Pulling new wire/cables in conduit with existing 120V energized wire/cable.

[transman2]

Is it safe and legal per code to perform a push by with new cables in a conduit that has an existing energized cable.

 

[LarryFine]

I don't know, but I wouldn't want to if avoidable. Knowing the pull length, bends, termination spaces, etc., as well sizes of existing and new wires, room in conduit, etc., maybe.

How about using a non-metallic fish-tape or other pulling method?

 

[roger]

What's so important that it can't be turned off for a short period?

 

[BillyMac59]

If you must do it "live" , have your CYA policy in place. As applicable, get written approval from your superiors. A fibreglass (non-conductive) fish tape is called for. As others have mentioned, length of pull, number of bends, and conduit fill are all factors to be considered.

 

[transman2]

What's so important that it can't be turned off for a short period?

Funny you should ask but its at a nuclear plant and has been turned over to the owner but the contractor has been doing this as a norm but I recommend them contacting the owner for approval since its a safety related cable. The contractor tends to take short cuts so they don't have to deal with the owner or perform LOTO. Seems like there safety program is weak to me.

 

[Fred B]

NEC has nothing regarding pulling wire while wireway has live conductors in it. NFPA-70E and OSHA would have recommendations that might include as others said that not a good idea. Most hot work has very specific criteria to allow it including if to de-energize would create a greater risk or danger. Extreme care would be needed in performing such including care not to damage existing conductors.
Is there a reason that a new set of conduit can't be pulled rather than risk all the potential issues, including personal injury by using a live conduit?

 

[retirede]

Funny you should ask but its at a nuclear plant and has been turned over to the owner but the contractor has been doing this as a norm but I recommend them contacting the owner for approval since its a safety related cable. The contractor tends to take short cuts so they don't have to deal with the owner or perform LOTO. Seems like there safety program is weak to me.

I’d like to think a nuclear plant would have detailed safety procedures on performing every type of maintenance.

 

[n1ist]

If that circuit is so critical that they can't schedule a safe shutdown, what will happen if it faults out during the pull?

 

[infinity]

I don't know anything about the protocols at a nuke but in commercial work this is done all of the time. We usually pull out the EGC and use it to pull in the additional conductors (+new EGC) while the circuits are energized. Using an insulated EGC as a pull line for additional insulated conductors limits the possibly of damaging the existing conductors to near zero.,

 

[transman2]

I’d like to think a nuclear plant would have detailed safety procedures on performing every type of maintenance.

your right and I would have thought that to but they don't.

 

[transman2]

I don't know anything about the protocols at a nuke but in commercial work this is done all of the time. We usually pull out the EGC and use it to pull in the additional conductors (+new EGC) while the circuits are energized. Using an insulated EGC as a pull line for additional insulated conductors limits the possibly of damaging the existing conductors to near zero.,

Sorry but I would totally disagree with that procedure. Totally wrong and dangerous!

 

[infinity]

Sorry but I would totally disagree with that procedure. Totally wrong and dangerous!

Fair enough, you're entitled to your opinion but in 35+ years I've never had an incident while doing this. As I stated earlier this is a very common practice and I don't know of anyone who's ever had a problem in doing it either. It's not like we're jamming a 1/4" metal snake through a live raceway.

 

[RWC/NC.]

Transman2.. It appears in conversation, that your working a "hot facility". Don't know the location, nor into what "color" of your badge.
It's up to you, but I would be giving special consideration into what's divulged, (seen on or inside) regarding facility.

 

[Fred B]

I don't know anything about the protocols at a nuke but in commercial work this is done all of the time. We usually pull out the EGC and use it to pull in the additional conductors (+new EGC) while the circuits are energized. Using an insulated EGC as a pull line for additional insulated conductors limits the possibly of damaging the existing conductors to near zero.,

I haven't seen a conduit pull that the multiple conductors didn't have some level of entanglement and where pulling new didn't get semi jammed up with the twisted up existing wire. Not sure about live pulls but have done that sort of pull using an existing wire to pul in a new ones, but not always easy for reason mentioned. Haven't experienced any noticeable damage to existing wire so long as fill requirements met and lube is used.
So how are you maintaining the ground connections if you are using the ground wire as your pull string?

 

[infinity]

I haven't seen a conduit pull that the multiple conductors didn't have some level of entanglement and where pulling new didn't get semi jammed up with the twisted up existing wire. Not sure about live pulls but have done that sort of pull using an existing wire to pul in a new ones, but not always easy for reason mentioned. Haven't experienced any noticeable damage to existing wire so long as fill requirements met and lube is used.
So how are you maintaining the ground connections if you are using the ground wire as your pull string?

I should have mentioned that we only use stranded wire so even with #10 AWG there is no problem even when the raceway is approaching maximum fill. The EMT maintains the ground connection.

 

[oceanobob]

Was involved where we had done an install and the original pull was effortless and w/o issues. Some time later two conductors had to be added, during this recall musing what was the effect on the existing cables.....didnt appear to be a big deal as far as pull effort etc.

Years later (because some other equipment installation issues), we had to reroute that particular conduit, so in with a new and all new wires; determ the former and remove blah blah.

Crew got to looking at the insulation on that removed conduit and shu nuff there were signs of damage where one (or more) cable apparently continued to pass that same point on that existing wire. Interestingly one group pointed to that as a proof to not do the 'pull some more' technique while the c'est la vie folks said yeah but that scuffing / skiving was not really that bad.

~

I can see the contention described: one doesnt really know until after the second pull is done and then pull em all out to see if'n there was damage, which kind of defeats any savings of time.

 

[Greentagger]

All fun and games till you find a j box covered underground.

 

[mtnelect]

I don't know anything about the protocols at a nuke but in commercial work this is done all of the time. We usually pull out the EGC and use it to pull in the additional conductors (+new EGC) while the circuits are energized. Using an insulated EGC as a pull line for additional insulated conductors limits the possibly of damaging the existing conductors to near zero.,

Worked with a journeyman who had worked at San Onofre Nuclear Power Plant before it was decommissioned in 2013. They had a strict policy of not allowing standard wire strippers, only mechanical ones. They would have a daily check of all wiremen.

 

[drcampbell]

Funny you should ask but its at a nuclear plant ... The contractor tends to take short cuts ... Seems like their safety program is weak ...

Gives you a nice warm feeling inside, doesn't it?

 

[drcampbell]

... Interestingly one group pointed to that as a proof to not do the 'pull some more' technique while the c'est la vie folks said yeah but that scuffing / skiving was not really that bad. ...

Everybody knew it was an ill-advised shortcut, but they did it anyway. There was some damage, but it was not really that bad ...

Where have I heard that before?

https://www.gannett-cdn.com/presto/2021/01/28/NABJ/0a9d9907-5a92-4aa7-b0e6-d3ea1ff9d339-Challenger_01.jpg