# Question about back feeding



## randomkiller (Sep 28, 2007)

Exactly what is your trade? Ever hear of a multi wire branch circuit? You shouldn't be working hot to the switch.


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## Golden Arc (Apr 28, 2008)

randomkiller said:


> Exactly what is your trade? Ever hear of a multi wire branch circuit? You shouldn't be working hot to the switch.


Electricians helper. 

I dont think so. 

Im not working hot to the switch I turned all the switches off and hooked the light to the switch leg which is off. The neutral was hot and was causing the lights to go on and off.


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## randomkiller (Sep 28, 2007)

Tim Crimson said:


> Electricians helper.
> 
> I dont think so.
> 
> Im not working hot to the switch I turned all the switches off and hooked the light to the switch leg which is off. The neutral was hot and was causing the lights to go on and off.


 
Unless the breaker is off, your hot to the switch. A MWBC is more than one usually two ungrounded conductors sharing the same neutral. If your up on a ladder/scaffold and someone walks in the room, the first thing is to hit the light switch, which could be bad if the wire is in your hand at the time. To be safe at your level of the trade you need to kill all the breakers that feed these lights.


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## 480sparky (Sep 20, 2007)

I don't understand... the switch is turned off, so the lights are off, but the neutral is hot causing the lights to come on.


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## cmec (Feb 11, 2008)

If its 277 dont get seriesed in the neutral, Thats worse than a phase to ground


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## randomkiller (Sep 28, 2007)

480sparky said:


> I don't understand... the switch is turned off, so the lights are off, but the neutral is hot causing the lights to come on.


I took that as the neutral was feeding through the fixture he was working on and the connection was loose to the next fixture.


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## Golden Arc (Apr 28, 2008)

480sparky said:


> I don't understand... the switch is turned off, so the lights are off, but the neutral is hot causing the lights to come on.


Yeah, yes its 277 and there is no ground in the old wiring. The school is very old.


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## waco (Dec 10, 2007)

Might be a switchloop with the wrong (black) wire switched. I don't know if it has anything to do with being backfed (meaning the switch is supplied from connections at the fixture,) but it isn't unusual to encounter situations where the feed is at the switch and two wires go to the fixture, one through the switch. It could be the black wire which means turning the switch off breaks the path, but not the feed. You aren't supposed to switch the neutral.

I have encountered many instances where a switchloop's white wire is connected to the hot wire at the switchbox, but not taped to show it is a hot wire. I always tape the white wire when I make up a switchloop.

Assume nothing! Fact is, I just got zapped the other day by a hot white wire, part of the switchloop to the fixture. My fault. I put my "barker" on it and assumed it was barking at some low, stray voltage. It wasn't.


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## Golden Arc (Apr 28, 2008)

randomkiller said:


> Unless the breaker is off, your hot to the switch. A MWBC is more than one usually two ungrounded conductors sharing the same neutral. If your up on a ladder/scaffold and someone walks in the room, the first thing is to hit the light switch, which could be bad if the wire is in your hand at the time. To be safe at your level of the trade you need to kill all the breakers that feed these lights.


Were not able to turn all the breakers off all the time because they are still having classes in the school. What is the difference in a MWBC and 3 hot conductors sharing the same neutral?


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## randomkiller (Sep 28, 2007)

waco said:


> Might be a switchloop with the wrong (black) wire switched. I don't know if it has anything to do with being backfed (meaning the switch is supplied from connections at the fixture,) but it isn't unusual to encounter situations where the feed is at the switch and two wires go to the fixture, one through the switch. It could be the black wire which means turning the switch off breaks the path, but not the feed. You aren't supposed to switch the neutral.
> 
> I have encountered many instances where a switchloop's white wire is connected to the hot wire at the switchbox, but not taped to show it is a hot wire. I always tape the white wire when I make up a switchloop.
> 
> Assume nothing! Fact is, I just got zapped the other day by a hot white wire, part of the switchloop to the fixture. My fault. I put my "barker" on it and assumed it was barking at some low, stray voltage. It wasn't.


