I’m doing an exterior restoration on my 1905 Queen Anne. Sometime in the 70’s most of the exterior trimwork was removed and the building was covered in metal siding. I’m in the process of removing the metal siding, replacing the trimwork, and repairing the original wood siding.
The overhead power supply comes to a weatherhead mounted on the side of the house. I need to remove metal siding from the area around the weatherhead, then I’ll need to make various repairs to the woodwork, and then scrape, prime and paint. All of this is about 18′ off the ground, so I’ll be doing this work on ladders. The chances of making contact with the 220V,100A power line are good enough that I’ve got to assume it will happen, either through direct contact (which is pretty unlikely), or, more likely, indirect contact via a piece of tin siding, wood trim, or a paintbrush or some such thing.
How do you professionals deal with this situation? Is working on a non-conducting ladder sufficient protection from ground? Do you kill the power at the pole? Just do the job and not worry about it? I’ve been zapped by 220 once, and by 110 a few times (stupid mistakes when I was a youngster), and none of it killed me, but ignorance is definitely NOT bliss in this regard.
Replies
James
I don't know the answer to this but BE CAREFUL!!!
One tip, don't use an aluminum ladder.
Someone else will better answer this.
Doug
Oh, BTW, welcome to BT
generally, if I calll the power company, they send a guy who wraps it in a orange rubber blanket
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I love learning stuff like that. The discovery channel showed how to and not to get zapped by high voltage lines.
LOL, I'm wondering what their advice was on how TO get zapped.i've been part of two close calls - no , make that three, so I want to ad to my repetoire`
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I think that program was about lineman and HIGH voltage trasmission work, working off of helicopters, and wearing "corona "suits ...that kind of stuff, not residential distribution"
They used a visual aid to demonstrate how to get shocked. It was a man that had two claws instead of two hands. He had one hand grounded (I don't remember the details, maybe an aluminum ladder or siding) and his other hand hit something hot. It blew both of his hands off but he lived.
A plumber friend of mine, may he rest in peace, was in a crawl space (grounded) dragging an un protected drop light with him. The bulb broke and he made contact with the thin little wire that held the filament. It killed him.
The End, Jack
Sorry for your friend. It is a serious subject.
Not all events end up that bad, thank GodWhen I grew up, the lights in our bedroom were just a couple bulbs in porcelan sockets in the cieling.I had one top bunk, my brother Eric had the other. Kurt and Chris had the lower onesWe four boys learned a lot by experimenting and doing things. Kurt took apart every mechanical device in the house at one time or another. He put some of them back together...that's another story.Anyway, one day we heard this great big thump in the bedroom upstairs and the whole family ran up to check it out. Eric was dazed and just coming to. it seems that he got to wondering just what it was up inside that porcelan fixture that made the light come out of the bulb...So he unscrewed the bulb and when he couldn't see enough to satisfy himself, he stuck his thumb in. Next thing he knew, he was on the floor.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Thakk God!
Thanks for asking. Lots of this sort of problem going around.
First step would be to contact the power company. Explain the situation. Often they will come out and install an insulating rubber sleeve on the wires for you. Some will do it for free while others want a nominal fee for the service.
Using an insulated ladder, typically fiberglass, wouldn't hurt but if the aluminum cuts into the insulation and shorts against the neutral it is going to be dramatic. Bang, growling humm and a lot of sparks. That ladder might keep you from getting a shock but it likely won't keep you from falling.
In a pinch, no time for the POCO to come out, I have been known to install a guard made out of a 10' length of two inch PVC conduit. Use larger sizes for larger drops. I slit it up the side. A tablesaw does it fast and easy but a hacksaw will also work pretty well. Then I spread the conduit, helps to nick the other side slightly to form a hinge sometimes, and place it carefully on the drop. A few wraps of duct tape pull the edges shut and keep the conduit from inverting, and becoming a trough for rain, or sliding.
If you go this route, do try the POCO route first as they can do it quickly and safely, be very careful. Not unheard of for the insulation on a service drop to be cracked and brittle. Messing with it can cause an immediate, and very dramatic, short that only stops when it blows clear. Most aren't that bad. I sometimes use a pair of binoculars to inspect it before I work on it.
A middle course would be to contact a local electrical contractor and they can insulate, drop or arrange a guard around it. Won't be free but getting nasty or fatal shock or made to fall off a ladder can be expensive also.
What Piffin said but....
wear rubber underwear! bzzzzzzzzzzzzzzzzzzzzzzzzzzzzt!
Yeah, the guy holding the ladder for you will appreciate it.
