Raceways installed in cabinets?

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JJWalecka

JJWalecka

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New England
I have a question regarding raceways installed in cabinets. Does the raceway have to be securely installed with a connector?

3" PVC penetrates the Concrete slab into a 3 phase 800 Amp Transfer switch. The bottom support braces keep the 3" PVC penetrations 10" to 12" off the slab. Three and a half inch holes are punched and PVC Bushings are used bringing the PVC stubs four inches into the cabinet.

Article 312.5 (A) States Openings through which conductors enter shall be adequately closed.

300.5 (G) Mentions raceway seal but I don't believe this to apply to my question.

300.10 Proclaims; Unless specifically permitted elsewhere in this Code, raceways and cable assemblies shall be mechanically secured to boxes, fitting,cabinets and other enclosures.

Is this the correct installation; The three inch PVC is changed to rigid stubs, proper holes are punched, and bonding bushings are used.

Any feedback is always appreciated.

Justin W.
 
Re: Raceways installed in cabinets?

Justin the raceways should be connected to the enclosure as you have pointed out.

PVC, EMT, RMC any of them could be acceptable with a proper connector and bonding if applicable.

You can get open bottomed switch gear that you do not use connectors with but you would need bushings on the ends of each raceway.
 
Re: Raceways installed in cabinets?

Iwire,


The Main Switch Gear and Branch Circuit panels rest on the slab with an open bottom. PVC bushings are installed on all raceways.

Article 230.43 allows PVC to be used as you stated.

Rigid elbows are used, female connectors change the raceway to PVC and penetrate the bottom of the Transfer Switch with 8" to 10" nipples.
A few of the Rigid elbows penetrate the concrete slab, exposing the steel. Would the raceway be required to stay rigid and intern need to be Bonded?

250.92(A)(1,2&3) Basically states that a metallic raceway must be effectively bonded together.

Can the raceway be changed to nonmetallic as it penetrates the slab to eliminate the need of bonding?

I'm still searching. Any thoughts would be appreciated. Thank you for your time and effort.

Justin W.
 
Re: Raceways installed in cabinets?

If the exposed steel elbows are not already bonded by a steel raceway underground then yes they need bonding in some other way.

I would simply extend the RMC sweeps with EMT to the enclosure. At this point you would need to use reducing washers from the 3.5" KO to the 3" EMT which oddly enough UL says are rated for grounding. :roll:

Regardless of ULs blessing I would install grounding bushings on the EMT connectors and handle it that way.

[ January 02, 2006, 03:25 PM: Message edited by: iwire ]
 
Re: Raceways installed in cabinets?

Iwire,

Thank you. Another question on a Tangent.

For a Fire Pump cabinet. Rigid elbows are used but is changed to PVC. Most of the rigid elbow penetrate the slab and are extended to the cabinet and bonded. One of the penetrations is PVC and is changed to rigid by means of a PVC female connector as close to the slab as possible.

This would be an incorrect installation?

Would a Die cast compression connector used on the rigid steel be a violation because it is not of Steel?

695.6 (A) states that the supply conductors shall be routed outside. This includes underground.

695.6 (E) states that Rigid should be used
 
Re: Raceways installed in cabinets?

408.5 Clearance for Conductor Entering Bus Enclosures.
...The Conduit or raceways, including their end fittings, shall not rise more than 3 in. above the bottom of the enclosure.

Also see 250.80 (and exception) for the bonding of metallic elbows that are used for the service entrance conductors.
 
Re: Raceways installed in cabinets?

Pierre,


Thank you. LOL :) . I'm expecting my first child soon. I hope I can instill the same morals.

Justin W.
 
Re: Raceways installed in cabinets?

408.5 Clearance for Conductor Entering Bus Enclosures.
...The Conduit or raceways, including their end fittings, shall not rise more than 3 in. above the bottom of the enclosure.
Click to expand...
Does anyone know why the chosen dimension is 3"? This is a pretty small dimension especially when dealing with large conduits with large radius elbows. One of our typical installations would have a piece of strut across the floor with a strap to hold the conduit and an EMT connector with a bonding bushing on it. This would be on a building floor with the conduit run in the ceiling below. It is physically impossible to keep this arrangement under 3". Besides that, what purpose does this limitation serve?

I think that a limit based on the proximity of the conduit stub to the live busbars would be more practical.
 
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