 
The volume of the ticker I use gets louder as the voltage increases, lower than 90 and no sound.


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## waco (Dec 10, 2007)

What is it?


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## Golden Arc (Apr 28, 2008)

waco said:


> Might be a switchloop with the wrong (black) wire switched. I don't know if it has anything to do with being backfed (meaning the switch is supplied from connections at the fixture,) but it isn't unusual to encounter situations where the feed is at the switch and two wires go to the fixture, one through the switch. It could be the black wire which means turning the switch off breaks the path, but not the feed. You aren't supposed to switch the neutral.
> 
> I have encountered many instances where a switchloop's white wire is connected to the hot wire at the switchbox, but not taped to show it is a hot wire. I always tape the white wire when I make up a switchloop.
> 
> Assume nothing! Fact is, I just got zapped the other day by a hot white wire, part of the switchloop to the fixture. My fault. I put my "barker" on it and assumed it was barking at some low, stray voltage. It wasn't.


I dont think its a loop. There are two black wires going down to the switch I figured one was the hot and one was the switch leg.


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## waco (Dec 10, 2007)

It should be obvious if the feed is to the fixture or to the switch, but if the lights are on a MWBC and if the switch is on to one side, the neutral disconnected from the panel will have line voltage on it. Common hazard with MWBCs. The good part is that if you complete the circuit, you'll be in series with whatever load is still on, so you won't be dropping all the voltage.

Two black wires to the switch? Do they both connect to the switch? If they do, it is probably a backfed switchloop.


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## 480sparky (Sep 20, 2007)

I doubt there's any white wire being used as unidentified hots if it's 277v in a school. My money's on it being piped, not NM'd or MC'd.


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## waco (Dec 10, 2007)

I agree, but I didn't see that it was a 277 volt circuit. Doesn't matter, I bet you're right about it being piped.


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## chollapete (Apr 18, 2008)

Tim Crimson said:


> Were not able to turn all the breakers off all the time because they are still having classes in the school. What is the difference in a MWBC and 3 hot conductors sharing the same neutral?


Tim--You and I are at about the same level, so don't take my word as necessarily correct. If I'm wrong, I hope the guys here will correct me.

The difference between a MWBC and 3 hot conductors sharing the same neutral: 

A MWBC is frequently encountered in NM (Romex) wiring, which is not allowed in most commercial occupancies. It is just 12/3 w/Ground, or 14/3 w/Ground. 3-conductor nonmetallic cable (NM, or Rome) has two hots, one neutral and one ground. (The proper names are: "ungrounded conductor" for hot; "grounded conductor" for neutral; and "grounding conductor" for the ground--the bare or paper-only covered wire, which is also called the "equipment grounding conductor" or "EGC".)

A MWBC is properly connected at the breaker box so each of the hots is on a different leg of the service. In typical 240/120 Volt, 1 Phase service, the power company brings in two hots and one neutral. The two hots come from one phase of the three-phase transmission and distribution power. These two hots are at opposite polarity, which means this: the AC goes from +120 volts, through zero, down to -120 volts, back to zero and back up to +120 volts. But timing is important. One of the hots is always at -120 when the other one is at +120, and vise-versa. They are synchronized and opposite. Sine waves that are 180 degrees out of phase. Sparkies often will say these two hots are "phases", but don't confuse this with actual 3-phase service. In proper 3-phase service, there are three hot conductors, each one is a sine wave, and they are each 120 degrees out-of-phase with each other. To distinguish the two legs of 240/120 single-phase from proper three-phase, I call the two legs "polarities". Anyway, to get 240 volts at a receptacle, you connect the two hots, because it is 240 volts across them. To get 120 volts, you connect one hot and one neutral. 

