NEC Allow Portable Power Cable Laid on Ground?

[dahtective17]

I'm reviewing a design for 600kW 480V portable generators being installed in a parking lot and connected to a building to allow parallel service with the existing utility connection to the building. The coupling between the utility and the generators is at a switchgear lineup outside of the building. There are many hoops and requirements that we are managing with the utility company to make this work, but an issue that I noticed is the contractor providing the generators would like to install 600V portable power cable on the asphalt/gravel between the generators and the switchgear. They would be installed for a period of 7 months before they will be removed.

How I'm reading NEC articles 400 and 590.4 (J), I don't see a way that it is permitted to route cables (even extra hard usage) on the ground like that. Am I missing something? I've seen it done before on generators, load banks, or other temp power solutions but I can't tell how the code permits it. NEC 2023 is in effect in this state.

 

[infinity]

How long is the run? Can you use a cable tray to support the cables?

 

[dahtective17]

Probably 150ft. I've told the contractors they need to provide cable supports and that laying them on the ground is unacceptable per code. They said they are going to talk to their engineering group and get back to me. I'm curious if anyone sees the code differently than I do because I've seen installation do it before.

 

[Dennis Alwon]

There is no way I would leave a 480v cable exposed like that esp. for 7 months. The least I would do is run some pvc underground and wire it safely.

 

[petersonra]

How is it not supported by the ground?

I would not do it because someone will run over it at some point if it is not protected.

Cable protectors?

Amazon.com : drive over cable protector

Bollards all around to reduce traffic incidents.

 

[dahtective17]

Thank you for the feedback. I don't think the ground is supporting it in place at intervals that ensure that the cables will be protected from physical damage. Plus the following statement in the code said support shall be in the form of staples, cable ties, straps, or similar type fittings installed so as not to cause damage.

 

[LarryFine]

RGS sleeving?

 

[Ken_S]

You can rent jersey barrier and hang the cables from it. I'm not sure what that will cost, and there's definitely a need for the right equipment to offload and set them.

 

[zbang]

How is it not supported by the ground?

It's very well supported , and running hard service cords along the ground is done all the time (not prohibited, ever see the back of a stadium during a rock concert? might see a 3-4' wide swath of 4/0 cables laid out).

I would not do it because someone will run over it at some point if it is not protected.

Jersey wall (aka k-rail) would work just fine; not hard to move with a Kenco grip and a telehandler.

OTOH, it may be cheaper to to pull thhn/etc into PVC.

 

[texie]

I'm reviewing a design for 600kW 480V portable generators being installed in a parking lot and connected to a building to allow parallel service with the existing utility connection to the building. The coupling between the utility and the generators is at a switchgear lineup outside of the building. There are many hoops and requirements that we are managing with the utility company to make this work, but an issue that I noticed is the contractor providing the generators would like to install 600V portable power cable on the asphalt/gravel between the generators and the switchgear. They would be installed for a period of 7 months before they will be removed.

How I'm reading NEC articles 400 and 590.4 (J), I don't see a way that it is permitted to route cables (even extra hard usage) on the ground like that. Am I missing something? I've seen it done before on generators, load banks, or other temp power solutions but I can't tell how the code permits it. NEC 2023 is in effect in this state.

This sounds like a real case for good engineering judgement and a discussion with the AHJ. My view would be that the genset(s) and all cabling should be properly fenced off so no one other than qualified people can get near near. If properly isolated in this manner I would be OK with running the cables on the ground.
Over the years I've done a fair mount of large temp power and each install presents it's safety challenges. We once did something similar to your situation where we ran about a 300 KW genset for house power to a residential high rise for about 2 months do to a catastrophic failure of service gear. My experience tells me that running large genset(s) in these situations 24/7 for months to an occupied building requires at lot of thought and baby sitting. The fueling is also an issue.
While I have done multi MW temp installs with parallel gensets, I have never done temp gensets in parallel with a POCO. That sounds like a real challenge.

 

[ActionDave]

All the temp power with generators I've done for concerts, events, or construction power has been cords on the ground. Put some orange safety fence up if you are really freaked out, that keeps all the badness away.

If you ever go to a gravel pit it's 480V cables run on the ground everywhere, none of it pretty, none it protected and a whole lot harsher environment.

 

[kwired]

All the temp power with generators I've done for concerts, events, or construction power has been cords on the ground. Put some orange safety fence up if you are really freaked out, that keeps all the badness away.

If you ever go to a gravel pit it's 480V cables run on the ground everywhere, none of it pretty, none it protected and a whole lot harsher environment.

Not subjected to exposure to general public either, but still need to keep it out of traffic areas if little to no additional protection.

 

[sgtsparky]

All the temp power with generators I've done for concerts, events, or construction power has been cords on the ground. Put some orange safety fence up if you are really freaked out, that keeps all the badness away.

If you ever go to a gravel pit it's 480V cables run on the ground everywhere, none of it pretty, none it protected and a whole lot harsher environment.

The gravel pit requires heavy cables MSHAW approved , over 90 days you would need approval by the AHJ. every 4 years I have to do load testing 4160, 2000Kw per gen, cables on the ground but blocked off so they can’t be driven over and you would not believe how many try to move barriers, (until we put up signs saying death may occur) but we do have cables on the ground.