New riser job question

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nickelec

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Hi all i recently scoped a job here in NYC to run a 100amp single phase riser in a high rise to the 12th story. After spending two or so hours trying to find the best route there isnt any easy options.the building was built probably in the 1910 1920s. The only way I see this to be possible is that there is a shaft that runs the entire height of the building for an exhaust duct. In theroy I could just throw down an MC riser cable as others have done but to me there seems to be an issue with support of this riser as there is no access on individual floors. From an nec stand point what does the code say about this any reference would be appreciated. The other option is corring through 13 stories.!!! And I don't want to do this lol .

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330.30(D)(1) Type MC cable shall be permitted to be unsupported where the cable is fished between access points through concealed spaces in finished buildings or structures and supporting is impractical.

However, 12 stories is a lot of weight pulling on the conductors. I would suggest attaching the 12 stories of cable to a wire rope at frequent intervals with wire ties (every 2 feet?) and lowering the combination through the duct. Strongly anchor the wire rope at the top and bottom of the duct. You would have to verify how much weight that would all be and make sure the rope is capable of supporting that much weight.
 
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Is there actually a duct installed in the space or is the space the duct ?
My first concern would be 300.22

Second concern would be 300.19
 
Coppersmith said:
330.30(D)(1) Type MC cable shall be permitted to be unsupported where the cable is fished between access points through concealed spaces in finished buildings or structures and supporting is impractical.

However, 12 stories is a lot of weight pulling on the conductors. I would suggest attaching the 12 stories of cable to a wire rope at frequent intervals with wire ties (every 2 feet?) and lowering the combination through the duct. Strongly anchor the wire rope at the top and bottom of the duct. You would have to verify how much weight that would all be and make sure the rope is capable of supporting that much weight.
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That's not a bad idea maybe even a small steel wire rope at at 200 feet it shouldn't even be that expensive

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If the shaft were an "exhaust duct" and was not putting the air it contains back into the occupied space(s), is it still "environmental air handling space that 300.22 is addressing? I think a little reading between the lines is needed to say it is, though a little reading between the lines may also be needed to say it isn't. I think they intended this to apply to air being circulated into occupied spaces, exhaust air is no longer environmental air, any make up air is though.
 
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