So, to finish up what a MWBC is, when pulling homeruns in a dwelling using NM (Romex), sometimes you will pull a 12/3 or 14/3, because that gives you two hots sharing a single neutral. Each hot gets breakered separately at the panel. The neutral goes to the neutral bar and the ground to the ground bar. Now, here's the kicker. If you turn off the breaker to one of the hots, the other hot is still completing its circuit on the shared neutral. So, just because you have de-energized at the breaker, the shared neutral can still bite you, because if the other hot of the MWBC is still energized, this second hot will be energizing the shared neutral. The 2008 NEC addresses this by requiring that the two legs of a MWBC be breakered with a tied, or double-pole, breaker--one of those double breakers where both handles are connected together so they are always both on or both off. 

So, that is one way a neutral can still be hot. By the way, since you were de-energizing at the switch (i.e., turning the switch off to de-energize at the fixture), the circuit feeding that fixture would still be hot up to the switch--which is what Random was talking about.

Now, the difference between a MWBC and three hot conductors sharing a ground is the difference between what I wrote above and what is written below:

Three conductors sharing a ground sounds awfully like it could be three-phase, four-conductor service. There are different ways to connect this. One way is when three-phase service is provided and the phases are wye-connected with a neutral being brought from the center of the wye. Other ways were more common in older days, and you say this is an old building with old wiring, so this building may have a different type of connection. But, in any case, three hots and one neutral sounds like the three hot conductors of 3-phase service with a neutral being gotten somehow. (Corner-grounded delta was more common in the old days, and there is still a lot of it out there.)

If you have three-phase, four-conductor service, it's easy for the neutral to carry current to bite you. In a perfect world, all the loads will be evenly balanced across the three phases--but, in the real world, the neutral will carry the difference in loads across phases. So, if phase A has 12 amps, phase B has 8 amps and phase C has 2 amps, there will always be current in the neutral, since the three phases are not balanced in load. The exact numerical number is some kind of vector sum that I don't know how to do--but it will be much more than 10 milliamps, which is enough to hurt, or 50-100 milliamps, which is enough to kill. 

Anyway, hope that helps. You can always Google anything I didn't explain well enough. And, I hope the journeymen and masters here will correct any errors I made. 

Be safe out there, Tim. 

Peace out,
Mark T.


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## dawgs (Dec 1, 2007)

Dont you have a licensed journeyman on the job with you?


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## Golden Arc (Apr 28, 2008)

waco said:


> It should be obvious if the feed is to the fixture or to the switch, but if the lights are on a MWBC and if the switch is on to one side, the neutral disconnected from the panel will have line voltage on it. Common hazard with MWBCs. The good part is that if you complete the circuit, you'll be in series with whatever load is still on, so you won't be dropping all the voltage.
> 
> Two black wires to the switch? Do they both connect to the switch? If they do, it is probably a backfed switchloop.



There are two black wires going down to the switch in a pipe. One is the hot and one is the switch leg. When I turn off the light switch one of the blacks goes dead this one is the switch leg, this is the one im hooking to the whip that is going down to the light.


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## MechanicalDVR (Dec 29, 2007)

Tim Crimson said:


> Were not able to turn all the breakers off all the time because they are still having classes in the school. What is the difference in a MWBC and 3 hot conductors sharing the same neutral?


There isnt a difference. That is a multi wire branch circuit. Its a common practice in lighting as your doing. So what your saying is that you cant turn off the breakers for the light circuit your working on?


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## Golden Arc (Apr 28, 2008)

MechanicalDVR said:


> There isnt a difference. That is a multi wire branch circuit. Its a common practice in lighting as your doing. So what your saying is that you cant turn off the breakers for the light circuit your working on?



Yes you are right


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## MechanicalDVR (Dec 29, 2007)

Tim Crimson said:


> Yes you are right


 
Are you using a lock out on the switch?


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## Golden Arc (Apr 28, 2008)

MechanicalDVR said:


> Are you using a lock out on the switch?



No, its unsafe.


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## 480sparky (Sep 20, 2007)

Tim Crimson said:


> No, its unsafe.


Using LockOuts is unsafe? That's their sole purpose.... safety.


