24VDC Power Supply in a Class I Div II Area

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Aubrey M

Member
Location
Sioux Falls, SD USA
Hey folks I appreciate any help in advance.
I am tasked with putting a 24VDC 100W power supply in Div II location to supply power to a couple of strobes and a horn. Previously this "Alarm Station" was built using a Div I explosion proof enclosure which is heavy with less space inside for the Din Rail, Power Supply and Terminal Blocks.
So, I have been researching and getting quite confused by all of the NEC requirements. Can I use a Div. II enclosure and fittings for the AC input and DC output along with a Div II power supply, or possibly even a non-rated power supply if the enclosure is also Nema 4X or is the big cast aluminum Div I XP enclosure necessary?
Thanks again in advance for the help and any other advice and recommendations regarding the best ways to do this are very welcome.
 
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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Aubrey M said:
If I use a C1D2 power supply can I put it in a Weatherproof box and meet the requirements or is a Div2 enclosure still required since I will likely need Div2 connectors or cable glands?
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There is no such thing as a "div 2" enclosure.

take a look at 500.7 (G).

If the equipment is listed as non-incendive it can be used in a C1D2 area. You need go no farther.

The enclosure type rating should be based on the environment the enclosure is located in.

Read the instructions the NI equipment comes with and follow them.
 
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Dale001289

Senior Member
Location
Georgia
Aubrey M said:
If I use a C1D2 power supply can I put it in a Weatherproof box and meet the requirements or is a Div2 enclosure still required since I will likely need Div2 connectors or cable glands?
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Enclosures are either 'required to be explosion proof' or they're not. If the power supply is rated for CID2 environment, there would be no need to use an explosion proof enclosure, such as Nema 7 with threaded hubs. You could use a sheet metal enclosure such as Nema 4X (you wouldn't need to seal) but you'd still need to bond to the enclosure per 501.30.
 
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Aubrey M

Member
Location
Sioux Falls, SD USA
Dale001289 said:
Enclosures are either 'required to be explosion proof' or they're not. If the power supply is rated for CID2 environment, there would be no need to use an explosion proof enclosure, such as Nema 7 with threaded hubs. You could use a sheet metal enclosure such as Nema 4X (you wouldn't need to seal) but you'd still need to bond to the enclosure per 501.30.
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Thanks again for all of the help and clarification. Now for a really dumb question....is there a place I can download the NEC? I searched and ended up at the NFPA website and got lost soon thereafter. :?
 
rbalex

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Aubrey M said:
Thanks again for all of the help and clarification. Now for a really dumb question....is there a place I can download the NEC? I searched and ended up at the NFPA website and got lost soon thereafter. :?
Click to expand...
This is the page you want.

You can also get an Apple or Android app.
 
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Dale001289

Senior Member
Location
Georgia
MRKN said:
Your company should purchase it for you if it's required for your work.
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Back in the 'good ol days' companies used to spring for Code books... OR you could purchase them dirt cheap locally, usually at distributors like Greybar.
Times have changed.
 
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Aubrey M

Member
Location
Sioux Falls, SD USA
I asked a few others here at the company and I now have a hard copy on my desk!
Reading through the codes I noticed mention of Line Power being incendive. Do you guys know if I need to do anything other than proper bonding on my Line power coming into the power supply and my 24VDC lines going to the alarms?
I would like to connect everything to the enclosure with plugs and cables ideally.
Any thoughts or suggestions?
 
P

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Aubrey M said:
I asked a few others here at the company and I now have a hard copy on my desk!
Reading through the codes I noticed mention of Line Power being incendive. Do you guys know if I need to do anything other than proper bonding on my Line power coming into the power supply and my 24VDC lines going to the alarms?
I would like to connect everything to the enclosure with plugs and cables ideally.
Any thoughts or suggestions?
Click to expand...

I don't know what you mean by line power being "incendive". Can you cite the code reference that states that?

Take a close look at 501.140 and see if you qualify to use plug and cord connections.
 
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Aubrey M

Member
Location
Sioux Falls, SD USA
I've lookwd back through the book but can't find where I saw it mention about Line Power being incendive. It was probably on a website trying to explain the NEC without actually posting everything.
Looking over 501.140 and other info this morning it looks like I could get away with a plain old weatherproof enclosure with I used sealed cable glands made for Div2 locations as long as I have the Div2 power supply.
I think I'm going to play it save and put my Div2 power supply in a Stainless Steel Nema 4X enclosure that will meet Div2 requirements with Div2 cables and plugs. At least that's the plan for now until someone says, "That cost too much" then I may have to rework my BOM a little.
Thanks for all the help from everyone.
I love the FORUM!
 
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