I have done alot of DIY for the past 20 years on my home. However the one thing I still do not feel comfortable with is doing work in the service panel. I recently purchased a dual fuel gas range and installed it myself. I ran a separate 50 amp 240 volt circuit. i need to run the #6 wire into the serivce panel to a separate breaker.
My question is does anyone know of a product out there or any other means of protecting yourself so that one does not accidentally hit the service feeds whle working in the panel and then ensuring a bad day?
Thanks.
Replies
yes, pull the meter
yes, pull the meter
AMEN...a very hard to find product at times but worth the look..... "Comon sense"
A lot of difference between sneaking a single run of 12 or 14 and tryind to get someting heavier inplace in a live panel. I'm lucky to have exterior disconnects for each panel so it's a no brainer.
Yes, Pete!!
"Common sense ain't all that common, is it?" From Mark Twain, I believe.
EDIT: Just checked and saw that Will Rogers spoke those words.
Edited 12/6/2005 8:12 am ET by experienced
240 volt, 50 amp??? .. that seems like allot, are you sure, must be one hell of a trophy stove ..
Doesn't sound that big. Especially if it is a free standing cooktop and oven.
Just installed a wall oven / microwave unit which called for a 40A 240v.The matching cooktop called for a 30A 240.
Jim
Never underestimate the value of a sharp pencil or good light.
Just installed a wall oven / microwave unit which called for a 40A 240v.The matching cooktop called for a 30A 240."
JT,
And my double wall oven called for 240V 40amps also, and my welder 240V 50amps.......and the line coming out of 'um both was 12 gauge. What does that tell you?
WSJ
And it was stranded wire, too, wasn't it? Yeah, go figure!
And it was stranded wire, too, wasn't it?"
How'd you guess?lol
WSJ
"....and the line coming out of both of them was 12 ga. What does that tell you?"
Don't know for sure, maybe that you can cram more amps through a skinnier wire for a very short run, maybe that the insulation used is an exotic high temp type, maybe that the appliances don't really need their specified supply amperage,......
Not an electrical engineer, I just like to stay out of trouble with the inspectors by following the manufacturer's recommendations. My policy has always come in handy in the past if there were any power related warranty issues.
Maybe it's sort of like Caterpillar Marine Engine Division. 3208 Turbo set up with a heat exchanger; has a raw water pump with an inlet of 1"D., yet their installation specs call for a 2"D. seacock, strainer and inlet piping/hose all the way to the pump inlet - you then neck the supply down with a bell reducer at the inlet side of the pump. 2" is ~4X larger than 1" in cross section; This spec allows slop for piping bends, less than perfect laminar flow in the pipes and hoses and perhaps some partial blockage of the feed line without starving the engine of cooling water.
Perhaps the 40A service allows for a long wire run and a few less than perfect connections?
What does the 12 ga tell you?
Jim
Never underestimate the value of a sharp pencil or good light.
What does the 12 ga tell you? "
Max continuous draw....20amps.
WSJ
Thye #12 house wiring may be rated for 20 amps but the intent of most electrical codes is to load it to 80% of rated.
"And my double wall oven called for 240V 40amps also, and my welder 240V 50amps.......and the line coming out of 'um both was 12 gauge. What does that tell you?"I'm not sure what's going on with your oven, but section 630 in the NEC does allow for smaller wire than you would expect for the supply conductors for a welder, based on its duty cycle. The shorter the duty cycle, the smaller the wire can be. The welder manufacturer probably did something similar when they sized the power cord.
NEC permits "pigtails", the short manufactured in/on feeds to applicances to be of higher gauge (i.e., smaller) conductor than a feeder or branch circuit conductor.
Not to hijack this thread but rather a similar question...
I'd like to cut off all incoming electric power so I can recess the panel in a redundant brick wall. Any ideas for this? Can I shut off power at the meter, or does the power company do this? Thanks.
I know that utility companies don't like you doing that
Some have a special lock that when broken the company knows someone else did it
Have the utility company pull the meter
You can't touch the meter, that's the power company's. You're going to have to get them to d/c your service, do the work, get it inspected for compliance with the NEC, then the company will re-energize your service.