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## Golden Arc (Apr 28, 2008)

480sparky said:


> Using LockOuts is unsafe? That's their sole purpose.... safety.



Ha no. I meant I know its unsafe just a bad habit.


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## randomkiller (Sep 28, 2007)

Tim Crimson said:


> Ha no. I meant I know its unsafe just a bad habit.


 
Not using them is a bad habit and you aren't in the trade long enough to have developed habits, let alone bad ones. Learn now how to become an old electrician.


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## Louieb (Mar 19, 2007)

If you LIVE after getting smacked down with 277volts especially with the neutral you will never trust yourself ! never mind someone else,that all possible safeguards are in place.If the circuits can't be shut off and tagged then your untrained tail should not be working on this task.Thank goodness you asked the question,now do something about the answers given,PLEAAAAZZZ!


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## rdoan71 (Apr 20, 2008)

Sounds like a classic case of "I found a box with a neutral over here..." Hard telling what else is "sharing" the neutral.


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## iamtodd4160 (Apr 30, 2008)

I am a firm believer in if you are not fixing the problem you are part of it. I have only read a few posts but if you choose not to properly control energy and lock out/ tag out, natural selection may take over and you find yourself on the floor wondering what happened if you are lucky. do yourself and coworkers a favor and take care of the situation


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## Golden Arc (Apr 28, 2008)

Thought I would update. Come to find out the transformer wasnt bounded of course creating its own neutral.


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## brian john (Mar 11, 2007)

> If its 277 dint get series in the neutral, That's worse than a phase to ground


OK we need MYTHBUSTERS here, that is a misconception, wrong and not right.

1. That the system is 277 has nothing to do with it it would be the same at one volt -infinity, though YES higher voltage has higher risk..
2. The open grounded conductor/neutral shock is the same as a phase shock only usually more surprising.
3. When the grounded conductor/neutral is open the voltage (in this case) is 277, it is not a neutral at this point it is an ungrounded conductor.

This stuff ain't magic.


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## 5volts (Jan 11, 2008)

> 2. The open grounded conductor/neutral shock is the same as a phase shock only usually more surprising.


Unless you get in series with a 277 Volt ballast. That will produce an inductive kick. That ballst is being charged you will get hit with more than 277 Volts.


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## nick (Feb 14, 2008)

*backfeed*

i agree with brian , and p logix , if the neutral in the transformer is not grounded the voltage can be any voltage of that source , now i must say p logix is correct in meaning if you add up all the ballast which are like auto transformers on or off when you make a tap thats inductance the voltage can be high like real high it wants you as the ground , i hoped you have fixed the ground problem , but dont work anything hot ! id say your leadman or your company safety person should give you direction , if is hot turn it off. lock it out . i know what it is to be shocked just shut it off !be safe . this is a normal problem on 3 phase 277 volts you can get a backfeed on another circuit if the other phases or phase happens to be turned on thur another circuit common neutral load mostly ballast like your lighting that your working on, its a common issue it happens in your case to be even worse due to open or floating neutral . meaning that voltage can be 3 times what it normally is or it can be any voltage that is closet to ground high resistance or low resistance changes the voltage up or down , it needs a ground you become the path to ground ,or the circuit that is off it feeds thur to ground from any place it can find in your case a no ground conductor not installed is bad news .the ballast are series up meaning hot thur next ballast thur next ballast and next ballast ect , when you connect these up you get high voltage meaning autotransformer your adding windings .each one gives a add on voltage to that original 277 v you started with . a phase b phase c phase at any point in time a to c or b to a ,one is a return opposite in polarity to the next phase we just see 3 phase as a output a b c but they go on and off in rotation one at a time , just a example to help you , just think of a phase c phase alone hooked up to a single phase load 480 v one is hot one is not its a return to ground . chollapete did a nice job explaining it . that other connection , is a delta but its c phase center tap to ground but yours its not a delta you only get 240 volts a b c or 120 volts to neutral on c phase only the high legs is b phase thats 199 v and it depends on where your at in the usa . didnt mean to offend anyone just my thinking but main issue here is turn it off and tell your leadman , your not going to work it hot .


