Working on live ckts

[RatherBeFishin]

Curious if anyone does things differently when working on a live ckt.

I was taught in terms of the HOT wire, that it’s the “first to break” and “last to make” so disconnecting hot, neut, then ground.

And connecting ground, neutral , then hot

Or

with the GND wire in mind which really is the same exact thing,

It would be “last to break” and “first to make”

Found it interesting to know that a couple guys I know, when they’re feeling too lazy to find the breaker and changing a switch or outlet like hook the ground up last so when connecting the hot if it it hits the yoke on the device doesn’t arc and trip the ckt. I see the point but to me that’s the whole point that you want the ckt to trip and not have current go through you instead if you happen to be touching the grounded box, or your screwdriver comes in contact with the box, or your leaning on a ceiling grid, or leaning on building steel, etc

Wanted other sparkys feedback on the matter.

Disclaimer: we all know to find the circuit and never work hot under any circumstances is the right thing to do here. I’m sure we’re all guilty of not practicing this a time or two though lol

 

[James L]

I was taught in terms of the HOT wire, that it’s the “first to break” and “last to make” so disconnecting hot, neut, then ground.

And connecting ground, neutral , then hot

Or

with the GND wire in mind which really is the same exact thing,

It would be “last to break” and “first to make”

Absolutely. I teach it to any help, and try my best to practice it.

On very rare occasions I've inadvertently not followed it. Once got hung up on a 277v neutral in a grid ceiling. It's plagued me for the last 15 years wondering how I ever created an open neutral. It's not safe for humans or equipment

 

[RatherBeFishin]

Absolutely. I teach it to any help, and try my best to practice it.

On very rare occasions I've inadvertently not followed it. Once got hung up on a 277v neutral in a grid ceiling. It's plagued me for the last 15 years wondering how I ever created an open neutral. It's not safe for humans or equipment

I’ve been there myself, as a young cub. Prob shouldn’t have been put in the situation but was in a school and opened up a lighting ckt. Neutral splice first, not knowing any better and lights all went out and capped it back off quick enough to get the lights back on and didn’t get hurt. Valuable lesson though, I always warn apprentices always NEVER work hot but in the event you do someday, neutrals under a load and opened up can be quite an arc so always break your hot first. Or shed your load in a panel before taking off feeders, then neutral, then ground. Then say you didn’t hear that we never do those things wink wink lol

 

[Besoeker3]

But if you have to trouble shoot you have to deal with live circuits.

 

[letgomywago]

I've used the ground last method even when troubleshooting cheap toggle switches because of the chance it will hit the bare metal and pop the breaker. Working live does make things take longer and I use flat rate so I make more killing the circuit.

 

[electrofelon]

I was taught in terms of the HOT wire, that it’s the “first to break” and “last to make” so disconnecting hot, neut, then ground.

And connecting ground, neutral , then hot

Or

with the GND wire in mind which really is the same exact thing,

It would be “last to break” and “first to make”

I dont think you can generalize, its going to depend on the circumtances. For a device, I would remove the EGC first and make it back up last - unground that yoke so its not a shock or arc point. For something like a troffer I would cut and cap the hot, because if you cut the neutral first then you have to cut a second energized wire. Something like a service drop, its going to depend on where I am cutting it, the weight, working room etc. There is no best way for every situation.

 

[RatherBeFishin]

I've used the ground last method even when troubleshooting cheap toggle switches because of the chance it will hit the bare metal and pop the breaker. Working live does make things take longer and I use flat rate so I make more killing the circuit.

You mean when you’re disconnecting a hot wire off a switch you leave the ground on til last for safety right? Like it’ll hit the yoke connected to ground and trip the ckt instead of potentially shocking you and then you have to reset the breaker and bang em for a bit longer and more $ lol? I’m not judging just wanted to make sure I understood ya right @letgomywago

 

[letgomywago]

You mean when you’re disconnecting a hot wire off a switch you leave the ground on til last for safety right? Like it’ll hit the yoke connected to ground and trip the ckt instead of potentially shocking you and then you have to reset the breaker and bang em for a bit longer and more $ lol? I’m not judging just wanted to make sure I understood ya right @letgomywago

I take the ground off and pull them away from switches like say you have a 4 gang of miss wired switches you open it up and are likely to touch a switch to another's screw so i keep them as separate from a potential short as possible. You're wearing gloves right even cheap ones will keep you safe although not to legit safe it's better than getting sprayed with molten copper. If the the gloves aren't enough and it scares you then you're stuck working dead like you're supposed to anyway.

