Neutrals

Guardsman

Member
Location
Midlothian VA
I have been trying to explain to a coworker how the neutral is the return path of the current in a electrical circuit. This all started when I told him even when he shuts off the main breaker in his panel and fires up the ole generator he is putting power onto the neutral conductor entering his panel in turn which can zap a lineman doing his repair work. Can some please give me a simple example of why when neutrals and equipment grounds are together at service panel and the neutrals current does not makes his grounds hot ??? If you have ever stood in the middle of a field and talked to a rock you will understand what its like talking to my coworker
 

iwire

Moderator
Staff member
Location
Massachusetts
Welcome to the forum, let's work on things one at a time starting with this.

This all started when I told him even when he shuts off the main breaker in his panel and fires up the ole generator he is putting power onto the neutral conductor entering his panel in turn which can zap a lineman doing his repair work.
Actually that is false, if every thing is wired correctly and the main is open you cannot shock a lineman outside the home.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Welcome to the forum, let's work on things one at a time starting with this.



Actually that is false, if every thing is wired correctly and the main is open you cannot shock a lineman outside the home.
Totally agree, that is one of those urban myths, if everything is wired correctly, there is no issue.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
There are times when there are more than one path back to the source even on a service. Meter to Service diso with rmc conduit creates a parallel neutral path. I have always wondered how much current travels there. Now electricity will take all path but based on impedance most of the current will travel where there is less impedance.

Your example of a generator does not hold much weight since most transfer switches are still connected to the service neutral as the neutral is usually not switched. Apparently this must not be a big problem down stream.
 

iwire

Moderator
Staff member
Location
Massachusetts
Even with many parallel paths the current can only flow back to the source and for that to happen there must be a complete circuit. The open main breaks the complete circuit so no current can flow.
 

Guardsman

Member
Location
Midlothian VA
Welcome to the forum, let's work on things one at a time starting with this.



Actually that is false, if every thing is wired correctly and the main is open you cannot shock a lineman outside the home.
Does this still remain true if the panel is backfeed through a doublepole breaker ? There is no transfer switch... that is what he is doing
by way of wisdom of hardware store (electrican)
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Does this still remain true if the panel is backfeed through a doublepole breaker ? There is no transfer switch... that is what he is doing
by way of wisdom of hardware store (electrican)
I don't condone it but if the main is off there should not be an issue-- not everyone remembers to shut the main.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Does this still remain true if the panel is backfeed through a doublepole breaker ? There is no transfer switch... that is what he is doing
by way of wisdom of hardware store (electrican)
Yeah, we do a lot of hurricane duty, and I've been in the big box stores where their "Qualified" personnel have told customers to put male cord caps on the extension cord and plug it into the dryer outlet! Very dangerous practice.
 

iwire

Moderator
Staff member
Location
Massachusetts
Yeah, we do a lot of hurricane duty, and I've been in the big box stores where their "Qualified" personnel have told customers to put male cord caps on the extension cord and plug it into the dryer outlet! Very dangerous practice.
I was at a customers store during an outage and they showed me the 50 amp double ended cord they used to back feed a panel for the registers. They did have a decent double throw switch instaled so no back feed but just the double male cord was scary. We are correcting it.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
Does this still remain true if the panel is backfeed through a doublepole breaker ? There is no transfer switch... that is what he is doing by way of wisdom of hardware store (electrican)
Beware: The following is internet gossip from an engineer that has not had a paying job as an electrician for over thirty years.

Some panels have a clip (bracket, lock-out) available that prevents having both the main and the gen CB on at the same time. Most all panels have a clip (bracket, lock-out) that prevents two adjacent CB being on at the same. That is what I'm using at my house. It's on a small MLO subpanel for the critical circuits, two adjacent 2 pole 50A CBs. One fed from the main panel and one fed from the gen - both 4 wire. Meets code - works great - looks safe to me.

ice
 

jumper

Senior Member
Yeah, we do a lot of hurricane duty, and I've been in the big box stores where their "Qualified" personnel have told customers to put male cord caps on the extension cord and plug it into the dryer outlet! Very dangerous practice.
I was at a customers store during an outage and they showed me the 50 amp double ended cord they used to back feed a panel for the registers. They did have a decent double throw switch instaled so no back feed but just the double male cord was scary. We are correcting it.
Aren't those called "suicide cords?"
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I don't condone it but if the main is off there should not be an issue-- not everyone remembers to shut the main.
Leaving the main on is the issue or maybe not. How long would the generator run if the load were every house connected to the grid?
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Leaving the main on is the issue or maybe not. How long would the generator run if the load were every house connected to the grid?
Just long enough to kill a lineman. A couple of years ago a flatlander hooked their generator up through a "Suicide cable", did not turn off the main, and since the line was down a short ways down the road only a couple of houses were on it. The EMC'S lineman picked up what he thought was a dead line. I installed some transfer switches on a couple of chicken houses my friend took over. They had a range receptacle at the far end of the house to back feed the panel, one house they had it tied to a 50 amp breaker in the panel, but the other house they had it double lugged on the POCO side of the main.
 
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