Changing breaker live

[busman]

Blowing something up or sparking something is not real world experience.

Oh really? What is it then. I began my career with B.S. and M.S. in Electrical Engineering, so I can do all the calculations you'd like (in fact I can derive the equations from the basic Physics equations if you'd like). I was just trying to give some examples of real world experiences with different incident energy levels.

I guess you haven't shown me the fault in my logic. Can you present a case where a service panelboard that accepts a 400A breaker is less of an arc-fault hazard than a 150A residential service (real world example)? I've never seen one.

Respectfully,

Mark

 

[claytazdaisy]

if you are not a trained electrician trained for EEW (energized electrical work) or have the proper EEW equipment you should not work in a live service.

 

[claytazdaisy]

not only mall management. security company. IT companies that provide support to all the individual servers. and any other utility that depends on eclectricity. so when you approach each vendor at the mall and tell them they will have to shut down their servers and then have their IT guy on stanby for the reboot. your talkin bout coordinating with 20 plus companies. or just go pick up the monkey suit and do work.
Ive been in this situation a few times doing TI jobs. and the vendors and property managment wont care about your saftey. just how much money they have to spend. there will be 5 guys that will just swap the breaker and be done with right behind the 1 that doesnt

 

[Karl H]

Oh really? What is it then. I began my career with B.S. and M.S. in Electrical Engineering, so I can do all the calculations you'd like (in fact I can derive the equations from the basic Physics equations if you'd like). I was just trying to give some examples of real world experiences with different incident energy levels.

I guess you haven't shown me the fault in my logic. Can you present a case where a service panelboard that accepts a 400A breaker is less of an arc-fault hazard than a 150A residential service (real world example)? I've never seen one.

Respectfully,

Mark

I think you and ZOG are mis-understanding one another. JMHO.

 

[zog]

Oh really? What is it then. I began my career with B.S. and M.S. in Electrical Engineering, so I can do all the calculations you'd like (in fact I can derive the equations from the basic Physics equations if you'd like). I was just trying to give some examples of real world experiences with different incident energy levels.

You gave no such examples.

I guess you haven't shown me the fault in my logic.

Because there is no logic in your examples.

Can you present a case where a service panelboard that accepts a 400A breaker is less of an arc-fault hazard than a 150A residential service (real world example)? I've never seen one.

Sure, 400A breaker in a panel with 20,000A available, protected by a breaker with a clearing time of 6 cycles at that level. 120,000 Amp-cycles or an Ei of around 4.08 cal/cm2@18".

150A breaker in a resi panel with only 5,000A available from the utility, protected by the fuses on the primary side of the pole mount transformer, so long clearing times for any fault on the secondary side, lets call it 0.5 seconds or 32.8 cal/cm2 @ 18".

Of course I could make those number be anything I want, because you dont seem to follow how an arc flash analysis is done, or maybe just are missing my point. The frame size of the breaker dosent mean squat.

 

[Twoskinsoneman]

Oh really? What is it then. I began my career with B.S. and M.S. in Electrical Engineering, so I can do all the calculations you'd like (in fact I can derive the equations from the basic Physics equations if you'd like).

Oh great here we go! Well let's whip em out and settle this so more deserving threads can get our attention...

 

[JWCELECTRIC]

not only mall management. security company. IT companies that provide support to all the individual servers. and any other utility that depends on eclectricity. so when you approach each vendor at the mall and tell them they will have to shut down their servers and then have their IT guy on stanby for the reboot. your talkin bout coordinating with 20 plus companies. or just go pick up the monkey suit and do work.
Ive been in this situation a few times doing TI jobs. and the vendors and property managment wont care about your saftey. just how much money they have to spend. there will be 5 guys that will just swap the breaker and be done with right behind the 1 that doesnt

Just tell them the power will be out for 15 min during routine generator test if one exists, If one does exist, then it's a good time to check that also with power off.

 

[busman]

You gave no such examples.


