louver over main switchboard

[malachi constant]

I am the electrical engineer overseeing a new service installation. The service is located on an exterior wall. Above the service switchboard is a normally closed louver (unpowered - not a motorized damper). On the exterior side of the exterior wall is a two foot overhang protecting the louver. This is east facing, and in our region we don't see many storms from the east.

The electrical inspector has a concern - a legitimate one - about moisture getting into the room and on top of the switchgear, and has asked our mechanical engineer to write a letter giving his opinion (not a guarantee) that the service will stay dry.

The question I have is, how often have you guys seen exterior louvers over switchboards? I don't recall ever seeing it before, but can't say I've been looking that close. In your experience how bad an idea is this?

Don't pull punches - in our original layout of the room this louver was not near any equipment, but the equipment was installed differently than shown on plans. You're not going to hurt my feelings any. Thanks!

 

[Hendrix]

I am the electrical engineer overseeing a new service installation. The service is located on an exterior wall. Above the service switchboard is a normally closed louver (unpowered - not a motorized damper). On the exterior side of the exterior wall is a two foot overhang protecting the louver. This is east facing, and in our region we don't see many storms from the east.

The electrical inspector has a concern - a legitimate one - about moisture getting into the room and on top of the switchgear, and has asked our mechanical engineer to write a letter giving his opinion (not a guarantee) that the service will stay dry.

The question I have is, how often have you guys seen exterior louvers over switchboards? I don't recall ever seeing it before, but can't say I've been looking that close. In your experience how bad an idea is this?

Don't pull punches - in our original layout of the room this louver was not near any equipment, but the equipment was installed differently than shown on plans. You're not going to hurt my feelings any. Thanks!

How far above the switchgear is the louver? If it's above 6', you can build a shield.

 

[tom baker]

I have not seen louvers over switchboards but my exposure to a lot of installations is limited.
But take a look at the rules in 110.26(F) on dedicated spaces, it has section for indoor and outdoor locations, outdoors require the dedicated equipment space and the lover would appear to be not allowed.

 

[charlie b]

If the louver does not extend above the switchboard itself, if it is located entirely outside the building, and if the only risk is that rainwater could be blown into the room via the open louver, then none of the NEC rules come into play. A drip shield might be a good idea, but the 6-foot-above-the-board rule does not apply. I sincerely doubt that a mechanical engineer would sign a letter of the type you describe.

 

[malachi constant]

Charlie, you pretty much nailed it. NEC doesn't apply, mechanical isn't that thrilled with the idea of putting his name on the letter. He's going to talk to the inspector tomorrow and I was hoping to prop him up with a little "hey, people install it this way all the time and there's never any problems!" talk. But since I haven't seen it myself we can't say that.

Maybe I could flip it around...
Me: "We've never seen switchgear get any moisture in an installation like this - ever."
Inspector: "That's great. Um, have you ever seen an installation like this?"
Me: "Driving through a tunnel...I'm losing you...will have to call you back!"

 

[e57]

Not seeing a purpose for a fully closed louver - but it very well may be a 'drip shield' in of itself.... As for ventalation it may serve a purpose of make-up air, or pressure outlet? - but if not directly over the cabinet foot-print - I don't see a code violation...