Mounting Crane Ductor Bar to handrail on Dam

[electricaldoctor007]

I have a crane contractor who wants to mount brackets for Ductor Bar onto the handrail at my hydro dam. The previous Supt. stated this was acceptable.

When I took over this project, I learned of this and shut it down. 3 current carrying conductors and a ground. 575v @ 150amps.

I'm the new guy in a room filled with Mechanicals & Welders. I need some help. I can't seem to find the ammo I'm looking for in NEC.

Can someone provide some guidance?

 

[brantmacga]

Preface this by saying I have no experience with this application.


But I would think 368.12 applies, and 590.2.

Hopefully someone more familiar with this work will chime in.


Sent from my iPhone using Tapatalk

 

[tom baker]

This is some type of insulated bar. Is the bar fully insulated against shock? Is it typically mounted in the overhead where it is safe
Is there a section in the NEC crane article on this?
I don't recall seeing a crane question on this forum before?

 

[drcampbell]

"Duct-O-Bar"?

Conductor Bar Systems | Duct-O-Wire

ductowire.com

 

[winnie]

IMHO, don't delve through the code looking for a reason to reject this. If there is an obvious code prohibition, then of course you should heed it, but don't contort the code to prohibit something that you don't like.

If there isn't a code problem but your gut says 'this is wrong', then try to figure out why. Is it risk of someone touching live conductors? Sparking when the slide moves? Something else? Figure out what your true objection is, and then work with the rest of your team to address that issue.

Jon

 

[Eddie702]

Without seeing this it's hard to make a judgement but mounting "bussbars" on a "handrail" doesn't seem like a good idea

 

[electricaldoctor007]

"Duct-O-Bar"?

Conductor Bar Systems | Duct-O-Wire

ductowire.com

This the system the contractor is proposing. The mounting brackets will attach to the handrail (3" Carbon Steel Tube). The elevation would be 9' off the deck.
My concerns are quite obvious: 600v mounted to a handrail, 9' above the walkway, outside, in the Alabama heat.
I have a litany of horrors floating in head. Am I overreacting?

 

[electricaldoctor007]

IMHO, don't delve through the code looking for a reason to reject this. If there is an obvious code prohibition, then of course you should heed it, but don't contort the code to prohibit something that you don't like.

If there isn't a code problem but your gut says 'this is wrong', then try to figure out why. Is it risk of someone touching live conductors? Sparking when the slide moves? Something else? Figure out what your true objection is, and then work with the rest of your team to address that issue.

Jon

Thanks for your comments. Unfortunately, common sense is lacking. I'm dealing with a CM who's a welder and a Civil Engineer. Neither should be making a decision concerning electrical design. But they are. And electron chasers are despised.
I've pulled my STOP CARD too many times and been right. With them it's personal. I need additional help

 

[jim dungar]

How far will it be, horizontally and vertically, between the live bars and someone's hand on the hand rail? Is the hand rail bonded to ground?

Crane bus bar systems are regularly mounted to items that employees may be able to touch, like steel columns.

 

[GoldDigger]

Would it be all that much different if it were mounted at 9' or higher on a dedicated set of metal poles?
In that case, it would be much more difficult to make sure that the poles are effectively grounded, compared to the continuous metal handrail system.
The crane itself rolls on rails imbedded in the walkway/roadway adjacent to the handrail? Or are the rails on the non-access side of the handrail?
Is the walkway/roadway open to the public or restricted to dam workers?

 

[electricaldoctor007]

1. That was my recommendation to the contractor.
2. The rails are raised and are about 38" from the handrail.
The outside edge of the crane is approximately 20" from
the handrail.
3. The handrail is approximately 600' long.

 

[Jraef]

I did a lot of work on overhead cranes and bus systems for them in a manufacturing plant and a steel mill where the cranes were used 24/7. In our case, when riding in the “carrier” on the bridge crane, the bus bars were 7ft above my head, close enough to touch if I raised my hand. To be allowed on a carrier at all, you had to attend a 1 day safety training course, in which they taught you “don’t raise your hand”!

I’ve also done work in dams and IIRC the cranes are only used during maintenance work, which is done as a scheduled procedure etc. So the crane bus bars would not be energized all of the time, they would only energize them when a procedure was in process and only for as long as the crane was being used, possibly even sectionalized so that the bus rail was only energized where it needed to be. It’s also possible that the walkway would be locked out during the crane use for general safety reasons, which would mean only qualified workers would be allowed there during the procedure.

