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#174209 - 01/29/08 07:58 AM New article 708, Critical Operations Power Systems  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,208
Chesapeake, VA
I was merrily tabbing my new NEC 2008 when - wow - new article! With some unexpected surprises. From what I gather, article 708 "Critical Operations Power Systems (COPS)" was based in large part on Army Corps of Engineer tech manuals which I've already been using for years, and most of the article is common sense stuff finally put to paper, but there were a few points that I'm not quite clear on. Or maybe I am perfectly clear on, but just don't want to believe it. What's your all take on this?

709.10(C) appears to essentially prohibit EMT, cable trays and cable trenches from pretty much anything connecting to a generator or UPS upstream of the final power distribution unit/branch panel. Are cables allowed to be exposed when transitioning between duct banks in manholes?

708.10(C) requires 1-hour fire resistance on all feeders... is THHN in IMC 1-hour fire resistant?

708.14(1) requires all signal and communications wire to be shielded twisted pair. Does this apply to thermostat bell wire? And #14 alarm cabling? I don't believe I've seen shielded twisted pair in gauges that large. I can see the IT guys going nuts over this one, too, though honestly, there's no reason NOT to be using shielded Cat5 for critical applications.

708.14(8) further requires HVAC cables (including shielded bell wire?) to have a 2-hour fire rating.

708.22(A) appears to require prime-rated generators, even in standby applications.

708.52(B) appears to require individual ground fault protection on all circuits of a ground-fault protected wye switchboard. Coordinated, too, I'd hope, though coordination isn't explicitely mentioned. Makes sense, but I don't think I've seen this on any LV switchgear.

Last edited by SteveFehr; 01/29/08 08:04 AM.

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#178616 - 06/06/08 03:49 PM Re: New article 708, Critical Operations Power Systems [Re: SteveFehr]  
earlydean  Offline
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Joined: Dec 2003
Posts: 751
Griswold, CT, USA
708.10(C)(2) requires LISTED fire ratings. One merely checks the UL White book for listed fire rated assemblies.

It will be interesting when the building codes catch up.


Earl

#178627 - 06/06/08 09:30 PM Re: New article 708, Critical Operations Power Systems [Re: earlydean]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
A few points to ponder ...

Fire ratings are in the three UL "Orange books."

There is no way that wire in pipe has any fire rating. While it may not harm a fire wall by passing through it, that's a different matter from protecting the wires. The most "generic" way to make a 1 hr rated barrier is to have two layers of 5/8 drywall.

Finally, I am given to understand that 708 is an annex, if you will, to some of that "homeland security" stuff. As such, I expect that 90% of the problem will land on the architect's desk.


#178690 - 06/09/08 12:26 PM Re: New article 708, Critical Operations Power Systems [Re: renosteinke]  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,208
Chesapeake, VA
708 is no annex, it's an article just like 701 and 702. And probably driven by the fed going wild with cancelling all the old guidance in favor of commercial standards before waking up and realizing that, "Hey, we actually needed some of that special stuff after all..."

My interpretation of 708.10(C) is that the feeder conductors themselves be protected and functioning for 1-hour in a fire. Which makes perfect sense for the COPS this article applies to. We're not talking wal-mart here, we're talking missile silos, comm centers, etc.

Dean, 708.10(C)(1) and (4) requires a listing; 708.10(C)(2) does not, and appear to allow a 1hr assembly to be built up from gypsum. Will we start seeing RMC lagged like pipe, I wonder?

Which is funny, as probably 90% of the existing COPS installations out there are just using EMT or open cable tray...



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