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## jfwfmt (Jul 5, 2008)

When we are replacing ballasts in schools and "can't" turn off the breaker, we wear "meterman's" (500 or 1000v) rubber gloves and safety glasses. The gloves provide protection from getting shocked by any weirdness in the circuits and the glasses protect your eyes in case of an accident. Meterman's gloves allow enough dexterity to remove and install wire nuts (even the little orange ones). We are also installing the new ballast disconnects whenever we replace a ballast. We avoid opening neutrals if at all possible.


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## worn kleins (Dec 13, 2007)

*A helper working on a hot circuit??*

I don't know what state you are working in, but it is illegal in some states to be working a circuit hot like that, especially when you are less qualified than a journeyman to be doing that work. I have known journeyman that are no longer on this earth from working 277 lighting circuits hot. ALL circuits can be turned off and locked out. If there is a class going on, too bad, turn it off. You could die from what you're doing.


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## brian john (Mar 11, 2007)

JFW I am being polite when I make these statements and am concerned for your HEALTH!

These statements tell me you have no business performing the work you are describing.



> "meterman's" (500 or 1000v) rubber gloves and safety glasses. The gloves provide protection from getting shocked


METERMAN's?????



> by any weirdness in the circuits


 NO SUCH THING



> and the glasses protect your eyes in case of an accident


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## jfwfmt (Jul 5, 2008)

I don't plan to start a big argument but:

1. I am a journeyman
1.5 I have my 10 hour OSHA card and understand the dangers of working circuits hot.
2. As public employees we are not covered by OSHA rules
3. Meterman's gloves is poco parlance for electrical rubber gloves rated for working at 500V or 1000V; 10000V or higher lineman's gloves
4. Are you suggesting when I am troubleshooting and need to read voltage and current on energized equipment, wearing rubber gloves ... I'm more safe than when I'm installing a ballast disconnect wearing the same gloves?

Just so I don't sound like macho man, cowboy electrician:
When I started this job it was a complete safety nightmare:
1. people worked circuits barehanded and hot to 480V
2. people opened neutrals on 120/208 and 277/480 MWBC and wondered why the magic smoke came out of things -- repeatedly
3. no body wore a hardhat in circumstances that clearly warranted one
4. no body did lockout/tagout
5. the lineman's rubber gloves had not been tested in about 5 years.

1. I got the other journeyman to turn off most circuits before working on them
2. I explained what caused the magic smoke to come out and and been instituting the marking of MWBCs. I'm about to start a handle tie campaign for MWBCs
3. I gave hardhat to my co worker and tried to lead by example.
4. You have no idea how branch circuits are screwed up here. Missing and inaccurate panel board directories. Branch circuit layout that I swear was done by Oranutangs (SP?) on crack, with branch circuits passing two panel boards to land in a third one two hallways away.
5. With great resistance from management I instituted a 6 month retest of gloves and replacement of failed ones.
6. Started doing lockout/tagout, bought my own locks. I've had building adminstrators order custodians to cut lockouts. Luckily the custodian was a UMWA member and to him there was no way.
7. our boss wants us to work a 120/208V 800A service we're installing hot, we're refusing. He wants us to drive ground rods in the vicinity of a 6" gas line without "miss utility" marking, we're refusing...


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## brian john (Mar 11, 2007)

jfwfmt said:


> I don't plan to start a big argument but:
> 
> 1. I am a journeyman
> 1.5 I have my 10 hour OSHA card and understand the dangers of working circuits hot.


Not here to argue either but your teminology sounded like a 1st year apprentice.

I.E. Wierdness, there is no wierdness in electrical distribution.



> 2. As public employees we are not covered by OSHA rules


No but the laws of physics still apply. DEATH IS DEATH



> 3. Meterman's gloves is poco parlance for electrical rubber gloves rated for working at 500V or 1000V; 10000V or higher lineman's gloves


Surely a local term, sounded as I said 1st year.



