Pulling a second 4KV Cable through Energized Manholes

[kosullivan]

We are considering pulling a new set of three individual 4KV - 750 MCM cables (1 per phase + a #2 ground wire) (1000+ feet) through a 30 year old spare conduit that passes through five existing buried 6 ft x 6 ft. pull boxes that have existing energized 4KV cables in several conduits running through them. We blew out the conduits with air and pull a 4" rat through all the conduits.

One member of the design team is saying that it is okay to pull through the pull boxes as long as we install insulated blankets around the energized conductors. Another member is saying that we need to fully de-energize / ground out all the existing energized conductors before entering the pull boxes. I am reading over NFPA 70E 130.xxx and 20 CFR 1910.333 trying to determine which method is OSHA appropriate.

I downloaded a "Pulling Calculator" from www.southwire.com and watched the www.Polywater.com pulling videos on You Tube (GREAT Info) but will pose the "pulling questions" in another question.

Any comments or suggestions would be appreciate.

Thank you for your time.

Kevin O.

 

[iwire]

What reason for not being able to shut down will be given to OSHA if an accident happens?

 

[GoldDigger]

What reason for not being able to shut down will be given to OSHA if an accident happens?

On the other hand, if the exposed conductor insulation is intact and you protect it from physical damage in the pull box, is this really hot work?
Pulling additional wires into the same conduit would be risky though.
Is it hot work to operate a lift near insulated (not just covered) live lines?

 

[iwire]

On the other hand, if the conductor insulation is intact and you protect it from physical damage in the pull box, is this really hot work?
Pulling additional wires into the same conduit would be risky though.

It does not sound like live work to me.

It does not change my question.

 

[zog]

Per the 70E just inspecting MV cables in a manhole while energized is HRC 4 arc flash and also requires insulated gloves. So pulling a cable would pose an even greater risk of arc flash and/or shock than just inspecting them wouldn't you think?

Insulated cable examination, in manhole or other confined space
HRC -4
Insulated gloves?- Y
Insulated tools? - N
Arc flash boundary - 420"

 

[kingpb]

I think a good question to ask ones self is:

If this situation presented itself to you,your kid, or grand kid, what safety precautions would you take, or be willing to overlook? Then envision something does go horribly wrong, could you live with yourself for putting them in that type of risk?

Proper safety while working in potentially life and death situations; is not an option.

Sadly, the only reason they do not want to de-energize is either $$$ or inconvenience.

 

[petersonra]

If I was not worried about the lives of my employees I might well be worried about the damage and down time that I might cause by doing the work with the power on.

 

[Ingenieur]

It could be done hot safely
ppe
roller/sheaves
barriers/blankets

but it would have to be a compelling reason to do so
preferable to do it during a planned or scheduled shutdown
should not take long if set-up properly

 

[topgone]

What counts much is whose butt will be kicked if the unexpected happens?
I'm inclined to follow our cardinal rule: "No job is too important and no service is so urgent that we can't take time to perform our work safely." Just me though!

 

[Fulthrotl]

We are considering pulling a new set of three individual 4KV - 750 MCM cables (1 per phase + a #2 ground wire) (1000+ feet) through a 30 year old spare conduit that passes through five existing buried 6 ft x 6 ft. pull boxes that have existing energized 4KV cables in several conduits running through them.

Any comments or suggestions would be appreciate.

Thank you for your time.

Kevin O.

my assumption is that you have a straight pull thru the substructures, and
aren't turning corners in the vaults, or having to pull stuff out of the hole,
and loop back into the vault.

assuming you are using appropriate PPE, i've put sheaves and other guides
in place so you could pull thru the vault without being inside it.

if this is 30 years old, is the duct pvc or transite? if the duct is asbestos composite,
that pull rope will be hazmat when you are done with it.... plan on using a rope you
won't mind throwing away afterwards.

if you have someone down in the substructure with a pail of lube during the pull,
you've gone pretty far out on a limb, with no easy way back if something goes amiss.

would you personally, in your levis, t shirt, and work boots, like to be standing on
the cables in the bottom of the substructure, in about 4" of water, with a pail of polywater,
slopping it on the cable when it starts to come out of the pipe into the vault?

actually, the water is your friend. consider it as your personal shorts and grounds on all the
conductors hot down there. if they are submerged, and aren't faulting, things are looking up.
however, if you are the unfortunate person to create a fault, then the water is not your friend.

even if you are in your power ventilated 100 calorie suit with 15 KV gloves on, then you are
down in a hole with a fire and explosion going on around you.

living the dream.......