NEC & Barn Requirements

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  #1  
Old 08-30-06, 09:22 PM
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NEC & Barn Requirements

A bit off the residential electric topic, but I'm hoping someone can help.

We've been discussing adding a roof vent/fan to the hayloft of an existing barn. The initial plan was to install a normal residential 2200CFM roof vent, but I recall reading some information about a hayloft being considered an "explosive environment" as far as the NEC is concerned, and therefore requires specific rated equipment.

Any ideas if this is true? I want to be sure that the correct fan is installed in the correct manner for this environment.

Thanks in advance for your help.

-Mike
 
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Old 08-30-06, 11:07 PM
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Good question!
I've looked through Article 500 and my GUESS might be that it meets the requirements of a Class III, Division 2 location for Hazardous Locations.

See if you can get a copy of the NEC (library even) and scan Articles 500-503. This can prep you for the advice that may come from better experts in this area.
 
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Old 08-31-06, 03:18 AM
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Electrician are required to know how to properly wire various classified locations. Electricians are not quialified to classify the location.

Someone who has done enough hay lofts may want to tell you what this area is likey to be, but the real answer rests with the AHJ or he may want an engineere to tell you.
 
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Old 08-31-06, 06:28 AM
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I appreciate the responses. I'm a step further ahead in at least sounding smarter when I'm talking to other about it.

Thanks for your help.

-Mike
 
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Old 08-31-06, 07:51 AM
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NEC 2005 Article 547 Agricultural Buildings
547.7 Motors and other rotating electrical machinery shall be totally enclosed or designed so as to minimize the entrance of dust, moisture or corrosive particles.
This also goes for junction boxes, lighting fixtures, etc.
Other NEC articles may also apply to your situation.
Is it going to be inspected?
What type wiring do you have in the barn?
Do you house livestock?
 
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Old 08-31-06, 05:17 PM
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Is it going to be inspected?#

Disregard this question!!!!! Do it correctly, You have a vested interest!!!
 
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Old 08-31-06, 08:05 PM
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Originally Posted by hillbilly ace
Is it going to be inspected?
What type wiring do you have in the barn?
Do you house livestock?
Ace, thanks for the info. I think that's the info I was looking for. It's not going to be inspected (they only inspect major renovations), but I still want to do it correctly nonetheless as lectriclee noted. I figured I could probably just cut a hole in the roof and stick a box fan out it...

Most of the wiring in the barn is in PVC conduit (THHN), though there is some NM (which probably shouldn't be there). The barn houses horses.

There's not an excessive amount of dust or particulate matter in the air, but still, I'd rather spend a bit extra to do it right. I've been looking into Class III Division 2 listed exhaust fans, and I haven't had much luck. Any idea who would sell a fan approved for use in this type of environment?

Thanks again for all your assistance,
Mike
 
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Old 09-01-06, 10:15 AM
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Originally Posted by Zorfdt
I've been looking into Class III Division 2 listed exhaust fans, and I haven't had much luck. Any idea who would sell a fan approved for use in this type of environment?
You might be better served by a roof-top unit, where the motor is not in the hazzardous environment. It may also be why you can't find the explosion proof units.
 
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Old 09-01-06, 03:19 PM
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Originally Posted by scott e.
You might be better served by a roof-top unit, where the motor is not in the hazzardous environment. It may also be why you can't find the explosion proof units.
That old trick only works for supply fans. Exhaust fans are taking the "hazardous" air out and the haz location extends the lenght of the duct, and If I remember right 10 foot beyond.

Unless you are talking about some kind of belt driven motor that I have never seen.
 
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Old 09-01-06, 08:02 PM
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Originally Posted by jwhite
That old trick only works for supply fans. Exhaust fans are taking the "hazardous" air out and the haz location extends the lenght of the duct, and If I remember right 10 foot beyond.

Unless you are talking about some kind of belt driven motor that I have never seen.
Now that you mention it, the application I was thinking of was a supply fan. The building had positive pressure. It was a pumping station for liquified petroleum products. But that could work in this situation also. They could use supply fans on the roof or gables and then use vents to "releive" the pressure.
 
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Old 09-02-06, 08:30 AM
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Originally Posted by lectriclee
Is it going to be inspected?#

Disregard this question!!!!! Do it correctly, You have a vested interest!!!
Disregard this question????
If it's going to be inspected, some inspectors have the habit of inspecting more than they're called to inspect.
The reason I asked the other questions was because if the inspector gets nosy (which they sometimes do), he may hit you for other violations in the barn (NM wiring for one). Also, if you have any concrete floors that the animals reside on regularly, he could hit you for not having a equi-potential plane.
Other things...GFCI receptacles, bonding, rated fixtures, etc.
By all means, do it right...but...the other things that are not done right can become a problem with a nosy inspector.
steve
 
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Old 09-03-06, 06:25 AM
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That is true enviroment is to be considered. for example never smoke in a plant that makes flower the dust is explosive it can cause a flash fire whereby everybody is dead in seconds. A barn hey dust maybe a consideration also
 
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