MAD for residential service drops

[Tony]

Look at your firefighter job. You get training about electrical hazards. I know you do because my son is a fireman/first responder. Your training doesn't say, stay away. What it does is tell you the hazards you may, and will run into and the dangers involved and what you do to prevent being hurt. Why can't we do that with arborists? But we don't, we just tell them to stay away.

I see your point but you are lumping all Arborist electrical hazards training into one unfair category. Just as you did earlier in the thread when you said all EHAT for arborists is based on fear. Again I understand your viewpoint, but caution about overgeneralization.

This is not to pick on you Shadowscape. It is a good opportunity to point out what does and does not make decent training, especially in the area of electrical hazards. I trust in your intellect to see the difference and appreciate in advance your tolerance of using your comments as an example.

Any training that only outlines the "how" without the "why" is at an awareness level only and serves a specific purpose. As you called it "stay away" training is appropriate for very new workers and or people incidentally involved where there is an electrical hazard. "Stay away" mitigates a hazard with minimal input if followed.

You are absolutely correct in surmising "Stay away" lacks in many respects. It is a very temporary solution for a specific reason.

When EHAT has not only a "how", but a "why" component then it can start to inform a worker about the nature of the hazards and allow for different methods to mitigate or eliminate them. This is how I have taught hundreds of single to multi-day EHAT courses over the last 20 years. (Hence, my sensitivity to overgeneralizations!!)

When it comes to selecting or evaluating training of electrical hazards there should be plenty of "How", there should also be an equal or greater amount of "Why" and a smattering of the legislation that binds it all together.

Too much "how" is only a band-aid. A poor one that won't work long, but may be necessary.

"Why" without "How" is an electrical engineering course!

Over-emphasis on legislation just muddles what can be a confusing topic for men and women in the field. While necessary, administrative controls are much like traffic cones. They should be used, they can direct behavior, but you should never count on one to stop a moving vehicle from hitting you.


Back to the service drop Insulation topic. Rest assured I have learned and will adapt my teaching and wording thanks to your and others' knowledge shared here. I will however still "preach" and practice the "avoid contact" approach distance for this voltage range. This is in the Z133 because as arborists we neither have nor are trained to have/use the necessary PPE to physically handle such lines.

We can debate why this is and if it should change. I look forward to the day an arborist crew regularly uses a proximity detector to test for the presence of voltage on a job site. Perhaps the use of appropriate PPE and techniques for handling with these wires should be in our training...

Respectfully,

Tony

 

[evo]

Great thread - does someone who knows something about this stuff (definitely not me . . . ) care to comment on how home gen sets scattered around the 'hood maybe can complicate things - even if a utility guy has turned off the "power" for work on a tree? I've anecdotally heard all sorts of blah, blah over the years. Appreciate real info . . .
Cheers

I was about to ask the same...

 

[evo]

Personally I'm with @Shadowscape 's perspective. Any arborist will come into contact with at least a house drop, eventually, and we should be trained on the proper way to do it. Yes we should avoid it and have little business messing with anything electric but its in our regular working environment.
In the 16 years I've been doing this I have made direct contact with numerous house drops, countless indirect contacts.. A small hand full of indirect contact with the primaries, all of those were accidental.
Never bit on the clock. I've had a few before I got into the industry, some entirely not predictable. The worst was when I was fishing with my dad as a kid. There was a white PVC pipe coming up from the river into some sort of facility with chainlink and barbed wire. I am guessing it was some kind of water pump transport pipe, and I had to cross over it. It was about 3' above the ground and in one motion I threw a leg over it and grabbed it with both hands. Couldn't let go as I was being zapped and eventually my body went limp and I fell off of it. Never lost consciousness...
Another really DUMB thing when I was a kid, I was re routing the phone in my room, ran out of hands, and stuck the plugged in phone cord into my mouth.... Sometimes I do wonder how I made it this far into life.

 

[Shadowscape]

Personally I'm with @Shadowscape 's perspective. Any arborist will come into contact with at least a house drop, eventually, and we should be trained on the proper way to do it. Yes we should avoid it and have little business messing with anything electric but its in our regular working environment.
In the 16 years I've been doing this I have made direct contact with numerous house drops, countless indirect contacts.. A small hand full of indirect contact with the primaries, all of those were accidental.
Never bit on the clock. I've had a few before I got into the industry, some entirely not predictable. The worst was when I was fishing with my dad as a kid. There was a white PVC pipe coming up from the river into some sort of facility with chainlink and barbed wire. I am guessing it was some kind of water pump transport pipe, and I had to cross over it. It was about 3' above the ground and in one motion I threw a leg over it and grabbed it with both hands. Couldn't let go as I was being zapped and eventually my body went limp and I fell off of it. Never lost consciousness...
Another really DUMB thing when I was a kid, I was re routing the phone in my room, ran out of hands, and stuck the plugged in phone cord into my mouth.... Sometimes I do wonder how I made it this far into life.