It was a Wolf 48" with a convection oven that draws the power
It should be obvious, if you don't feel comfortable working in the panel get a qualified electrician to do it. Even qualified electricians drop tools inside panels or bump something they dont mean to and burn themselves badly if they leave a panel live and make a mistake. There is almost never a justification for leaving a panel live when working inside of it. Pulling a meter is usually illegal and always extremely dangerous. They have been known to fall apart when pulled.The posts about proper safety equipment, gloves, goggles, cotton clothes are all musts when working in any panel. The main should ALWAYS be turned off, once the main is off the bus bars that the branch breakers plug into are dead, only the terminals where the service conductors enter the main breaker are still live at that point. Take a dry corrugated cardboard box and cut a piece of cardboard large enough to completely cover the main breaker terminals and 6 or more inches in each direction away from them and duct tape that to the plastic face of the main breaker and well above the terminals to keep your hands and tools from being able to accidentally make contact with those terminals. At that point you can connect your wires safely.
>>>a dry corrugated cardboard box and cut a piece of cardboard large enough to completely cover the main breaker terminals <!----><!----><!---->
<!----><!---->
Around here (<!----><!----><!---->Canada<!----><!---->) the main connections are covered with a grounded metal shield inside the panel; the idea being that you can shut off the mains, which kills the two buses, and now you can work inside the panel with relative impunity. Is this not the case where you are?<!----><!---->
<!----><!---->
Scott.
Edited 12/6/2005 10:31 pm ET by Scott
To Scott: I have heard about the protective cover required in Canada. That's an excellent idea and should be universally required but that's not the case here.As to the disconnect between the meter and the panel, although that is a very good idea, it is very rarely done in practice in most areas because of the additional cost. Typically we see an exterior disconnect only when required because the service panel is located somewhere remote in the house and not immediately inside from where the cable enters the house. Most jurisdictions limit the amount of interior unfused cable to around 6' or less, although that varies a bit. The NEC allows the distance to be determined by the AHJ.As to the electricians who work live without any protective gear, they have been lucky and careful to date, but eventually your luck can run out. Someone who worked for the same firm I did dropped an allen wrench down the inside of a grocery store main panel and spent weeks in the hospital. The next grocery store I worked in was done at night when the store was closed with the mains off.
Thanks for the note. I have done quite a bit of work in the panel for many years but I just had a friend working in his house slip and hit the damn service feed. Luckily he just got alittle 110 in the finger that was it.
I have read about electricians slipping or mistakenly hitting the feed with a screwdriver. I agree with the protection, I always wear gloves, glassed and rubber soled boots and work only with one hand in the box.
Amazingly I watched the electrician hook up this #6 cable yesterday and he didn't even shut off the main which I thought was crazy.
Have you ever seen a disconnect between the meter and the panel? Some peope have told me this is a good idea, this way you can shut off the feeds to the box.
The cardboard is a good idea.
Just learned something about the little shocks we get that I didn't know before!! A friend went to a home inspectors' conference wheer they did a session on electrical safety.
We use GFCI's to stop shocks with currents down to about 10 milliamps- not much current. Why so little? Our body circuits measure in the microamps....1000 times less. The little current (LC) we may draw from the little shock does not kill us in the same way that the 6600 or so volt driven current that a downed powerline might- immediately and finally.
What happens occasionally is that LC interferes with electrical circuits/current controlling heart beat rhythm. Whne this happens, you have 4-6 minutes to get defibrillated and get back to regular heart beat!!
I thought that this event would occur immediately after the little shock. The new info I got is that this may occur for a few hours after the shock!!! It was recommended to go to a hospital and wait for a few hours, just in case.
A lot left to learn at 55 years old!! Guess it's like one of my college football coaches used to say "When you're done learning, you're done!!"
A friend of mine who is an electrical engineer said 50 miliamps could kill you.
So msall voltage and low resistance could get you.
