Disconnect ground first?

[Joethemechanic]

Performance of the spark plug is probably a reason they do it the way they do.

Yeah it is, I can't remember the details though, been a long time. I know you can get a random intermittent misfire under some operating conditions if you reverse the polarity. And they all operate pos ground, no matter if the car/truck/equipment of it is pos or neg ground. Even your farm tractor with it's magneto is running pos ground

 

[LarryFine]

I remember reading that a major reason for switching to negative ground was a better spark.

 

[Joethemechanic]

I remember reading that a major reason for switching to negative ground was a better spark.

I've heard theories about it. Some say with positive ground electrics and pos ground spark the battery voltage is additive. A lot of old timers insisted pos ground electrics reduced galvanic corrosion of the body and frame etc.. Ford was big on pos ground, GM was neg ground. Lots of heavy trucks could be ordered either way up through the 1970's. Just for standardization reasons I used to convert the pos ground trucks to neg ground. Not only that but the pos ground radios were really expensive by then. Radio shack sold one that could be used on either system and it was like 35 dollars, but it was mono and just am/fm. The stereos with the tape player were like 400 bucks. Cheaper to just change the alternator around and swap all the wires on the analog gauges. Later on LED lighting became common and if you hooked a pos ground tractor to a trailer with led lights, the lights didn't work.

It had to end up being standardized, and neg ground won

 

[Tommy1776]

What are your thoughts, if your in a situation where you have to work live, about disconnecting the ground from a receptacle first. Of course generally first to make, last to break and all that but If you’re holding the yoke in one hand and unscrewing the hot wire with a screwdriver in the other, ungrounding the yoke might lower the chance of current passing through the chest in the event of accidentally touching the hot terminal, it'd seek ground through feet or another path or maybe not at all if you yourself are ungrounded. Any thoughts on this approach? What other risks may be more likely to happen by disconnecting the ground first?

Why would anyone work on a hot receptacle circuit?

 

[qcroanoke]

So would you hook it back up, hot first?

Yes. Thats how I was taught.
Disconnect ground first then neutral then hot.
Reverse this for connecting.

 

[electrofelon]

Why would anyone work on a hot receptacle circuit?

1. Too lazy to go turn off the breaker
2. Dont know which breaker it is
3. Other things on circuit that cant be turned off at the moment
4. Maye need to figure out what is what in a multi gang switch box so sometimes it just easier to do it live
5. Sometimes it takes more time to go flip the breaker than the increased time to do it live.

I did probably a dozen switches, a dozen receps, and 8 dimmers hot today because i didnt want to turn off the lights for the tile guys who were grouting. The drive home was probably 100 times more dangerous than the hot work . Thats me. I wouldn't tell anyone to work hot.

 

[busman]

1. Too lazy to go turn off the breaker
2. Dont know which breaker it is
3. Other things on circuit that cant be turned off at the moment
4. Maye need to figure out what is what in a multi gang switch box so sometimes it just easier to do it live
5. Sometimes it takes more time to go flip the breaker than the increased time to do it live.

I did probably a dozen switches, a dozen receps, and 8 dimmers hot today because i didnt want to turn off the lights for the tile guys who were grouting. The drive home was probably 100 times more dangerous than the hot work . Thats me. I wouldn't tell anyone to work hot.

There are times when a receptacle has burnt up to the point where you cannot plug in a circuit tracer. In which case, the choices are pull it out hot and take the wires off to attach alligator clips or throw the main. Same thing for a switch that controls something that you cannot attach a tracer to, such as a hardwired disposer. I have done it for this reason a few times, but always wearing hot gloves.

Mark

 

[qcroanoke]

8 dimmers hot today

Can you change dimmers while hot now?
I know at one time that was asking to burn it up.
Have they changed?

 

[electrofelon]

Can you change dimmers while hot now?
I know at one time that was asking to burn it up.
Have they changed?

Never had a problem. But If theres a short on the load side it will kill the dimmer everytime.

 

[Joethemechanic]

1. Too lazy to go turn off the breaker

This is the reason I use