> 4. Are you suggesting when I am troubleshooting and need to read voltage and current on energized equipment, wearing rubber gloves ... I'm more safe than when I'm installing a ballast disconnect wearing the same gloves?


I do believe the percentages weigh on the side that you are safer measuring voltage than changing a ballast. Shocks from working on light fixtures and falling off ladders doing the same I would bet lead the list in causes of electrical injuries.


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## rlc3854 (Dec 30, 2007)

I am confused, OSHA is a mandated federal regulated set of safety and helath codes. These are miniums that each state and subdisvion must follow. Just like the NEC if adopted the miniums are followed but can be made more restrictive but not made less restrictive. Under CFR 1910.? I believe you can find the OSHA electrical safety orders. WV is still part of the good old USA isn't it?


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## randomkiller (Sep 28, 2007)

rlc3854 said:


> I am confused, OSHA is a mandated federal regulated set of safety and helath codes. These are miniums that each state and subdisvion must follow. Just like the NEC if adopted the miniums are followed but can be made more restrictive but not made less restrictive. Under CFR 1910.? I believe you can find the OSHA electrical safety orders. WV is still part of the good old USA isn't it?


Pretty close, P OSHA covers municiple workers (Firemen, cops, DPW, etc).


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## worn kleins (Dec 13, 2007)

*the bottom line...*

This thread started about a "helper" working on hot lighting circuits. This is an unacceptacle pratice being done for no legit reason. If you have to work like this, than the least you should do is have a journeyman doing the work with another journeyman standing by. I stand by the fact that there is never any legit reason why you can't turn off a lighting circuit. The 2008 code is requiring that these fixtures now must have a disconnecting means at each fixture. I would guess that this guys boss does not know that he can be held liable for this "helper" getting injured or killed, along with the owner of the company.


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## waco (Dec 10, 2007)

I agree. There really is no excuse for anybody working on hot circuits, especially those above 115 volts. Many, many old buildings are wired such that voltages cannot be eliminated to fixtures. I think they should be fixed.


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## jfwfmt (Jul 5, 2008)

Yes WV is part of USA but States and their subparts (counties, cities, & town) inherit lots of immunity from federal laws that apply to every one else. (Think states rights under the constitution) OSHA does not apply to state employees unless the state passes legislation to allow itself to come under the rules. School employees are only covered by asbestos laws through a US DOL adoption of the OSHA standards concerning asbestos. In WV government employees are covered by a WV OSHA commission, which has never adopted any rules, indeed has never met, and has never been funded. On the other hand, with a good attorney you could probably sue, after the accident, and get the jury to consider the OSHA rules as a reasonable standard of care.

Dreadful, ain't it?

/s/ Jim WIlliams


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## rlc3854 (Dec 30, 2007)

Jim, all I can say is WOW!! Is there any standards to which you receive any kind of safety training? What are the exceptable experience and training required to land a job working for a school district or other government agency?


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## jfwfmt (Jul 5, 2008)

*requirements to be a school board electrician*

Job titles are established by state law. There are two electrician titles: Electrician I which is apprentice level and Electrician II which is journeyman level. The state law requires that you pass a practical test and a written test. When I applied for the Electrician II position the test was to run some emt to boxes in specified locations and to wire outlets and 3-way lighting circuits. The written part was waived because the tester was my former Electrical Trade instructor and I had recently passed the state journeyman's test with a 94 (80 was passing).

In my county (but not all counties) the job description requires a state apprentice or state journeyman's license for I or II. We have mandatory asbestos training and mandatory "safety around bodily fluids" training. No specific safety training and no specific electrical training. We are required to have 18 hours of continuing education per year with the mandatory courses taking 4 - 6 hours per year. We've just made a deal with our supervisor and the asst. super. of schools that we can use the 12 to 14 other hours of ce for part of the IAEI seminars, rather than taking vacation as we have been required in the past.

I attend two 1-day IAEI seminars and one 3-day IAEI seminar each year on my own time and on my own nickel.


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