Yep, best solution is to call the power co and have them wrap the wiring, though some are more responsive than others in this regard.
Be aware that there is a major difference in the amount of hazard, depending on the type of wiring. Newer wiring, where the three wires are twisted together and two of them have heavy plastic insulation, is much safer to work around than the old rubber/rag-covered stuff that comes in as three separate wires, usually with the insulation cracking and falling off.
That's not to say that either form is "safe", but with the old stuff the chance of an accidental contact leading to a jolt is about 50%, whereas with the new stuff the chance is probably less than 1%. With the new stuff the greatest hazard is usually at the splices where the overhead wire is joined to the wires that enter the house -- the insulation on these splices is often less than perfect. Otherwise the danger is an unseen cut or crack in the insulation, or having a piece of your sheet metal slice through the insulation.
"The chances of making contact with the 220V,100A power line "
That is not true. I am surprise that 4lorn1 did not clarify this.
That is NOT a 100 amp line.
If the hots short or one hot to the neutral that line will be carring several thousand amps, at least for a short time. There ain't no fuse on it.
(And being as anal as I am I will also tell you that it ain't 220 v either, more like 240).
Yeah, but only 120V to neutral.
Only? That's more than enough potential to drive a tenth of an amp through your body under most conditions. And that's plenty to stop your heart.
I'll second what Bill said, a residential drop is only indirectly fused (on the primary side of the transformer, and at 10,000 amps). So a direct short really creates fireworks.
Cliff
Bill, if you can find a municipal power supply that runs a steady 120 or 240 let me know. I use 110 and 220 because (1) I find those numbers more accurately match what I'm reading on my meter most of, but not all, the time (2) I just find them easier to remember for some reason and (3) everyone still knows what I'm talking about. Your point that I'd actually be facing, at least for an instant, nearly unlimited amperage, is a good one, though, that I hadn't though of. So it's a call to the power co. this morning for a safety wrap.
Thanks for the advice, everyone. I appreciate you all taking the time.
Now, on a side note. There are some seriously anal retentive, crotchety people on this board who seem to specialize in finding fault with everyone else's work. You know who you are (and I am definitely NOT going to name names), so go get a life.
Thanks again.
The design standard is 120/240 and seriously 110 would be too low.IIRC the design standard is 117/126 and outside that it is complaint time to the power company.However, there is an exception for California residents that allows it to go a little lower. They reduced the lower limit when they had there power shortage a couple of years ago.
I cannot dispute the correctness of that, Bill. My meter was ancient (before it crapped out altogether) and hadn't ever been calibrated in any way that I knew of. And I actually only played with voltage readings, was actually using it just to test for live and for continuity.
Re: "I am surprise that 4lorn1 did not clarify this. That is NOT a 100 amp line."Way I figured it the actual amperage available or the amperage involved in a shock or short wasn't really important. That it is more than enough to kill, cause a fall or fire is reason enough to avoid the situation if one doesn't know what is going on or be cautious if they do should be enough. Dead is dead. As you well know the available current in a service drop is limited primarily by the circuit impedance. Secondarily, at protracted currents in the thousands of amps at the secondary, by the fuse on the primary side of the transformer.The available short circuit current available at the service drop is likely measured in the thousands of amps for many seconds. This up against the simple fact that a single amp shot arm to arm for a fraction of a second is enough to stop a heart and a much smaller current capable of causing a fall. If the current doesn't burn the arms to a nub it can stop the heart and failing this snapping your neck in a fall is a popular way to go. Other than some sort of perverse bragging rights I'm not sure knowing that 2000 versus two amps caused the accident makes any difference. Any more than dying slipping on the soap in a tub or falling off a 1000' cliff makes any functional difference. Dead is bad, seriously and permanently disabled not much better IMO and watching your home burn could ruin your whole day. Reason enough for caution or avoidance depending on the individuals level of expertise and experience.I was tempted to get into a discussion of circuit impedance and how to calculate available short-circuit currents but figured it would just confuse the situation without providing information that would be meaningful and useful to the poster in this situation. Those who would find the actual short circuit currents involved useful already know how to calculate it. Everyone else just needs to understand that a standard service drop, because of the low impedance circuit path and lack of fusing, is inherently more dangerous than normal branch circuits. That it can kill and that if they don't know exactly what is going on they need to stay away. Installing a line guard is a simple and easy job for the POCO or most electrical contractors. The former will likely do it for free. The later for a nominal fee. Either way is a good option. Well worth the cost for anyone not trained and well equipped.
