Work Inside Segregated 480 V Switchgear Rear

[joeking97]

We have a project where the contractors are wanting to run new cabling into a spare section of 480 V switchgear while the rest of the gear is energized. These are rear accessible where the horizontal bus and the adjacent vertical sections are isolated via solid metal panels. There is a vent section at the top of the panels separating the vertical sections. The vertical sections where work is occuring do not have any energized conductors. Although the work appears to be safe, I'm erring on the side of caution. I've been analyzing 70E and I think that we're not exactly following that. There are no exempted loads on this switchgear that would absolutely require the gear to be live. Would it be considered energized work because the rest of the gear is hot as the cubicle is part of an energized piece of equipment? Does the gap at the top precipitate an arc flash boundary? This is not a normal operating condition/operation (as the rear door would be open) so would that invoke the arc flash boundary?

Thanks.

 

[David Castor]

I think the best answer is obviously to de-energize the switchgear. If there are any exposed live part, it's definitely energized work. If you elect to do it energized, then PPE and insulated tools should definitely be used, imo. You'll need to do an arc-flash hazard assessment and determine the PPE required.

 

[petersonra]

It seems reasonably safe. The devil is always in the details though.

 

[jim dungar]

I was involved with a situation where contractors were pulling wires into a similar spare section. Somehow a washer moved, due to the equipment vibration, and shorted across some bussing. Luckily there were no injuries, just an unexpected 4 week loss of production while new gear was brought in. Forensics determined the washer was left behind during the original contractor installation.

Why can companies tolerate unplanned outages, but they can't deal with planned ones?

 

[joeking97]

I think the best answer is obviously to de-energize the switchgear. If there are any exposed live part, it's definitely energized work. If you elect to do it energized, then PPE and insulated tools should definitely be used, imo. You'll need to do an arc-flash hazard assessment and determine the PPE required.

I think so too. It's a pain in the butt, but at the same time I'd rather eliminate the potential for someone to be injured and/or equipment to be damaged. No one plans for an accident to happen. Plus you never know when gremlins are going to show up in your gear. The arc flash assessment that is present calls for a full cat 2 ppe loadout. My thinking and argument is not whether it is safe or unsafe to do while the bus is energized, but rather can the bus be energized? I argue that it should not be because elimination is the #1 item on the safety hierarchy and de-energizing does not create a more hazardous situation ergo non-exempt.

 

[joeking97]

I was involved with a situation where contractors were pulling wires into a similar spare section. Somehow a washer moved, due to the equipment vibration, and shorted across some bussing. Luckily there were no injuries, just an unexpected 4 week loss of production while new gear was brought in. Forensics determined the washer was left behind during the original contractor installation.

Why can companies tolerate unplanned outages, but they can't deal with planned ones?

Thanks Jim. I've been thinking about potential installation deficiencies too. Although it might work for a long time, it prematurely wears and you just happen to get in there at the wrong time that bad boy wants to fail. Vibration is a good point too, you get in there drilling holes and stepping on the roof of the gear (outside walk-in unit) and that could potentially jar something that's loose. I've also mentioned the potential of equipment damage causing a bigger downtime and that was taken with a little bit more consideration.

 

[joeking97]

It seems reasonably safe. The devil is always in the details though.

Yes sir. I had two gut reactions after I saw it - that seems safe enough, but it just doesn't feel right. I think it's enough of a risk to make me question it. Thanks.

 

[infinity]

If there are no live parts personally I wouldn't have a problem working in that section. As far as something coming loose or moving during the process there is an infinitesimal chance of that happening but it's not likely. Even if you de-energized and something did come loose you could be in for a big surprised when you re-energize and it blows up. We once had a service switch blow up when shutting off the one above it. A forensic investigate never was able to find why it exploded.

 

[letgomywago]

If there are no live parts personally I wouldn't have a problem working in that section. As far as something coming loose or moving during the process there is an infinitesimal chance of that happening but it's not likely. Even if you de-energized and something did come loose you could be in for a big surprised when you re-energize and it blows up. We once had a service switch blow up when shutting off the one above it. A forensic investigate never was able to find why it exploded.

But if they do a shut down and some bean counter says why did you do that they could atleast fall back on 70e to justify it and explain away the lost uptime. If an accident happened like the one mentioned above then you know that the same department at the company would try to regain those loses through the contractor who did the job live for them as a favor.

 

[petersonra]

But if they do a shut down and some bean counter says why did you do that they could atleast fall back on 70e to justify it and explain away the lost uptime. If an accident happened like the one mentioned above then you know that the same department at the company would try to regain those loses through the contractor who did the job live for them as a favor.

If someone leaves a tool in the switchgear and it somehow finds its way to a live part they will come after the contractor too.

You need to stop thinking of 70E as a crutch or a scapegoat and make decisions based on judgement and experience. If the situation makes you queasy, it is likely because you should find a different way.

 

[letgomywago]

If someone leaves a tool in the switchgear and it somehow finds its way to a live part they will come after the contractor too.

You need to stop thinking of 70E as a crutch or a scapegoat and make decisions based on judgement and experience. If the situation makes you queasy, it is likely because you should find a different way.

Yes a tool would cause that. Honestly there's many things that could cause this to be found to be the contractors fault. My point is that if someone were to make a mistake 40 years ago and no one knows and no investigation finds it but it was the cause how would the contractor who worked mostly safe be able to win the case that they weren't at fault. This is if they did nothing wrong other than not 100% following 70e but being close and the insurance for the building or the previous contractor using 70e as an industry standard for safety as a reason not to cover any injuries or whatever for the current contractor or their employees. There's also when an event like this takes place osha to deal with and it'll shut the place down if 70e isn't the written electrical safety program. Even if there is a separate better program written they still shut down the facility till they review the plan.

 

[jim dungar]

Yes a tool would cause that. Honestly there's many things that could cause this to be found to be the contractors fault. My point is that if someone were to make a mistake 40 years ago and no one knows and no investigation finds it but it was the cause how would the contractor who worked mostly safe be able to win the case that they weren't at fault. This is if they did nothing wrong other than not 100% following 70e but being close and the insurance for the building or the previous contractor using 70e as an industry standard for safety as a reason not to cover any injuries or whatever for the current contractor or their employees. There's also when an event like this takes place osha to deal with and it'll shut the place down if 70e isn't the written electrical safety program. Even if there is a separate better program written they still shut down the facility till they review the plan.

NFPA70E is not a 'how to' manual. It is a 'these are the rules' standard, just like the NEC is.

 

[letgomywago]

NFPA70E is not a 'how to' manual. It is a 'these are the rules' standard, just like the NEC is.

Of course but that's not how sleaze bag insurance will look at it.