Ever put your tongue on the terminals of a 9 volt battery? The phone cord buzzed you about the same way. Won't do any harm other than make you go, Uuuuuuuu!
I was visiting a friend who lives on an island this spring. The electrical line that runs to his house comes from a cable laid on the bottom of the lake and it comes up out of the water next to his dock. Probably was laid sometime in the 40s or 50s. The insulation was all cracked and broken off in spots. As his kids often swim off of and near the dock, I mentioned to him that I would be very concerned. He said he was going to contact the power company that owns the line and let them know. I hope he did.

 

[Shadowscape]

I was about to ask the same...

Were all your questions answered?

 

[Shadowscape]

I look forward to the day an arborist crew regularly uses a proximity detector to test for the presence of voltage on a job site. Perhaps the use of appropriate PPE and techniques for handling with these wires should be in our training...

Respectfully,

Tony

To that, I agree.

"This is in the Z133 because as arborists we neither have nor are trained to have/use the necessary PPE to physically handle such lines."
As an arborist the only realistic handling of service drops is, 1) The need to know nothing is going to happen if you accidently bump into one when up in a tree. 2) They can lift one up with their fiberglass pole to get equipment under it if they need to. 3) If they drop a small branch on it, it is not going to burst into flames and cause a problem. 4) Don't let your equipment contact the line, or any other conductive item.
That training is pretty simple and is better than making them scared of service drops by telling them to stay away.

Stay away from downed service drops. Stay away from arcing or damaged service drops. That part I would go along with. But I once again return to the lamp cord in your house. Same voltage. Same hazard.
A broken insulation on any 120 volt line can arc and cause a fire, such as the burning tree scenario mentioned earlier. Arcs are hot (as in temperature), that is why houses burn down from wiring problems. But bumping into 120 volt service drop while in a tree, or 120 volt service drop lifted with a fiberglass pole is not dangerous.

Tony, I understand the position you are in. You are governed by the rules laid down. I just think the rules need to be geared toward what is going to happen in the real world, and that is, arborists are going to try and lift service drops to get their equipment under; they are going to drop limbs on service drops; and they are going to be working in trees with service drops running through them. Z133 can say whatever, but we know what is going to happen in the field, and these people need to know that they can do their job safely. It doesn't take a 40 hour course to explain this.

Not arguing with you at all, just stating my view. Shoot, my kids never listened to me, why should anyone else.
I think I have beat this dead horse long enough.

 

[Stumpsprouts]

But I once again return to the lamp cord in your house. Same voltage. Same hazard.

I was wondering this last night.
When the lamp is plugged into a circuit running off a 15amp breaker, what does that do to the voltage? It stays the same?

Really appreciate all the contributions on this thread!

 

[Shadowscape]

I was wondering this last night.
When the lamp is plugged into a circuit running off a 15amp breaker, what does that do to the voltage? It stays the same?

Really appreciate all the contributions on this thread!

Yes. The voltage does not change. There is 120 volts going to your lamp.
The only thing the 15 amp breaker does is limit the amperage going to that circuit (however many outlets and lights are connected to the same circuit) to 15 amp draw. If it exceeds that draw, the breaker trips to prevent the wiring from getting too hot. Current creates heat. If something on that circuit shorts out, such as a hot to ground, or hot to neutral, the current draw skyrockets up and the breaker will trip. Also if you have too many things operating on the circuit and their combined current draw is higher than 15 amps it will trip. We see that in kitchens a lot when you are running the microwave and pop down the handle on your toaster and the circuit breaker trips. Too much current draw because the combined draw from the microwave and toaster were more than the breaker was rated for. The breakers are there to protect the wires, which are rated for only certain current. Example for residential wiring is 14 ga wire needs a 15 amp breaker; 12 ga wire can handle a 20 amp breaker; and 10 ga wire can handle 30 amp breaker. Commercial wiring has a stricter regulation. No matter, you still have 120 volts to your lamp.

