15KV insulated overhead cable - applying insulation sleeves from grounded platform

[K7JLJ]

I can not find anything that considers an insulated HV line when talking about approach boundaries.

Is it legal to install HV sleeves into energized 15KV lines from scaffolding with or without rated hot gloves?
I know for uninsulated a EWP would need to be used but does that apply to an insulated line?

Thanks.

 

[hbiss]

I would not consider a 15kv line insulated no matter what's on it.

-Hal

 

[petersonra]

if they are already insulated, why are you putting sleeves on them?

 

[K7JLJ]

To allow contractors to use scaffolding near them. It's for visibility and extra protection from accidental damage from contractor.

 

[zbang]

Who owns the lines and who's doing the work? A utility (under NESC) or a private owner?

 

[K7JLJ]

The lines are on and owned by the facility (paper mill) and the work is done by fulltime E&I employees (me) of the mill.

Private owner

 

[Hv&Lv]

The lines are on and owned by the facility (paper mill) and the work is done by fulltime E&I employees (me) of the mill.

Private owner

You say insulated... what exactly do you mean? Is it tree wire or actual 100-133% shielded insulated MV cable?

National Electric Safety Code (NESC) Rule 230D:
Covered conductors shall be considered bare conductors for all clearance requirements except that spacing between conductors... may be reduced below the requirements for open conductors... when the conductor covering provides sufficient dielectric strength to limit the likelihood of short circuit ...

 

[jim dungar]

Unless you are trained in 'bare handed' work, you need to be using the proper PPE and appropriate insulated tools. Have you been trained on open air medium voltage circuits?

Does your company require you to have an EWP to touch or move energized 480V insulated conductors?

 

[K7JLJ]

Yes. It usually 500mcm MV-105

Is there an online version of NESC or can you point me a reference showing where it would apply to a private owner?

I’m unfamiliar with it but have seen more than once on this forum someone say it’s for utilities not manufacturing plants.

Appreciate the quote, that’s the first I’ve seen like it.

My point of the question is that some of our guys think it’s ok to do this bare handed from a grounded structure. They have no line work experience, I have a few years in a Mine (MSHA) but am no old salt at it.

Common sense says to keep 2 insulation levels between you and MV or HV though.

I want to find something that can be referenced for a reliable method I want to write up.


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[K7JLJ]

Unless you are trained in 'bare handed' work, you need to be using the proper PPE and appropriate insulated tools. Have you been trained on open air medium voltage circuits?

Does your company require you to have an EWP to touch or move energized 480V insulated conductors?

No and no.

When I asked for a bucket truck rental, it was given to someone that would do it the way they always have. Most times without Hot gloves even though they are available.


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[zbang]

"We're always done it that way" must be the cause of many accidents (and I don't like using that word since they're seldom really accidental). They might get away with it a few times, but then there's a break in the insulation..... 'course, my take is that even if it is fully insulated, I'm still using the appropriate PPE (but since I'm not MV trained anyway, I'm not going near the lines).

I don't think NESC ever applies to a private owner, but NFPA 70 and 70E would definitely.

 

[K7JLJ]

Agreed, but I find nothing in NEC or OSHA stating that "tree wire" or any insulated wire is ever considered as an "exposed" voltage potential that requires PPE. Nor anything that says insulated wire has any approach boundary.

From what I get out of the NEC it is considered a "guarded" potential and thus no PPE required. I'm hoping someone here knows differently?

SIDENOTE: I just asked our PE and it is believed that NESC does not apply to the plant, just the utility subs on the property.

 

[mkgrady]

I have never seen an overhead medium voltage wire that is insulated unless it was also shielded. I have seen Hendrix cable that has some form of covering but there is a reason they are always spaced apart. They are not meant to come into contact with ground or any other cable or peoples hands.

 

[K7JLJ]

MV-105 is shielded, does that somehow make it “protected and not considered live” for working on?

Reference?

 

[mkgrady]

Shielded MV cable is a different story. The shield is connected to ground. I don’t know what the safety rules are about touching it bare handed. We can’t even work inside a 120 volt panel live so I would imagine it is not allowed

 

[Hv&Lv]

MV-105 is shielded, does that somehow make it “protected and not considered live” for working on?

Reference?

Your PE is correct, NESC doesn’t apply to private plants. Doesn’t mean it isn’t a good recommendation though.

Try OSHA 1910.333

How close are they getting to the lines anyway?

 

[K7JLJ]

When we put the sleeves on we are touching bare handed or with gloves if the electrician wants to wear them.

The unauthorized workers using the scaffolding can get to 1 ft 1926.451(f)(6) with a blanket (sleeve) on a bare wire .

 

[K7JLJ]

1910.333(b)(1) | Occupational Safety and Health Administration

www.osha.gov

Application is “exposed” parts.

 

[jim dungar]

MV-105 is shielded, does that somehow make it “protected and not considered live” for working on?

Reference?

It may not be exposed, but it will always be live as long as it is energized.

 

[K7JLJ]

The wire behind the bucket door of a MV starter is the same and the approach boundary to the door is contact.

I have never seen a boundary determined off of something is live, only exposure potential.

The question of shielding has me wondering if this question because the shield is normally monitored for leakage and tied to a re-closure or something?