Electrical Enclosure Made From Wood

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Saturn_Europa

Saturn_Europa

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Electrician Limited License NC, QMED Electrician
Is there a specific section in the NEC 2014 that prohibits electrical cabinets/enclosures being made from wood. I looked through chapter 1 and did not seeing anything. I also looked at Article 314.40(C).

OSHA of course bars it: Federal OSHA 1910.303(A)

Its amazing what people will come up on there own. I would never have even thought of building a control cabinet out of wood for a variety of reasons. Mainly because its Flammable!!! Not to mention it absorbs water and can attract bugs.
 
Saturn_Europa said:
Is there a specific section in the NEC 2014 that prohibits electrical cabinets/enclosures being made from wood. I looked through chapter 1 and did not seeing anything. I also looked at Article 314.40(C).

OSHA of course bars it: Federal OSHA 1910.303(A)

Its amazing what people will come up on there own. I would never have even thought of building a control cabinet out of wood for a variety of reasons. Mainly because its Flammable!!! Not to mention it absorbs water and can attract bugs.
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Not flammable but maybe combustible.

Can you elaborate on your question? What's in it and what's the application and occupancy classification?
Do you have buses mounted on wood?
Pictures tell a gazillion words!

Welcome to the forums!
 
Thank you for your reply. Its inside, VFD enclosure, with Softstart bypass. 3/4" plywood. Very neat, very organized, panduit. Exactly what you would expect to see running a 40 hp pump. Except its wood.
 
iwire said:
I looked, I do not see a wood ban in 1910.303(A).

However the NEC equivalent section is 110.3(A).
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1910.303(e)(1)
Identification of manufacturer and ratings. Electric equipment may not be used unless the following markings have been placed on the equipment:1910.303(e)(1)(i)
The manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the product may be identified; and
1910.303(e)(1)(ii)
Other markings giving voltage, current, wattage, or other ratings as necessary.

I guess it's a matter of interpretation. I took this to ban jury rigged or home made electrical equipment.
 
iwire said:
I looked, I do not see a wood ban in 1910.303(A).

However the NEC equivalent section is 110.3(A).
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He's probably thinking indirectly. 1910.303A requires the equipment to be acceptable and points to 1910.399 for the definition. I suppose you might raise a few eyebrows at an NRTL if you submitted your wood enclosure for listing.
 
In Minnesota there is statute that addresses one-off custom assemblies not intended to be resold. Seeing you are in North Carolina, maybe there is similar statute?

Below is the relevant section of Minnesota statute.

Minnesota Administrative Rules
3801.3620 APPROVAL OF ELECTRICAL EQUIPMENT.
Subp. 3. Equipment exempt from listing requirements.
D. Custom-made electrical equipment or related installations that are designed and manufactured to a purchaser's specifications and are not marketed to the general public are exempt from listing and labeling requirements. Equipment or installations exempt under this item are subject to the following:

(1) they must be determined to be safe for their intended use by the manufacturer on the basis of test data which the purchaser keeps and makes available to the electrical inspection authority having jurisdiction, as required by Code of Federal Regulations, title 29, section 1910.399 (1991), for equipment or installations subject to national occupational safety and health laws; or

(2) they must be inspected by the electrical inspection authority having jurisdiction for compliance with the construction requirements of the applicable electrical standards used by electrical testing laboratories to evaluate the equipment, or the National Electrical Code. Schematic wiring diagrams, component layout diagrams, and component electrical rating information shall be provided to enable evaluation under this subitem.
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gadfly56 said:
He's probably thinking indirectly. 1910.303A requires the equipment to be acceptable and points to 1910.399 for the definition. I suppose you might raise a few eyebrows at an NRTL if you submitted your wood enclosure for listing.
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Not all enclosures are required to be listed.
 
The NEC does not prohibit me from making an electrical enclosure out on graham crackers and marshmallows either.

My brain does...

Wood does not provide any shielding for EMI/RFI emissions, and is a thermal insulator. That makes it an absolutely TERRIBLE choice for housing a VFD and a soft starter.
 
It sounds to me like there are semantic issues. The VFD is in an enclosure. I don't see any indication of open wiring. The term "Panduit" doesn't mean anything. If it is Panduit raceway then there should be no problem. If it is Panduit wiring duct and not listed as a raceway then wiring that isn't allowed free air is not going to be allowed in the wooden decorative enclosure. There are requirements for wireways, junction boxes and panelboard materials.
 
Electrical devices have been in wood cases since the beginning of Electricity. Just look at the old Tub Radios. Sure they had a metal chassis, but they were stored in large electrical cabinets. Many at Voltages up to 250V.

When I read his comments, it looked like the VFD was mounted on Plywood. I wouldn't call that an enclosure, just a Mounting point. Unless I'm missing something here.
 
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