So why do some things run on 240 volts? Remember volts is like water pressure. The amperage is like the water. If we double the pressure (voltage) we can cut the amperage draw. If you look at a motor that can be wired for either 120 or 240 (220) and look at the amps next to the voltages on the tag on the motor you will see that at 120 volts the amps might be 13, and next to the 240 volts it will say 6.7 amps. Those are examples only. Comes into play with motors that draw higher currents most often. Larger horsepower electric motors. As in, if I buy a wood planer for my shop and it has a 3 hp motor. If I want to operate that on 110 volts (120) it is going to draw 37 amps. I will need to run 8 ga wire to a receptacle that can handle 40 amps. Big expensive wire, expensive receptacle. By wiring it for 220 volts it will only draw 19 amps and I can run 12 ga wire and a relatively inexpensive receptacle. Actually you would want to run 10 ga to be code, but you get the idea.
220/240 doesn't have a neutral. You have two hots of different phases and a ground wire. Where your light has 1 hot going to it and a neutral coming back, the 220 has a hot going to it and a different hot coming back. Both have a ground wire in case of a fault (break in the system of to and from) so that the TO has some place to get back home and not go off in another direction trying to get there, like through you.

Does that also make it cheaper to run because it is drawing less current? No. Your electric companies power meter measures watts. Watts are simply, volts X amps. The watts end up being the same. Incandescent light bulbs use to be measured in watts, and people assumed that meant how bright they were, and for the most part that was true, but it really just told you how much energy it was going to use. Watts = volts X amps. 100 watt light bulb at 120 volts is going to draw (100 divided by 120) which equals, .833 amps. Now we use lumens to judge how bright bulbs are, which is what it should be, but confuses us older people.

 

[Shadowscape]

Which is probably more than you wanted to know.

 

[Shadowscape]

ouch!

 

[Tony]

As an arborist the only realistic handling of service drops is, 1) The need to know nothing is going to happen if you accidently bump into one when up in a tree. 2) They can lift one up with their fiberglass pole to get equipment under it if they need to. 3) If they drop a small branch on it, it is not going to burst into flames and cause a problem. 4) Don't let your equipment contact the line, or any other conductive item.
That training is pretty simple and is better than making them scared of service drops by telling them to stay away.

I agree here any any worthwhile EHAT program would address these things as you put them.

I know I do when I teach and when I train others to teach. I would add the caveat to all the above, “ with proper inspection”. I have seen triplex short and weld shit together when prodded, lifted and on one memorable occasion a hot and neutral crossed with a rope snap!

Thanks Shadowscape for a reasoned discussion. I have learned much and like you I lay down my stick. The horse is truly dead!

Tony

 

[Shadowscape]

I agree here any any worthwhile EHAT program would address these things as you put them.

I know I do when I teach and when I train others to teach. I would add the caveat to all the above, “ with proper inspection”. I have seen triplex short and weld shit together when prodded, lifted and on one memorable occasion a hot and neutral crossed with a rope snap!

Thanks Shadowscape for a reasoned discussion. I have learned much and like you I lay down my stick. The horse is truly dead!

Tony

Been a good conversation that I have enjoyed. Thank you for your input.

 

[Steve Connally]

No, we tend to be a bit more cautious as we age.
I was involved with propane explosions at a younger point in my life, and I sealed a room and flooded it with propane. Then I went in and lit a cigarette to prove a point that it would not blow up or catch fire to a class I was giving at the time. Propane UEL (Upper Explosive Limit) is 9.5% by volume, after that it does not explode.
Don't think I would do that these days. Besides, I quit smoke cigarettes 40 years ago..

Because you have to pass through the LEL and UEL in order to get to where you did what you did. The 20 year HAZMAT team veteran in me wants to point out that you may have done some dumb shit back in the day. LOL

 

[Shadowscape]

Because you have to pass through the LEL and UEL in order to get to where you did what you did. The 20 year HAZMAT team veteran in me wants to point out that you may have done some dumb shit back in the day. LOL

I did a lot of dumb shit in my 20s when I was invincible, and stupid.

 

[ghostice]

"I was involved with propane explosions at a younger point in my life, and I sealed a room and flooded it with propane. Then I went in and lit a cigarette to prove a point that it would not blow up or catch fire to a class I was giving at the time. Propane UEL (Upper Explosive Limit) is 9.5% by volume, after that it does not explode."

