Order to connect 120v wires

Jimmy80521

Member
Location
Nebraska
I started my apprenticeship in 1998, and have worked with many electricians but the other day I had a guy say that if you have to work on an energized circuit you should disconnect the neutral 1st, hot 2nd, then ground. I was always taught when putting it together you go ground, neutral, hot, and taking it apart hot, neutral, ground. Anyone else heard of the neutral first, or last in connection or disconnection of a circuit?
 

Buck Parrish

Senior Member
Location
NC & IN
I've heard them say take the neutral off first. But I agree with Rob.

The problem or confusion occurs when you have three phases using one neutral. But the other two hots are in another box feeding a room full of lights. That's the easiest way to take out an acoustical drop ceiling.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I've heard them say take the neutral off first. But I agree with Rob.

The problem or confusion occurs when you have three phases using one neutral. But the other two hots are in another box feeding a room full of lights. That's the easiest way to take out an acoustical drop ceiling.
And if they take out the ceiling you would hope that they survive. We had two electricians who worked for our company get injured from working on energized neutrals. Actually one didn't get hurt he got electrocuted working above a hung ceiling disconnecting a light fixture, the other surivived but is permanatly disabled. You don't want to open a neutral on an energized circuit.
 

Tulsa Electrician

Senior Member
Location
Tulsa
Occupation
Electrician
If in deed you have a netural and unhook it first bad things can happen.

Even you unhook the ungrounded conductors first. Slap a amp clamp on that netural before unhooking it.
 

ammklq143

Senior Member
I always disco the energized conductor first and reconnect it last so you don't have a potential shock hazard with the neutral.
 

Jimmy80521

Member
Location
Nebraska
I couldn't agree with all of you more. I thought it was really odd. The guys started his apprenticeship 4 years before me. He must have been taught wrong and never questioned it.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Wv Master “lectrician”
I couldn't agree with all of you more. I thought it was really odd. The guys started his apprenticeship 4 years before me. He must have been taught wrong and never questioned it.
I’ve made the mistake of working on an opened up neutral on an energized circuit.
Explain to him that you become the next load in series if you come into contact with open neutral.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Sounds to me like something learned in the automotive world then misapplied.

I was taught when working with a car battery you disconnect the negative battery connection first and reconnect it last. This applied to negative grounded cars.

The idea was to avoid working on the positive terminal surrounded by chassis metal already connected to the negative terminal.

Jon
 

brantmacga

Señor Member
Location
Georgia
Occupation
Electrical Monke
The worst shock of my life, the one where I actually thought I was going to die, was from a neutral wire.

In an attic alone, working on tapping into a receptacle circuit to add a new drop; turned the breaker off, confirmed off with my meter, when I got to opening the neutral I had one wire in the left hand and one in the right and it locked me down completely. I was leaning over while working and my body weight pulled me off it as I fell into the ceiling joists. Seemed like an eternity and I thought about my kid on the way down.

Anyway. Someone crossed something up downstream (this was not a MWBC, 12/2), and the neutral I took apart was carrying the load of the 1.5HP pool pump.

Always check for neutral current since that event.


Sent from my iPhone using Tapatalk
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Sounds to me like something learned in the automotive world then misapplied.

I was taught when working with a car battery you disconnect the negative battery connection first and reconnect it last. This applied to negative grounded cars.

The idea was to avoid working on the positive terminal surrounded by chassis metal already connected to the negative terminal.

Jon
Also applies to DC solar connections.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
... I was taught when working with a car battery you disconnect the negative battery connection first and reconnect it last. This applied to negative grounded cars. ...

I prefer to phrase it as "disconnect the grounded battery connection first .... "

It prevents a problem when someone's working on an (admittedly scarce) positive-ground vehicle, but more importantly, it makes the rationale underlying the rule easier to understand.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
I prefer to phrase it as "disconnect the grounded battery connection first .... "

It prevents a problem when someone's working on an (admittedly scarce) positive-ground vehicle, but more importantly, it makes the rationale underlying the rule easier to understand.
Yup. Positively grounded wasn't so scarce in solar if you worked with Sunpower a few years back.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
I have heard that grounding the positive side of a fixed installation can inhibit corrosion, and that it was common among analog telephone lines, but I never did understand electrochemistry thoroughly enough to understand why.
 
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