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Cutting out bottom of electrical panel

15K views 47 replies 17 participants last post by  Journeymanjoe 
#1 ·
Currently getting some negative vibes about cutting the bottom out of a panel to place on house keeping pad to accommodate for all of underground branch conduits. They are unable to cite code article saying I cannot cut it out. Any suggestions? 300.12 exception 2 says I can
 
#8 ·
I bet if you cut it out it no longer meets the UL listing for the product.

Your best bet would be to get written permission from the panel manufacturer stating that if you cut out the bottom it still meets the UL listing.
 
#12 ·
Cut out the bottom of a j-box or trough, which do not require a UL listing. Put open bottom box tight to slab and mount panel directly on top. Chase nipple from panel into box. Collect check. Forget about the scabby pipe work and think about pretty girls as you drive to the bank.

Don't forget bonding bushings if you stubbed up with rigid.
 
#15 ·
CHAPTER: 3 Wiring Methods and Materials
ARTICLE: 300 Wiring Methods
SECTION: I. General Requirements

300.12 Mechanical Continuity — Raceways and Cables

Metal or nonmetallic raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets.

Exception No. 1: Short sections of raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be mechanically continuous.

Exception No. 2: Raceways and cables installed into the bottom of open bottom equipment, such as switchboards, motor control centers, and floor or pad-mounted transformers, shall not be required to be mechanically secured to the equipment.

Notes: Exception No. 2 to 300.12 specifically permits raceways and cables to enter switchgear from below without actually being attached to the underside of the switchboard, motor control center, or transformer where the equipment is constructed with an open-bottom feature. Where metal raceways or cables enter open-bottom-type equipment, electrical continuity between the wiring method and the equipment as required by 300.10 must be ensured.
 
#21 ·
300.12 Mechanical Continuity — Raceways and Cables

Metal or nonmetallic raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets.

Exception 2 does not apply to cabinets.

Swtichboard, panelboard, and switch gear have their own definitions in the NEC.
 
#30 ·
The exception says "such as" meaning it's not exlusive to only switchboards, MCCs, and trannys.

That section specifically allows open-bottom equipment, so unless you can find something saying a panel board cannot be mounted in an open-bottom cabinet it seems legal to me. And from a practical standpoint it seems silly to argue it would be okay on a 4000A switchboard but not a 200A panel board.

OP just needs to be sure he bonds his conduit to comply with 300.10
 
#24 ·
So you are telling me that 300.12 which starts out with saying raceways have to be continuous between cabinets but then says just kidding exception two basically says you can do what ever you want.

Like I said before do what ever you want but 300.12 is not your scapegoat.

300.12 Mechanical Continuity — Raceways and Cables

Metal or nonmetallic raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets.
 
#41 ·
It is required to be designed for the purpose.

Personally, I would not cut out the bottom of a panel w/out having a discussion with the AHJ. I have been known to do and ask forgiveness, but this is one where a phone call can save a headache.
 
#37 ·
Who wants to be the guy that has to have written permission to knock out a hole in an enclosure:

:eek:

The UL Mark applies to the product as it is originally manufactured when shipped from the factory. Authorized use of the UL Mark is the manufacturer's declaration that the product was originally manufactured in accordance with the applicable requirements. UL does not know what the effect of a modification may have on the safety of the product or the continued validity of the UL certification mark unless the field modifications have been specifically investigated by UL. Unless UL investigates a modified product, UL cannot indicate that the product continues to meet UL's safety requirements.

The only exception for a field modification authorized by UL is when the product has specific replacement markings. For example, a switchboard may have specific grounding kits added in the field. The switchboard is marked with a list of specific kit numbers that have been investigated for use in that particular switchboard. Only grounding kits that are included on the product have been investigated for use in that product.


http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073983908&sequence=1
 
#42 ·

Similar setup. Has passed inspection in two states. The second pic is before the conduits were cut down. 10" gutter then 7'6" panel. We will have to rivet off a few breaker spots to meet the 6'6" aff but sh*t happens. The person who thought up this tall of a can needs whipped.

I wouldn't cut the bottoms out of the cans though. That's just asking for a headache with the ahj


Sent from my iPhone using Tapatalk
 
#44 ·
tates1882 said:
Similar setup. Has passed inspection in two states. The second pic is before the conduits were cut down. 10" gutter then 7'6" panel. We will have to rivet off a few breaker spots to meet the 6'6" aff but sh*t happens. The person who thought up this tall of a can needs whipped. I wouldn't cut the bottoms out of the cans though. That's just asking for a headache with the ahj Sent from my iPhone using Tapatalk
I haven't been involved with a job that allowed PVC to be used inside above ground for at least 7 years
 
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