Might be of interest that at those levels, C1 to C3 can all begin to act as anaesthetic gasses. Link to a paper by Ian Drummond who, in riding the bus to work everyday with a friend who was an anaestheologist at a hospital in Calgary here, found that C1 to C3 (methane, ethane, propane) are all soluble in olive oil - one of the loose predictors of anaesthetic properties in humans apparently. The rest as they say is history. Another reason, besides Monday morning hangover, why some plant operators are sleepy at work . . . Cheers

 

[Shadowscape]

"I was involved with propane explosions at a younger point in my life, and I sealed a room and flooded it with propane. Then I went in and lit a cigarette to prove a point that it would not blow up or catch fire to a class I was giving at the time. Propane UEL (Upper Explosive Limit) is 9.5% by volume, after that it does not explode."

Might be of interest that at those levels, C1 to C3 can all begin to act as anaesthetic gasses. Link to a paper by Ian Drummond who, in riding the bus to work everyday with a friend who was an anaestheologist at a hospital in Calgary here, found that C1 to C3 (methane, ethane, propane) are all soluble in olive oil - one of the loose predictors of anaesthetic properties in humans apparently. The rest as they say is history. Another reason, besides Monday morning hangover, why some plant operators are sleepy at work . . . Cheers

Oddly, that experiment I stupidly performed was done at a fire academy. Thing were different in the early 70s.
Olive oil.... Thoughts are racing through my head.

 

[climbingmonkey24]

Interesting thread and highly productive conversation to have.

So how many here have routinely trimmed back branches within 10ft of a service drop with a non-conductive pole pruner, or rigged branches up and away from service drops from in the tree?

Me personally I will occasionally work near service drops and other utility lines, a few times I’ve even had the wires disconnected, but for all intents and purposes I stay clear of anything that would put me in too close of proximity of primary lines.

 

[colb]

That does include service drops, it also applies to communications lines, as they are also energized.

And also usually unknown, even though we "know"...

 

[evo]

Interesting thread and highly productive conversation to have.

So how many here have routinely trimmed back branches within 10ft of a service drop with a non-conductive pole pruner, or rigged branches up and away from service drops from in the tree?

Me personally I will occasionally work near service drops and other utility lines, a few times I’ve even had the wires disconnected, but for all intents and purposes I stay clear of anything that would put me in too close of proximity of primary lines.

Same here, but I’m also fairly quick to request a service drops if the line will slow us down.

It’s always good to have a good relationship with the power folks. I chat them up and do everything I can to help. Often they will hangout for a few while we jump on the tree, and they slap the power back up. Other times I’ll have them leave the line in place but just disconnect it as it aids as a visual placement for the clearance pruning.

There has been a few times where we did all the needed pruning and the other person shows up to reconnect it, and they find an alternate route to run the line rendering the pruning pointless!

Other times they just hack off the limbs and we clear the stubs and do the cleanup, never disconnecting.. kinda like a free bucket truck rental!

 

[Bart_]

Power distribution has another neat feature, inductance of the line. In brief, when you try to interrupt the current, the inductance kicks up the voltage to try to maintain the current flow. That's why substation interrupters are so fang dangled - dealing with the inductive arc. Inductance is your friend when you want an arc, like a welder. Welding and water - boogeyman!! (generally avoid) Unless you're welding a gas tank. Then there's power factor correction so less I is required to get PWR = VxI because there's actually a phase angle between the current and voltage and in phase is useful real power, out of phase just warms up your lines and enriches the power utility.

eyes glazing over yet

Do you figure the house drop transformer contributes significant inductance?

On the welding boogeyman, its 10's of volts but usually the 60 Hz or 120 Hz rectified so some heart and muscle concern is warranted. But the item is grounded so your sweaty welding glove is ok


In a storm cleanup situation All bets ought to be off as line crossing can occur somewhere you don't know. But if Wilber's tv and clock radio are fine and it isn't storm cleanup you can ratchet down your tenseness level.

For cheap arborists could be equipped with non contact line voltage sensors. Stick it on a pole, see how hot the line is - unless it's obviously sizzling and snapping. Live or unenergized for a start (?) Is there already such a lineman tool? I've got an indoor very close sensing tool but it's for bench top use.



Oh, and on inadvertently cutting the house drop line - it won't be a nice non-event like mowing your electric mower cord. Everything downstream of the panel is breaker and also sometimes GFCI protected so when a short fault occurs (overcurrent) it gets shut off (open circuited) presto. But the line coming from the pole has a lot more gumption and could deliver hundreds of amps into even just 120V to neutral and is intended to NOT shut off to my knowledge under heavy current - now that's about 5x normal weld arc and a dang high current knob setting (industrial!) so its gonna be a nasty big arc. So, faux pas!!!!!!!