Yep, that's not far off. Usually it's 70 to 100 milliamps but you won't be able to let ago above 20 milliamps as the current will cause all of your muscles to tighten. Unless someone is there to "bump you off" then it's quite possible you'll be aware but unable to do anything until it reaches 70+ milliamps, which will happen ridiculously fast.I always like to indicate the amount of current in Amps. Somehow typing that 0.07A on a 15A circuit will kill you has a better effect than typing 70 milliamps. Maybe it better shows just how little it takes to kill you.
You are right.
"Common sense" is one of the most un-common traits.
Despite the humorous answers, it's just like when you arm a Claymore mine -- you slowly push in the cap -- oh, you didn't do that, did you? Okay, it's like when you saw the Tesla coil in high school and the direct current jumped a six inch gap, well AC isn't that way. It doesn't leap out at you from a foot away. So don't touch it, is all. It isn't going to arc at you. Just be careful and concentrate on what you're doing. Don't be watching a football game as you're doing this, as that touchdown pass could hurt.
Working in the inside service panel is like crossing the street, just don't get hit by a bus. Work slow, stand on some ceramic tiles and use just one hand in the box. keep the other in a pocket or something. If there are breakers that you feel you need to get close to, just shut them off not the main. Having said all that, if you do not feel safe working then you should not open it up.
Stand on ceramic tiles? For what? I could understand hopping onto a nice big piece of dry plywood, but would think the tiles would ground you as much as anything else. Baked clay is just another form of dirt. Or is the glaze what saves you?
Don K.
EJG Homes Renovations - New Construction - Rentals
I used to use plywood, then one day a sparky told me to use tiles. Now that I am thinking about it you have a good point.
Short of pulling the meter [which may be illegal] or dealing with the power company, there are some things you can do to increase safety. Known as PPE [Personal Protective Equipment], this would include insulated gloves, goggles, face shield, long sleeve cotton shirt and so on.
The thing to watch out for is the bus bars. These are live from the utility's transformer and are not protected by any fuses or circuit breakers worth mentioning. Touching them is just a 120 or 240 volt shock which you may be able to survice. But getting some metal to bridge between then or between one and ground and you could have 10,000 amps running through your screwdriver. And it isn't designed for that. It heats up to 15,000º and vaporizes and explodes.
So use insulated tools. Know what the busbars are. [And don't touch 'em.] It is surprising that manufacturers don't cover all bare bus bars with some sort of plastic insulation. A common apprentice technique is to install a cardboard shield over the dangerous, hot parts.
Strip only one conductor at a time. A clean cut wire would have to be pretty lucky to land smack dab on a live bus bar but a striped end has copper exposed on all sides. Have the circuit breaker[s] off of course. Sometimes these wires will flip around erratically.
~Peter
Contribute to the Seatle-Tacoma earthquake disaster relief fund.
I'd like to add : remove watches, jewelry, rings
... do not use foot long non-insulated tools
TURN the MAIN..OFF
Edited 12/6/2005 7:35 am by maddog3
thanks
Can I put a volt meter probe on the busbar?
In a panel, the bus bars are usually vertically oriented. You can try to put your voltage probe on it but it will probably fall off.
But if you are just going to test for voltage, this shouldn't be a problem. This is one instance where it is necessary to work live.
Somewhere below someone brought up a point about a disconnect being required. So there should be a disconnect ahead of the main panel or at least before the bus bars.
~Peter
Help the survivors of the Seatle-Tacoma earthquake.
"The thing to watch out for is the bus bars. These are live from the utility's transformer and are not protected by any fuses or circuit breakers worth mentioning. Touching them is just a 120 or 240 volt shock which you may be able to survice. But getting some metal to bridge between then or between one and ground and you could have 10,000 amps running through your screwdriver. And it isn't designed for that. It heats up to 15,000º and vaporizes and explodes"
Aren't the busses protected by the main breaker? If you shut that off, wouldn't they be dead? Or are you talking about the incoming feed above the main breaker?
That's exactly what I was on about. A service panel should (must?!) have either a fused switch or circuit breaker between it and the meter. If it's not there, it should be! And any sub-panel must have a breaker in the main panel to feed it. So there's never a need to work on a live panel.
The main breaker in the panel serves as the service disconnect. Some jurisdictions require a second service disconnect, usually outside of the building.
