Changing Data Center Air Conditioning - Raised Floor ->

[brannen]

Hi All,

I'm a Network Engineer looking to get out of IT and have been studying the NEC code in preperation for my Limited License - Low Voltage exam next month.

I work for a company in which we have a Data Center with about an 8" raised floor. The Data Center was very poorly designed originally - which is being corrected. For instance, the inadequate Air Conditioning is all down draft and attempts to blow cool air down on the computer cabinets, all the network cabling is home run with no patch panels, the raised floor was inadequate to support the weight, etc. etc.

We've begun work on moving the network cabling under the floor (which is all CM listed) and putting in structured cabling above the dropped ceiling.

However, the Air Conditioning work is moving faster than the cabling. The Air Conditioning is being replaced with down draft units which will have the effect of pressurizing the floor and blowing cold air up into the cabinets.

My question is -> If they put the Air Conditioning in BEFORE the data cabling is removed, this will be changing the air space into plenum space - where there is already NON plenum cable.

I can see where the NEC specifies Plenum or Riser rated cabling be installed in Plenum space - what if the cable is there first and the space is converted to plenum? What about the other cabling - flexible electrical "tails", cabling for the fire detection, for the camera and proximity card readers, large quantity cabling from the phone switch to the phone block wall, etc?

Would putting in AC and converting the space to plenum without changing the existing cabling be a violation? Would it be a electrical code violation, fire, or mechanical code?

Just want to get my ducks in a row before I point this out to management.

Thanks for your help.

 

[ron]

Re: Changing Data Center Air Conditioning - Raised Floor ->

Is the installation compliant with Article 645.2?
If so, plenum rated cable is not required.

 

[brannen]

Re: Changing Data Center Air Conditioning - Raised Floor ->

Hi Ron, thanks for the reply.

Yeah, it looks like 645.2 covers the room. There's only computers & network gear in there, it has its own power and air conditioning, and the only people that go in are in there only temporarily to operate the equipment.

So, in that case, plenum rated cabling is not required in plenum space?

 

[ron]

Re: Changing Data Center Air Conditioning - Raised Floor ->

645.2 also includes EPO's at each principal exit and HVAC shutdown when smoke is detected below the floor, etc. If the space is in compliance with all of 645.2. then 645.5(D)(5)(c) states that the cabling is permitted to be plenum rated but not required.

 

[brannen]

Re: Changing Data Center Air Conditioning - Raised Floor ->

Out of curiosity, and learning, what would happen if this wasn't a Data Center?

What if this was a normal business, and they decided to change the air intake into the ceiling instead of a vent - to change the ceiling space to plenum space and there was already non-plenum rated cabling in place - before the plenum space was plenum space? Is the cabling "grandfathered" in, or does it have to be replaced?

 

[ron]

Re: Changing Data Center Air Conditioning - Raised Floor ->

I would assume it depends on if they got caught. Seems like a change in use and requires evaluation of all aspects of the installation.

 

[brannen]

Re: Changing Data Center Air Conditioning - Raised Floor ->

I guess I'm wondering hot an AHJ would handle a situation where a different trade (HVAC) changes the environment which changes the cabling requirements.

Is it the HVAC guys responsibility to make sure the electrical passes inspection if they change the space to plenum?

Or would the Fire Insepector catch it - would they go to the building owner and say "fix it" or would it be the responsibility of the HVAC sub or the electrical sub?