Because there is no logic in your examples.



Sure, 400A breaker in a panel with 20,000A available, protected by a breaker with a clearing time of 6 cycles at that level. 120,000 Amp-cycles or an Ei of around 4.08 cal/cm2@18".

150A breaker in a resi panel with only 5,000A available from the utility, protected by the fuses on the primary side of the pole mount transformer, so long clearing times for any fault on the secondary side, lets call it 0.5 seconds or 32.8 cal/cm2 @ 18".

Of course I could make those number be anything I want, because you dont seem to follow how an arc flash analysis is done, or maybe just are missing my point. The frame size of the breaker dosent mean squat.

Actually, I was very careful to mention a 400A breaker in a SERVICE PANEL. They are all protected by the utility primary. The 150A residential is going to be safer than the 800A commercial. I agree that a commercial sub-panel protected by a secondary breaker is safer, but that wasn't my example.

Respectfully,

Mark

 

[busman]

Sure, 400A breaker in a panel with 20,000A available, protected by a breaker with a clearing time of 6 cycles at that level. 120,000 Amp-cycles or an Ei of around 4.08 cal/cm2@18".

What 800A SERVICE PANEL is protected by a circuit breaker with 20 kA available fault current?

 

[claytazdaisy]

when a property managment company contracts work and each vendor will have to shill out a crapload of money to have their computers up and runnin by morning, your talking computer geeks charging $100+ an hour. those costs are not up to the managment company to cover. There will be a battle for a shut down. thats when your company loses the job.

i work for a very large electrical contracter that does very large jobs that have osha trailors onsite that have osha inspecters inside. Thats the trailer you sit it and recieve your ENERGIZED ELECTRICAL WORK certification, from OSHA. and osha requires that they are present for and hot work. plus my company has a ton of EEW suits. All the equipment that 1 would need to change a 400amp breaker in a hot panel and still make it home to your kids.

 

[claytazdaisy]

all while the GC, OSHA and your own boss watch over you

 

[claytazdaisy]

most of yall would probably crap a brick out sideways if anybody from AZ came on here and said " APS wont turn off service for a service change out, but they pulled the feeders out of the lugz and tapped em up real good for me. Is that safe?" thats standard practice out here

 

[220/221]

If you are nice to them, they might put on little rubber caps instead of just tape.

 

[e57]

I don't get it???? Boss not willing to buy donuts and coffee on a Sunday morning? Or is this really just someone over willing to shakey jake some bolts into place?

 

[busman]

Sorry if I was a bit grumpy last night. What I was trying to convey is that in the real world, some of us have to work things hot because the PoCo won't make it otherwise and there is no disconnect for us to pull. And of course the reality is - HOT WORK MUST BE DONE EVERY DAY. We just want to shift the risk to the lineman who aren't covered by OSHA. If I want a shutdown at an area served by underground distribution, there is no overhead cut-out to pull with a hot-stick. If I want the power off, a lineman can only open the transformer and disconnect the secondaries. Just because it's not me, doesn't mean I don't worry about the safety of the lineman too.

So yes, the calculations are good, and someday about 20 years from now, maybe half to three-quarters of the equipment will be marked with arc flash hazards based on calculations. In the mean-time, I'm just advocating that all personnel who work with electricity understand the principles of arc-flash so they can make judgements on the safety of a procedure. We need to develop that same intuitive fear of arc-flash that we have of heights.

So I'm not going to start getting scared when I test a 3-way switch for voltage. My gut will always get tight whenever I'm around anything that's only protected by the PoCo primary.

Just my opinion.

Mark

 

[cschmid]

nice thread and some nice input.

We are required to install quick disconnects on lights so they can be removed from live circuits safely. we install cord connected equipment daily so they can be disconnected from live circuits.

we deal with energized circuits daily and many times we do take chances and never even stop to think about the hazard, worst part maybe even dint know it.