The current is significant in that a 100 amp arc will get hot and spark, while a 1000 amp arc will virtually explode. At the very least it can make the difference between staying on the ladder or falling off, plus it will likely make a difference in how much molten metal is spraying around.
have the power company kill the power....
how much are you worth to yur family...
rent a generator fer temp power..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
I work for a power company.
We sleeve, blanket, and wrap service drops or any power line that a customer or contractor may come in contact with, at their request. Often we do more than they think they need.
We don't want dead customers. It is bad press, no matter how stupid they are, when they are electrocuted on our side if the meter.
Dave
I recently did a repair to the part of a house that the power lines attached to.
My sparky arranged for the power company to remove the lines completely. I fixed and at the end of the day they came back and put them on again.
It didnt cost a fortune and it was as safe an option as you can get.
If its my arse up a ladder I prefer it this way.
Whatever it was.................I didnt do it.
When I was doing a lot of siding I would schedule the power company ahead of time and then have EVERYTHING ready to go when they showed up. If you explain to the linesman you only need five minutes with the power off they will usually wait and reconnect or repower
"I've been zapped by 220 once, and by 110 a few times (stupid mistakes when I was a youngster), and none of it killed me"
Lots of good advice from people more knowledgable about it than myself. But just my own perspective . . .
Grew up with my father (Ph.D teaching graduate-level electrical engineering in Northern Ohio) doing side work as the professional consultant in court cases involving electrical accidents. House fires, generator shocks, lots of different scenarios. About the one constant was that somebody was always seriously hurt or died. Also, my soccer coach in high school lost his only son a couple of years ago crossing an athletic field with a metal extension ladder. Came in contact with an overhead electrical line, instantly killed him and a buddy. Was taught that you don't usually get a second chance with something like that, and it sounds like you already did. Call the electric company.
Edited 9/6/2005 10:08 am ET by draftguy
Actually, when it comes to electric shocks, you generally survive every one except the last one.
I'd go with having the electric co remove it, use a generator and work fast
we had a run a few years ago where someone was putting out a flag for the 4th of july (i think) with a metal flagpole. they were on the second floor porch - at least one dead, significant injuries to the guy who flew off the porch (electrical and trauma) - wires to the house were too close to the porch/flagpole
Big gains = big risks
little gains = little risks
what 's your life worth compared to pulling the wire
as a totally separate thought - if you're redoing the house, maybe you need to upgrade the supply and/or the location of the drop on the house - justifiable reason to cut the taps
firedude, that's a good thought (upgrading and moving the service) for a variety of reasons. Just for the hell of it, I'll go through those reasons: (1) I've got 100 amp service, and every slot in the box is used; (2) my shop is supplied by two 15 amp circuits (when the table saw, which supposedly operates at 15A peak draw hits a knot or a rip starts binding, it blows the breaker); (3) the circuit box is outdoors, with conduit running up and down the side of the house where it is located, ugly as hell and not something I really want on one of the more visible sides of my 1905 victorian; (4) the overhead supply goes right over the backyard where my kids play, buried would be about 1000 times safer.
The reason I haven't done anything about this yet is quite simple. The only elegant way to do it is to replace all the home runs so that they can get to the location where I'd prefer to put the service drop and the box. That's lots of work and, let's all be honest here, fishing wire just plain sucks. I rate it right up there with mudding drywall and scraping vinyl flooring adhesive among my least favorite things to do.
On the upside, if I don't sell this house next year it'll only be because I'm adding half a level, at which time rewiring will definitely be in order, indeed, absolutely necessary.
not the best way to do it but can't you just do junctions boxes off the old service to the new service? run the new wires as you gut/remodel each room
just a thought
Yeah, firedude, I thought of doing that, in fact, I figured the old breaker box was more than large enough to accommodate all of those conductors, and I could just move it into the crawlspace and use it as a junction box. But then I'm running something like 16 sets of conductors (48 conductors total, at least) from there to the new service location. It's doable, but not pretty. Either way, it's not a project I'm interested in right at the moment. At the moment it's exterior restoration, electrical improvments comes later.
How about changing the service over in phases. First, install the new service entrance in an area where the aluminum siding has been removed. Temporarily run a 100 A feeder from it to the old box, in EMT. Have the POCO move the drop to the new service entrance. Connect the new feeder to the old box, which becomes a sub panel. Disconnect the bond between neutral and ground in the old panel. With the feeder in EMT, it's now safe to remove the aluminum around the old panel. Install a new sub panel (or panels) where you want them to be, and re-route cicruits to them as you go on remodeling.
-- J.S.