ron
Senior Member
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- New York, 40.7514,-73.9925
This is a link to a pretty good article, if I must say so myself.
http://www.csemag.com/article/CA6290839.html
http://www.csemag.com/article/CA6290839.html
NEC 645 Might Not be for You
- Thread starter ron
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mdshunk
Senior Member
- Location
- Right here.
Re: NEC 645 Might Not be for You
Ron, that's a super article. The main thing that I learned is that an EPO button is not required. I guess that I always figured that computer rooms must have one.
Keep 'er coming...
Ron, that's a super article. The main thing that I learned is that an EPO button is not required. I guess that I always figured that computer rooms must have one.
Keep 'er coming...
Re: NEC 645 Might Not be for You
Great article Ron. As a main frame I/O cabling integration designer in the 80's, I certainly would hesitate to activate a panic button without a backup system. These days an IT room can be just about anything with the networked PCs that are so common. I see that 645 is needing additional ramifications on the IT versus main frame definition.
rbj, Seattle
Great article Ron. As a main frame I/O cabling integration designer in the 80's, I certainly would hesitate to activate a panic button without a backup system. These days an IT room can be just about anything with the networked PCs that are so common. I see that 645 is needing additional ramifications on the IT versus main frame definition.
rbj, Seattle
sandsnow
Senior Member
- Location
- Southern California
Re: NEC 645 Might Not be for You
It is a good article. It sums up the premise of the article well. Many designers and inspectors are under the misconception that an EPO is always required in an IT room.
This would be a great training handout.
One thing I will take issue with is this paragraph:
NEC Article 685 is used when "an orderly shutdown is necessary to ensure safe operation. There have also been instances in which the authority having jurisdiction (AHJ) has allowed an exemption based upon severe financial consequences or business disruption, but only when satisfied that an alternate method could ensure that equivalent objectives could be achieved, per NEC 90.4.
My first thought is that the word "safe" and "severe financial consequences" do not belong together. I can't think of an alternate method that would provide equivalent objectives. Further clarification from the author would have been great at this point.
In a past IAEI article the purpose or objective of the EPO was to shut down the source or possible source of ignition in relation to firefighting in the IT room. As I understood the IAEI article that was the reson non-plenum cable is allowed in an air handling space.
It is a good article. It sums up the premise of the article well. Many designers and inspectors are under the misconception that an EPO is always required in an IT room.
This would be a great training handout.
One thing I will take issue with is this paragraph:
NEC Article 685 is used when "an orderly shutdown is necessary to ensure safe operation. There have also been instances in which the authority having jurisdiction (AHJ) has allowed an exemption based upon severe financial consequences or business disruption, but only when satisfied that an alternate method could ensure that equivalent objectives could be achieved, per NEC 90.4.
My first thought is that the word "safe" and "severe financial consequences" do not belong together. I can't think of an alternate method that would provide equivalent objectives. Further clarification from the author would have been great at this point.
In a past IAEI article the purpose or objective of the EPO was to shut down the source or possible source of ignition in relation to firefighting in the IT room. As I understood the IAEI article that was the reson non-plenum cable is allowed in an air handling space.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: NEC 645 Might Not be for You
Larry,
I just spoke with the author about that paragraph ...
The reasoning behind this exception in 685 & 645, is that an AHJ has the authority to consider the datacenter compliant with 685, thus omitting the requirement of an EPO.
If an AHJ is "satisfied that an alternate method could ensure that equivalent objectives could be achieved", then the intent of an EPO requirement is not needed. For example, an AHJ allowed an EPO to be omitted (considering the room compliant with 685), because there was spot type smoke detectors and air sampling type smoke detection installed throughout the datacenter (defined as total coverage in NFPA 72). In addition, there are trained staff on site 24/7, and the local fire department was taken on yearly training exercises throughout the facility.
There are other things that can be done to mitigate the need for an EPO, in which an AHJ may be willing to accept in lieu of an EPO.
Of course the whole discussion is moot if the designer chooses not to use the leniencies in 645, and stays with Chapters 1-4, 7 & 8 for wiring methods. Then no EPO is required anyway. This is the approach of several datacenter designers. The risks of installing the 645 pre-requisites, are not worth the 645 leniencies in many cases.
Larry,
I just spoke with the author about that paragraph ...
The reasoning behind this exception in 685 & 645, is that an AHJ has the authority to consider the datacenter compliant with 685, thus omitting the requirement of an EPO.
If an AHJ is "satisfied that an alternate method could ensure that equivalent objectives could be achieved", then the intent of an EPO requirement is not needed. For example, an AHJ allowed an EPO to be omitted (considering the room compliant with 685), because there was spot type smoke detectors and air sampling type smoke detection installed throughout the datacenter (defined as total coverage in NFPA 72). In addition, there are trained staff on site 24/7, and the local fire department was taken on yearly training exercises throughout the facility.
There are other things that can be done to mitigate the need for an EPO, in which an AHJ may be willing to accept in lieu of an EPO.
Of course the whole discussion is moot if the designer chooses not to use the leniencies in 645, and stays with Chapters 1-4, 7 & 8 for wiring methods. Then no EPO is required anyway. This is the approach of several datacenter designers. The risks of installing the 645 pre-requisites, are not worth the 645 leniencies in many cases.
rick hart
Senior Member
- Location
- Dallas Texas
Re: NEC 645 Might Not be for You
It's the flexibility under the floor that requires the dreaded EPO or similar disconnect.
The catch is to wire an IT room with the outlets fixed, conduits, strapped and limits on the use of flex under a raised floor as required under Chapter 1 through 4. The computer geeks I know won't go for having their future restricted by the permanent wiring methods used in most common electrical sites.
It's the flexibility under the floor that requires the dreaded EPO or similar disconnect.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: NEC 645 Might Not be for You
Under 300.22, you could use flex all day long. You have to secure it.
Funny, many think that if your compliant with 645, you can install any type of flex and not secure it. If you don't want to secure it, it must be listed for IT equipment, not just any old type of field assembled whip. The IT listed whips are very expensive and generally not worth it, except to reduce field electrical work.
Under 300.22, you could use flex all day long. You have to secure it.
Funny, many think that if your compliant with 645, you can install any type of flex and not secure it. If you don't want to secure it, it must be listed for IT equipment, not just any old type of field assembled whip. The IT listed whips are very expensive and generally not worth it, except to reduce field electrical work.
- Location
- Massachusetts
Re: NEC 645 Might Not be for You
Ron I printed it out, I wish I could staple it to a few peoples forehead so they will remember it.
Ron I printed it out, I wish I could staple it to a few peoples forehead so they will remember it.
No doubt about that.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: NEC 645 Might Not be for You
Bob, sounds like it will be a Christmas present!
That's another struggle I have with facility operators, is that the cords they drop below the floor to plug into receptacles (or hardwire to j-boxes) are not DP rated.
Bob, sounds like it will be a Christmas present!
That's another struggle I have with facility operators, is that the cords they drop below the floor to plug into receptacles (or hardwire to j-boxes) are not DP rated.
mdshunk
Senior Member
- Location
- Right here.
Re: NEC 645 Might Not be for You
That begs an obvious question for me, then. Is there some type of DP/IT rated cable that is available in bulk reel form for making field whips, much like people noncompliantly use SJT or SJO? If so, what's that stuff called?
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