When I use we that does not mean an inclusive blanket just a general statement. When I use live I am indicating a energized circuit. just to clarify the water cooler typing.

I change out lights almost daily and they are generally 277v. I have encountered many of these plastic disconnects installed before the code was required and they fail due to the heat involved when the ballast goes bad.

when you are replacing lets say a 400 amp breaker that means it has failed and that means the possibility of other problem really do exist. so you may have some variables you missed or even missed calculated.

So even installing and practicing all the safety precautions doing it hot is taking a chance regardless.

yet many properly trained electricians do it hot daily and some even think the gear makes them invincible.

yet is the greed of others worth the cash the job pays only you can answer that.

So all the rules and regulations only come into play when you make a bad choice. then your loved ones suffer as well.

so knowledge is our responsibility so if you dont know the hazards maybe you need more knowledge. we can learn from others so lets be a sponge and absorb.

 

[mcelweec@gmail.com]

we are trained professionals,working with electricity every day,assess the situation,sometimes it can be done live,sometimes it cant.its not a question of balls,but a question of good judgement.

 

[mivey]

To be honest: I have worked on live equipment. I have installed breakers live in panels. I just get a spidy-sense and the hair starts raising on the back of my neck when I get to a place where I feel there is a chance that I could get hurt and I take a different route.

Perhaps that is one of zog's point: the difference between perception and reality. I may have done things in the past I thought were safe but, through my own ignorance, was unaware of the danger level that may have been there.

To be honest on a second point: My spidy-sense is more likely to go off when working on the primary equipment or the secondary in an industrial plant than beyond the main breaker in a residential panel. I have been in industrial plants where I have seen the plant guys do some things that just made me step back...way back. You try to tell them, but you can't make people do things the way you would.

To be honest on a final point: I will work live equipment in the future, but I think my spidy-sense could use a tune-up.

Also, for the ones who felt intimidated to work something live: A good person will never force someone to do something they do not feel safe doing (even if it is just a freaky ladder situation and not live work).

 

[busman]

To be honest: I have worked on live equipment. I have installed breakers live in panels. I just get a spidy-sense and the hair starts raising on the back of my neck when I get to a place where I feel there is a chance that I could get hurt and I take a different route.

Perhaps that is one of zog's point: the difference between perception and reality. I may have done things in the past I thought were safe but, through my own ignorance, was unaware of the danger level that may have been there.

To be honest on a second point: My spidy-sense is more likely to go off when working on the primary equipment or the secondary in an industrial plant than beyond the main breaker in a residential panel. I have been in industrial plants where I have seen the plant guys do some things that just made me step back...way back. You try to tell them, but you can't make people do things the way you would.

To be honest on a final point: I will work live equipment in the future, but I think my spidy-sense could use a tune-up.

Also, for the ones who felt intimidated to work something live: A good person will never force someone to do something they do not feel safe doing (even if it is just a freaky ladder situation and not live work).

You hit the nail on the head. That's all I was after. Tuning up the spider sense. I'm going to put on the PPE to change a residential plug on breaker unless it's right on top of the transformer. I'm still going to pull meters. The PoCo won't do it reliably and if they DO show up, they just pull it bare handed. At least I'm going to protect myself a bit and do some checking before I reset it. It's a dangerous job, all the way around. Just feel it's better to understand.

Be safe everyone.

Mark

 

[KentAT]

i work for a very large electrical contracter that does very large jobs that have osha trailors onsite that have osha inspecters inside. Thats the trailer you sit it and recieve your ENERGIZED ELECTRICAL WORK certification, from OSHA. and osha requires that they are present for and hot work. plus my company has a ton of EEW suits. All the equipment that 1 would need to change a 400amp breaker in a hot panel and still make it home to your kids.

I am surprised and curious about OSHA's involvement in certifying workers for EEW. How does OSHA do this?

I cannot find any reference to this on OSHA's website or in their regs yet - still looking.


Kent