HVAC Duct Over Switchgear
HVAC Duct Over Switchgear
(OP)
Is there any rule not to route an HVAC duct over a switchgear or a switchboard. I assume that there are instances where condensed air liquify to water and drift on the MCC/Switchgear/switchboard. In this case I may establish to avoid routing HVAC ducts over these electrical equipment. Any comments?
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata






RE: HVAC Duct Over Switchgear
RE: HVAC Duct Over Switchgear
RE: HVAC Duct Over Switchgear
Per NEC 110.26(F)(1)(a), "the space...extending from the floor to a height of 1.8m (6 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. No ... ducts... or other equipment foreign to the electrical installation shall be located in this zone."
The NEC Handbook goes on to explain that you can't put any ducts in that dedicated space, but you can put ducts in ABOVE that dedicated space so long as you drip pan them.
RE: HVAC Duct Over Switchgear
I know what the NEC says, but you will have to get ductwork into the room, and in many rooms it will be difficult to do this without infringing on the space somehow.
RE: HVAC Duct Over Switchgear
The installation assumed that somehow the HVAC duct leaked water. The "gutter", a pan about 3' wide assured the water never got near the gear.
RE: HVAC Duct Over Switchgear
RE: HVAC Duct Over Switchgear
Looking at some of your other postings in this forum, I guess that you are in the UK somewhere, in which case all these references to the NEC (US National Electrical Code) are pointless for you. Maybe some of our other UK members can lend their experience, but for future reference (and for the benefit of other readers who are thinking of posting), when asking about "rules" etc. it is a good idea to state where you are located. Rules vary from country to country.
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RE: HVAC Duct Over Switchgear
Going back to the subject matter, the concern is that based from the HVAC details, the diffuser take out is facing downwards to the top of the equipment and this were the concern is. I am thinking of coordinating with the HVAC designer to re-route his HVAC ducts avoiding the top of the switchgears or placing the take-out diffusers on the sides of the duct (if this is possible). Any suggestions?
Another HVAC duct is routed above the MCCs but it this duct is for the In-take diffusers. This is not a concern since the air goes inside and there is no possibility of water drifting out...(any comments?)
Hoping for your suggestions since I am still arranging things up with our design contractor. Thanks
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata
RE: HVAC Duct Over Switchgear
There are two possible problems;
1> The air in the duct is warmer than the ambient temperature of the space through which the duct passes.
If the ambient temperature falls below the dew point of the air in the duct, there is a possibility of condensation on the inside surfaces of the duct.
2> The air in the duct is cooler than the ambient temperature of the space through which the duct passes.
If the temperature of the air in the duct falls below the dew point of the ambient air in the space through which the duct passes, there is a possibility of condensation on the outside surfaces of the duct.
respectfully