When the main breaker in the panel is thrown to the "off" position, it de-energizes the buss bars and all of the branch breakers.
However, the connections (lugs) to the main breaker remain energized and, in most cases, exposed.
Jim
Never underestimate the value of a sharp pencil or good light.
> When the main breaker in the panel is thrown to the "off" position, it de-energizes the buss bars and all of the branch breakers.
> However, the connections (lugs) to the main breaker remain energized and, in most cases, exposed.
That's what I see most of the time. If I'm going to be doing much work in such a panel, I put a couple layers of good gaffer's tape over the hot lugs. And check carefully with the neon light to make sure I've found all the hot parts. Pretty much equivalent to the Canadian requirement, but the cover isn't metal, and therefore not conductive.
-- J.S.
Good idea to get things covered up while working.
I wonder how many readers know that gaffer's tape = duct tape? That is a term I rarely hear outside of the film / photography business.
Jim
Never inderestimate the value of a sharp pencil or good light.
My daughter bought a house that needed a new service panel. I went to Lowes and talked to the city electrical inspector that works there part time and figured out in my mind how to swap out the panel. He said, in our county, you simply cut the wire seal on the outside meter, and pull it out (top side first). When you are done, replace it and slip the wire back on. When the meter is read, the meter man will look it over and put on a new wire seal. Oh....It took me 3 hours start to finish....not bad for my first time.You get out of life what you put into it......minus taxes.
Marv
Thats pretty good for the first time. I suppose it depends on how many circuits you have in there. The key is to be neat with the wires.
> gaffer's tape = duct tape?
Well, actually not. Real gaffer's tape has a much stronger fabric backing and a much stronger adhesive.
-- J.S.
Busses are protected/fed by the main breaker; shutting off the main breaker should kill them. Always good to check with a meter - theoretically the main could malfunction and not shut off one or both of the busses.
The incoming feed connections are not protected and the only way to kill them is by pulling the meter; unless there is a main disconnect outside, it would be between the meter and the SEP I believe. If main disconnect is installed then you can throw it to the off position - still check with a meter at the panel. Main disconnects are required by some jurisdictions, not mine however.
Jim
Never underestimate the value of a sharp pencil or good light.
Two boxes. I've got one in the basement that's just a kill switch to the whole house, then one in following that upstairs in the mudroom which has a second kill switch and all the breakers. To kill the one with the meat, I can just go to the basement and throw the main kill.
Homeowners are gonna mess around in these sooner or later, I'm suprised this configuration isn't more standard. I've not seen it before but it makes some sense. Of course, you'd have to get and Elec. to install it, but then you can do what you want whenever.
A service panel will have a main feed breaker at the top of the panel you can shut off, which disconnects both bus-bars from the feed power. A sub panel (one without a main feed breaker at the top) will have a breaker or fused switch that feeds it from the main panel. Unless you're working on the main feed line in from the meter, there's no need to pull the meter itself.
Do not work on a live panel if you're worried about it. If you're worried, you're likely to hurt yourself. If you understand how a panel works and take the proper precautions, it's not all that dangerous to work on one live. But if you're afraid, just say no.
If you do choose to work inside the panel while it's live, the best advice is to work with one hand in your pocket. The most dangerous shocks are from hand to hand through the chest.
Thanks to everyone on the responses
i think I am going to go with having a disconnect installed between the meter and the panel
In any event i got a licensed electrician to do the hook up. #6 wire is not thta easy to work with.
Re: ..."does anyone know of a product out there or any other means of protecting yourself so that one does not accidentally hit the service feeds whle working in the panel"...
Not too me too trite but...
Yes, it's called an electrician.
If you, or anyone else, doesn't know how to work in a panel without risking life and limb you/they need to stay out.
And toughing out with gritted teeth and cold sweat isn't the answer either. I watched a helper who wouldn't admit he was terrified work a panel. A wire vibrated when he moved it and he took this as the begging of a shock. He ended up dropping his screwdriver across the buss bars. Very exciting. No big problem as we were replacing the panel anyway. He quit the next day.
Point being if you don't know admit it to yourself, a man's got to know his limitations, and find someone who does.