De-energized Panel?

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I had asked many questions and received great answers and now I want to post this thread that may save a life someday. Recently I added a main disconnect near the meter for an electrical panel on one side of a duplex apartment. The main breaker electrical panel was located upstairs in the unit. I killed the panel's main and the utility company pulled the meter. I went back upstairs and by habit checked the feeders to the main with my DMM. The feeders were de-energized. While attempting to separate the neutrals from the grounds in the panel, my hand touched between the ground bar and the bus bar and I received a hell of a jolt. Since my fingers were wrapped around a group of bare grounding conductors I found it hard to let go. I eventually did and I am fine, but further investigation showed that somewhere some wanna be electrician wired one branch circuit from the other unit to one branch circuit conductor from the panel I was working on and was being back fed through on OCPD to the bus bar that I touched.
Lesson: Even though the main is off, the meter is pulled, when working in a multi residential building (or any other building fed by more than one service) always check every branch circuit coming into the panel and/or the bus bar. Hope this helps somebody.
 

iwire

Moderator
Staff member
Location
Massachusetts
You bet, I got a good 120 VAC jolt while working in a de-energized 480 panel because some tied 120 and 277 branch circuits together.
 

charlie

Senior Member
Location
Indianapolis
While we are on this subject, assuming everything is disconnected and checks out as dead, do not open a path to earth ground without PPE and checking for voltage across the open point. If a neighbor has a bad or open neutral, his return current could be coming back through the metallic (you fill in the name gas, water, CATV shield, etc.) to find a return to the transformer. Keep in mind, if the serving electric utility disconnects the service, normally they will put 'boots' on the meter and the neutral is still connected. :smile:
 

steelersman

Senior Member
Location
Lake Ridge, VA
I had asked many questions and received great answers and now I want to post this thread that may save a life someday. Recently I added a main disconnect near the meter for an electrical panel on one side of a duplex apartment. The main breaker electrical panel was located upstairs in the unit. I killed the panel's main and the utility company pulled the meter. I went back upstairs and by habit checked the feeders to the main with my DMM. The feeders were de-energized. While attempting to separate the neutrals from the grounds in the panel, my hand touched between the ground bar and the bus bar and I received a hell of a jolt. Since my fingers were wrapped around a group of bare grounding conductors I found it hard to let go. I eventually did and I am fine, but further investigation showed that somewhere some wanna be electrician wired one branch circuit from the other unit to one branch circuit conductor from the panel I was working on and was being back fed through on OCPD to the bus bar that I touched.
Lesson: Even though the main is off, the meter is pulled, when working in a multi residential building (or any other building fed by more than one service) always check every branch circuit coming into the panel and/or the bus bar. Hope this helps somebody.
Thanks for the heads up. I would have done just like you and never would of thought about that.
 

mdshunk

Senior Member
Location
Right here.
One of my first days working as an electrician's helper was demo on a duplex. Our side was shut off. I blew up a nice pair of nines cutting out a receptacle. It was tapped off the neighbor's house. When the house was split into two units, they didn't divvy up the circuits properly between the two panels. A few strays in each unit were fed by the wrong panel.
 

iaov

Senior Member
Location
Rhinelander WI
I am always extremely cautious opening grounds or neutrals. Got bit in a panel as an apprentice opening a neutral that came from another cicuit not in my panel.
 

quogueelectric

Senior Member
Location
new york
I am always extremely cautious opening grounds or neutrals. Got bit in a panel as an apprentice opening a neutral that came from another cicuit not in my panel.
I got hit stripping a panel in a hospital in 1984 and never forgot since. Treat every conductor as if it is hot 24/7. Testing only takes a few seconds.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
Been there done that. Everything in the building disconnected from the panels and boom went the wires in the j-box when we went to cut them. Exterior lights being fed from a time clock in another building across the parking lot.
 
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only thing about that kind of tester is that static will set it off, it no sub for a good meter, it will warn you about potential voltage.
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
Try using an amp clamp before opening any neutrals.

Ya what he said, and this one works in tight places
k-1lg.jpg

http://www.testequipmentdepot.com/amprobe/voltage&continuity/k1.htm
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
None of those sniffers / tic tracers work on hot neutrals.
True, not until it's disconnected from the bus. But, as Bob pointed out, if it will shock you after it's disconnected, it will be carrying current before it is.
 

R Bob

Senior Member
Location
Chantilly, VA
While we are on this subject, assuming everything is disconnected and checks out as dead, do not open a path to earth ground without PPE and checking for voltage across the open point. If a neighbor has a bad or open neutral, his return current could be coming back through the metallic (you fill in the name gas, water, CATV shield, etc.) to find a return to the transformer. Keep in mind, if the serving electric utility disconnects the service, normally they will put 'boots' on the meter and the neutral is still connected. :smile:

A personal experience to reinforce your rule(which happens to be my rule now):
I was completing a service upgrade(meter pulled, no power) by reconnecting the ground from the TELCO NID to the GEC and got shocked. Voltage reading between TELCO ground and GEC=49volts.
I'm a believer!
 

dbuckley

Senior Member
Even if you sniff and measure before putting your hands in there, you can still get caught by misrouted neutrals. If theres a neutral from "somewhere else" that comes back to this place, when you measure, everything is dead. As soon as you seperate the neutrals, the one from "somewhere else" is now approximately a hot.

I got caught by this recently in, of all places, my own home, changing a wall light fixture. I became the return path for a CFL (thankfully) because some #$%^&*() sparkie in 1989 or there abouts couldn't be bothered running the wires correctly, and bootlegged a neutral (and did it badly to boot) behind a wall light fixture.

That was the first shock I'd got in years, and I was really angry (much blue air). And of course, this is in 240V land. Had that not been a CFL but a proper lamp(!) then that could have been me gone.
 
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