 

[winnie]

I think you want to look at NEC 110.27(a).

Arguably the way these are designed you don't actually have 'exposed live parts'.

Are these bus systems any more dangerous than a flexible cord of the same voltage and current?

-Jon

 

[tthh]

The other thing you can say is that the code is a minimum requirement and I am responsible for this facility and the safety therein and this installation is not acceptable.

 

[electricaldoctor007]

The other thing you can say is that the code is a minimum requirement and I am responsible for this facility and the safety therein and this installation is not acceptable.

I like that approach.

 

[electricaldoctor007]

I did a lot of work on overhead cranes and bus systems for them in a manufacturing plant and a steel mill where the cranes were used 24/7. In our case, when riding in the “carrier” on the bridge crane, the bus bars were 7ft above my head, close enough to touch if I raised my hand. To be allowed on a carrier at all, you had to attend a 1 day safety training course, in which they taught you “don’t raise your hand”!

I’ve also done work in dams and IIRC the cranes are only used during maintenance work, which is done as a scheduled procedure etc. So the crane bus bars would not be energized all of the time, they would only energize them when a procedure was in process and only for as long as the crane was being used, possibly even sectionalized so that the bus rail was only energized where it needed to be. It’s also possible that the walkway would be locked out during the crane use for general safety reasons, which would mean only qualified workers would be allowed there during the procedure.

You bring an interesting point of view! It's obvious you've done a crane or three. Using an administrative approach to mitigate the hazard is very practical.
Your approach allows me to be tactful, diplomatic, and still have my concerns positively received.

Between you and tthh I just may end up looking human. Not like a salty, old, Retired Navy Sailor. Bravo Zulu!!

 

[AKCraneGuy]

10 year OEM Overhead Crane field service guy gone independent here.
Code wise, I say there's nothing prohibiting this. 110.27 makes a good point which I'll reinforce.
I believe 610.21(A) addresses this. Shall be located or guarded in such a manner that persons cannot inadvertently touch energized parts.
The Duct-O-Wire and Conductix Wampfler bus bar products are marketed as 'finger safe', and I can attest to that. Those products are finger safe. Can someone accidentally stick a metal pole or object into the opening? Absolutely is could happen.
They also offer outdoor rated and high temperature rated products.
I know we're not talking about open-exposed conductors, but they are still aloud. 610.13(B)

Refer to NEC 610, OSHA 1910.179, ASME B30.2, B30.17, and CMAA (Crane Manufacturers of America)
All of which echo 610.21(A) or similar.

OSHA 1910.179 Overhead and Gantry Cranes
1910.179(g) Electric equipment
1910.179(g)(2) Equipment.
1910.179(g)(2)(i)
Electrical equipment shall be so located or enclosed that live parts will not be exposed to accidental contact under normal operating conditions.
1910.179(g)(2)(ii)
Electric equipment shall be protected from dirt, grease, oil, and moisture.
1910.179(g)(2)(iii)
Guards for live parts shall be substantial and so located that they cannot be accidentally deformed so as to make contact with the live parts.

ANSI / ASME B30.2 (2016) Overhead and Gantry Cranes
2-1.13: Electrical Equipment
2-1.13.2 Equipment
(a) Electrical equipment shall be located or enclosed so that, under normal operating conditions, energized parts will not be exposed to inadvertent contact.
(c) If guards are provided for energized parts, the guards shall be constructed or located so that they cannot be deformed, under normal operating conditions, to make inadvertent contact with energized parts.
2-1.13.7 Runway and Bridge Conductor System:
(a) Conductors of the open type, mounted on the crane runway beams or overhead crane, shall be so located or guarded that persons cannot inadvertently come into contact with the energized conductors under normal operating conditions or under maintenance procedures
as stated in para. 2-4.2.3.

Jraef makes several great points, administrative controls.
Sectionalized is a real thing in crane bus bar world and sounds like it could be a great option.
How much of the walkway is under the proposed runway conductor length? 100'? Perhaps go the extra mile like discussed and put up guards for the walkway length.
600' runway is likely too long to use a cable reel type system.
Other options could be: totally enclosed conductor rails/electrification systems, side entry bus bar opposed to the above pictured bottom entry type, and festoon cable system.