 

[RatherBeFishin]

Seems to be everyone has a method they prefer. I get hooking up ground last so as not to inadvertently touch hot to the yoke and have an arc and trip the breaker. Of course if you’re grounded anywhere the path will be through you now instead of that ground wire if it were hooked up.

Hooking up ground first is the safer method in my eyes as a hot contacting the yoke or box accidentally the circuit will trip and electricity would choose that grounding conductor over you instead. Even in that split second unless your drenched in sweat maybe the ckt would trip I believe before you felt anything.

Suppose the right answer would be shutting the ckt off!!

 

[LarryFine]

Seems to be everyone has a method they prefer. I get hooking up ground last so as not to inadvertently touch hot to the yoke and have an arc and trip the breaker. Of course if you’re grounded anywhere the path will be through you now instead of that ground wire if it were hooked up.

If I "must" (separate discussion) connect a device while the circuit is hot, I also connect the hot conductor to its terminal first and the EGC last, especially with narrow-body 15a switches. Their screw terminals are particularly close to the metal yoke.

That way, I know where the hot is, I don't have to divide my attention, and I have control of it while connecting the rest of the wires. I don't risk getting shocked if the hot inadvertently touches the yoke because I always hold the yoke with my pliers.

I don't want a fault arcing in front of me even if I won't get a shock from it (which is itself debatable because half voltage (or more) could theoretically appear at the fault point).

 

[electrofelon]

Of course if you’re grounded anywhere the path will be through you now instead of that ground wire if it were hooked up.

Hooking up ground first is the safer method in my eyes as a hot contacting the yoke or box accidentally the circuit will trip and electricity would choose that grounding conductor over you instead. Even in that split second unless your drenched in sweat maybe the ckt would trip I believe before you felt anything.

I am not following this argument.

 

[jaggedben]

... Of course if you’re grounded anywhere the path will be through you now instead of that ground wire if it were hooked up.

If you're grounded anywhere then the path will be through you regardless of whether the EGC is hooked up to the device.

 

[LarryFine]

I am not following this argument.

He's saying that connecting the EGC first makes the breaker trip, as an EGC is intended to do, instead of shocking you if you're holding the yoke.

 

[jaggedben]

FWIW on DC PV circuits (can't just turn 'em off) I was taught to hook up the ungrounded conductor first so that it couldn't arc to grounded parts. Can't hook up the EGC last because it's under the panels. This was in the old days of 'functionally grounded' systems.

 

[LarryFine]

If you're grounded anywhere then the path will be through you regardless of whether the EGC is hooked up to the device.

I believe the thought is that the duration will be much less.

 

[LarryFine]

FWIW on DC PV circuits (can't just turn 'em off) I was taught to hook up the ungrounded conductor first so that it couldn't arc to grounded parts.

Sounds like the safer car-battery terminal re-connect method.

 

[jaggedben]

He's saying that connecting the EGC first makes the breaker trip, as an EGC is intended to do, instead of shocking you if you're holding the yoke.

I believe the thought is that the duration will be much less.

Yeah, I still don't follow. Neither of those things are true. Okay, in the first instance, if you're grounded to something else (not the yoke) and you energize the yoke with the hot, then if the yoke is already grounded you'll get an arc flash, and if the yoke is not yet grounded it will now shock you if you're holding it. In neither case can you count on a breaker tripping (although if there's a good GFCI then that's better).

 

[Little Bill]

Sounds like the safer car-battery terminal re-connect method.

I had to get a battery in a hurry once and stopped by Autozone. The boy that was installing my battery hooked up the ground first and had a ratchet handle a mile long. I stopped him and asked him to take the ground off and put the positive on first. I asked him if anyone ever explained about connecting batteries. He said they just showed him the tools and said to do it. After I explained the dangers of it to him he understood and was a little pale thinking about all the times he had escaped the danger!

 

[nizak]

I couldn't tell you the number of times I've shut off a circuit on a residential service call and have the owner say that's a waste of time , it's only 110 it will just poke you.
I usually reply it's actually 120 V and if your so knowledgable why am I here.

 

[rambojoe]

I remind the keyboard geniuses that 6 volts can kill. And wait for the response...