.

If a more official source discerns that I am wrong, I will be the first to admit it and even thank you posing a valid argument which forced me to question my own view and learn something new.

For now, I am going to err on the side of being excessive. I would rather learn that I could have saved on cost, versus learn that I was installing something not to the proper safety regulations.

 

[mivey]

Then we're at an impasse.

The rule is such because the secondary circuit conductor amps directly correspond to a set ratio of the transformer primary amps during any fault. If we know the secondary fault amps then we will always know the primary amps and can set protection accordingly. This is not so with other configurations where the primary vs. secondary current ratio can change based on the fault type.