Article 645 Revisited (2017 version)

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Ohno Raccoon

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Fairfax, VA
Hi everyone,

So I've been looking at Article 645. I am familiar that everyone usually says that it's an optional article and to avoid it if possible.

Currently, I'm working on a project that has adopted 2017 NEC and they are requiring us to comply with 645.10 and 645.11. The AHJ is pretty set on requiring the article. I'm looking for verbiage that would suggest that this entire article is not required and or is a "permissive rule", but can't find it. . Am I missing something or has this changed?

Thanks
 

infinity

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Location
New Jersey
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645 is an optional Article, if you design using it then you have some relaxed wiring methods like flexible cords under the raised floor but then other more strict requirements are required like in 645.10 for a disconnecting means for all electronic equipment.

645.10 Disconnecting Means. An approved means shall be provided to disconnect power to all electronic equipment in
the information technology equipment room or in designated zones within the room. There shall also be a similar approved
means to disconnect the power to all dedicated HVAC systems serving the room or designated zones and to cause all required
fire/smoke dampers to close. The disconnecting means shall comply with either 645.10(A) or (B).
 

ron

Senior Member
645.4 tells you that you can use the alternative wiring methods in 645 if you do all the prerequisites found in 645.4 (1) through (6). If you don't do those prerequisites, then you can't use the alternative wiring methods and must go back to Chapter 3 and 725 and 770 like regular.

645.4 Special Requirements for Information Technology Equipment Room. The alternative wiring methods to Chapter 3 and Parts I and III of Article 725 for signaling wiring and Parts I and V of Article 770 for optical fiber cabling shall be permitted where all of the following conditions are met:

BTW, not enforceable, but the editorial text in the NEC Handbook includes work such as " if any one of the six conditions is not met, wiring methods installed in the ITE room must follow the applicable requirements of chapter 3. "
 

Ohno Raccoon

Member
Location
Fairfax, VA
645 is an optional Article, if you design using it then you have some relaxed wiring methods like flexible cords under the raised floor but then other more strict requirements are required like in 645.10 for a disconnecting means for all electronic equipment.
So I've seen people saying "645 is an optional Article" a lot. But is there an exact statement from the NEC that we can reference indicating so?

In my case especially, regarding 645.11 we have a UPS over 750watts. It states we shall comply with 645.10.
645.11 Uninterruptible Power Supplies (UPSs). Except for installations and constructions covered in 645.11 ( 1) or (2), UPS systems installed within the information technology equipment room, and their supply and output circuits, shall comply with 645.10. The disconnecting means shall
also disconnect the battery from its load.
(1) Installations qualifying under the provisions of Article 685
(2) Power sources limited to 750 volt-amperes or less derived either from UPS equipment or from battery circuits integral to electronic equipment

Do the mentions of Art. 685 help?
No, I don't believe so.

645.4 tells you that you can use the alternative wiring methods in 645 if you do all the prerequisites found in 645.4 (1) through (6). If you don't do those prerequisites, then you can't use the alternative wiring methods and must go back to Chapter 3 and 725 and 770 like regular.

645.4 Special Requirements for Information Technology Equipment Room. The alternative wiring methods to Chapter 3 and Parts I and III of Article 725 for signaling wiring and Parts I and V of Article 770 for optical fiber cabling shall be permitted where all of the following conditions are met:

BTW, not enforceable, but the editorial text in the NEC Handbook includes work such as " if any one of the six conditions is not met, wiring methods installed in the ITE room must follow the applicable requirements of chapter 3. "
So when I spoke with the AHJ about 645.4, they said that only pertains to wiring methods within the room and that the requirement they are citing for the UPS (645.11) is a separate requirement. So are we saying that 645.4 is a permissive statement that applies to the entire Article 645?
 
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infinity

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Location
New Jersey
Occupation
Journeyman Electrician
Article 645 is a design choice not a requirement if the AHJ is requiring a complaint 645 installation he is not following the NEC. As Ron stated you can comply with the Article as a whole or if you cannot include the required elements then you can design to Chapter 3.
 

ron

Senior Member
The first prerequisite is 645.4(1) Disconnecting means complying with 645.10 are provided.

If you choose not to comply with that, then you do not get to use the leniencies in 645 :( :)

The NEC language has changed a little since 2005, but the meaning is the same, here is one of my favorite articles where the word "optional" is used 3 times
 
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Ohno Raccoon

Member
Location
Fairfax, VA
Article 645 is a design choice not a requirement if the AHJ is requiring a complaint 645 installation he is not following the NEC. As Ron stated you can comply with the Article as a whole or if you cannot include the required elements then you can design to Chapter 3.
Again, is there any NEC verbiage you can cite that states that Article 645 is a design choice? 645.4 (2011) used to to say
This article shall be permitted to provide alternate wiring methods to the provisions of Chapters 1 through 4 for power
wiring, 725.154 for signaling wiring, and 770.113(C) and Table 770.154(a) for optical fiber cabling when all of the following conditions are met:

With that verbiage I applied the entire Article 645 to the permissive statement of 645.4. But in 2017 it says
The alternative wiring methods to Chapter 3 and Parts I and IIII of Article 725 for signaling wiring and Parts I and V of Article 770 for optical fiber cabling shall be permitted where all of the following conditions are met.

No longer does it reference this article. And where does it say that 645.11 (or any other article within Article 645) is contigent on the application of 645.4? Is it for any section in Chapter 3 that overlaps with Article 645? Because, to my knowledge Chapter 3, doesn't cover disconnect requirements for the electronic equipment or the UPS.

The first prerequisite is 645.4(1) Disconnecting means complying with 645.10 are provided.

If you choose not to comply with that, then you do not get to use the leniencies in 645 :( :)

The NEC language has changed a little since 2005, but the meaning is the same, here is one of my favorite articles where the word "optional" is used 3 times
The NEC language may have changed a little, but the verbiage has certainly changed enough to make a difference in interpretation. Do you believe this article still holds based on the revised verbiage in 645.4 I pointed out from 2017 above?
 

infinity

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Location
New Jersey
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Journeyman Electrician
This section that you posted is under the heading:
645.4 Special Requirements for Information Technology Equipment Room.
The alternative wiring methods to Chapter 3 and Parts I and IIII of Article 725 for signaling wiring and Parts I and V of Article 770 for optical fiber cabling shall be permitted where all of the following conditions are met. "

It says shall be permitted. It is not a requirement to use them.
 

Ohno Raccoon

Member
Location
Fairfax, VA
This section that you posted is under the heading:


It says shall be permitted. It is not a requirement to use them.
Yes, i read that....but what you are saying doesn't address what I'm asking in my post.

So my interpretation of what you're pointing out to me in 645.4 (2017) is that any requirements of Article 645 that overlap requirements of Chapter 3 and Parts of Articles 725 and 770 shall be permitted (not required) to be used as an alternative wiring method. Where does that leave any paragraphs in Article 645 that do not overlap with Ch 3 or Articles 725 and 770?
 
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