Use of type G or GC conductors

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charlie b

charlie b

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Semi-Retired Electrical Engineer
I am involved in a residential building project (big money client!) that includes a room that will sit on rails and that can be moved about 20 feet (to give the resident and his guests a better view). My role is power design, but another engineering office is handling the power supply interface between the stationary and movable rooms. They want to use type G or GC cable. My reading of table 400.4 tells me these can be used in ?portable and extra hard usage? applications. My reading of article 400.7(9) tells me that these can be used for the connection of moveable parts (i.e., the ?sliding room?). However, I am concerned about 400.8(6), which prohibits their use ?where installed in raceways except as otherwise permitted in this code.?

The present plan is for me to bring power to a junction box (or perhaps a disconnect) located in a small building about 30 feet from the ?sliding room.? The wires would go underground that 30 foot distance, at which point the other engineering company will place a cable reel, a festoon system, or some other flexible method of bringing power to the ?sliding room.? I have no idea what is planned for that system, and so I don?t know how much, if any, of the cabling will be visible.

Questions:

  1. How do I go about finding out if the placement of types G and GC within an underground raceway is ?otherwise permitted in this code??
  2. Do I need to tell the other engineering company that their method needs to allow the type G or GC cable to be visible throughout its length?
 
I don't see why there would even be a need to install flexible cable in the underground raceway portion. The flexible cable should only be from the cable reel to the moving room.

If they do go with flexible cable for the underground portion, as long as the conduit is not terminated at either end, it is being used as a sleeve or chase, not as a raceway.
 
It doesn't look like G-GC is listed for damp or wet locations. isn't a underground raceway considered a damp or wet location?
Just throwing that out here.

Edit: Found this on southwires site

Type G & G-GC cables are suitable for use in industrial and light- to medium-duty mining applications, heavy-duty
service as power supply cable, power cable for mobile and portable electrical equipment at a continuous conductor
temperature of 90?C. Type G & G-GC cables may be used in marina (wet) applications. Type G & G-GC cables are
suitable for use on three-phase AC systems where 3 or 4 conductors are needed and grounding is required.
Excellent flexibility, resistance to oils, solvents, ozone, aging, and abrasion.
 
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Smart $ said:
I don't see why there would even be a need to install flexible cable in the underground raceway portion. The flexible cable should only be from the cable reel to the moving room.

If they do go with flexible cable for the underground portion, as long as the conduit is not terminated at either end, it is being used as a sleeve or chase, not as a raceway.
Click to expand...
But if enclosed only in a sleeve or chase, would the wire then be considered as directly buried???
 
Smart $ said:
...

If they do go with flexible cable for the underground portion, as long as the conduit is not terminated at either end, it is being used as a sleeve or chase, not as a raceway.
Click to expand...
Second thought... if there is any cable termination between small building and moving room, I don't see how it could qualify under uses permitted [400.7].
 
Smart $ said:
Second thought... if there is any cable termination between small building and moving room, I don't see how it could qualify under uses permitted [400.7].
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I am not presently planning on any termination between the junction box within the small building and the branch circuit panel within the moving room. This qualifies under 400.7(9), as I said at the beginning. What I worry about is whether it is disqualified under 400.8(6).

 
charlie b said:
I am not presently planning on any termination between the junction box within the small building and the branch circuit panel within the moving room. This qualifies under 400.7(9), as I said at the beginning.
Click to expand...
Just covering possibilities. Early on you mentioned cable reel as a possibility. If secured to the moving room, no issue. If reel is at the stationary end, then you'd have a termination in between.

What I worry about is whether it is disqualified under 400.8(6).
Click to expand...
I gave you the out. If the intent is to install conduit complete as a raceway, I don't know of any section which would except 400.8(6).
 
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