Few very basic Electrical questions

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Hi,
I bought a book plus spent a number of hours on the computer to research and I hope someone can help me with just a few very basic questions I still have:
1. I have a 100 amp service. If I turn off the main circuit breaker can I change for instance a 20 amp breaker without worry of shock if I don't touch anything else other than the breaker and the wire that needs to be unscrewed? (I have a few that don't match my GE panel and I heard that they should)
2. I had an electrician once run an extra outlet but in looking a few years later I see that he ran 14/2 cable after attaching this to 12/2 running off a 20 amp breaker. This line either powers a treadmill (runs on a "115 vac dedicated 20 amp {15 amp] circuit") or a iron. The receptacle is 15amp which I believe is fine with either, but should I swap the cable to 12/2 for safety?
3. I also have similar to question two above (14/2, connected to 12/2) going to a GPF in a garage that the same guy did. Do they make a 20 amp GPF and should I switch the cable and the receptacle in this instance too?
4. Can you run a series of five 15 amp receptacles for a workbench in an unfinished basement running on 12/2 on a 20 amp GPF breaker?
I really appreciate all your help!!
Best Regards, Steven        
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No license here so I don't have to cya.
1. You should test it first with a simple tester but the normal answer is that all the breakers and everything below the main breaker is safe to touch with the main turned off. The juice stops inside the main breaker. The lugs above the main breaker are still HOT.
2. I would because de-rating the wire is only allowed (or was allowed) when there is no possibility that it could ever pull more than it was designed for. Example: you wire a single light fixture with 14/2 at the end of a 20 amp circuit.
3. I think they do at a premium price. I would most likely change the wire and leave the GFIC as it is.
4. 20 amp circuits by code require 20 amp devices. There really is no defined limit to the number of devices. The 15 amp ones will most likely work fine and be safe but they are not "to code". Would I use them? Yes because in normal usage you are never going to pull 20 amps.
Your breakers must be rated and tested for the panel they are installed in to meet code.You may want to check the breakers before you go to the trouble to change them. They may be rated for your box. That said there are millions of breakers in boxes all around the world that do not meet that standard. The vast majority of them are perfectly safe and work as they should.
Colbyt
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Incorrect.
The NEC explicitly permits the use of 15A receptacles on a 20A circuit. See Article 210.21(B)(3).
--
Regards,
Doug Miller (alphageek at milmac dot com)
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wrote:

Thanks for the info Doug. All these years I thought I was cheating. I based my assumption on what I saw done in commercial installs. Some of that stuff might have pulled 17 amps on startup so I guess that is why they went with all 20's.
Colbyt
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instance limits the number of devices (a receptacle being one device) on a single circuit to 10. As well, 15A receptacles on a 20 A circuit are allowed by the NEC but for the small difference in price, I'd just install the 20A recepts. Cheers, cc
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the main breaker is open. Never touch a potentially live wire without testing it first!
My breakers don't match my box. But if it bothers you, change them.

difficult, changing the breaker might be better.

circuit, as long as there are more than one outlet. Yes, they make 20a GFCI outlets, but unless you expect to use a 20a plug, it is unnecessary.

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Toller wrote:

You're suggesting that most people replace breakers without turning off the main breaker? Not only is that irresponsible to suggest to the OP, who clearly identified himself as a novice, but on what basis do you even make the claim that most people do it?

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recommended that. I have no hard statistics, but I haven't spoken to anyone who turns off the main breaker so I expect it is the common practice.
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Toller wrote:

Well, now you have. IMO, anyone who fiddles around with circuit breakers without turning off the main breaker is an idiot. I always turn it off. And I seriously doubt that most people don't turn off the main breaker.
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need to do it, there is certainly no harm, other than having to reset every electronic device in the house.
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Toller wrote:

It only gets worse. First, you claimed to a newbie concerned about safety that most people would not turn off the main breaker when replacing a breaker. I believe that is bogus, as most people, myself included would. And now you suggesting that replacing breakers without turning off the power is comparable to unplugging an iron?
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You switch it off, confirm there is no power to the wire, pull it out, disconnect the wire, connect the wire to the new breaker, make sure the new breaker is open, shove the new breaker in. It is a hair more complicated than unplugging an iron, but neither more dangerous nor more difficult. Even if you forget to switch it off, it still should be perfectly safe since you don't touch the wire until the breaker is out of the box; even then it is with a presumably insulated screwdriver.
You should not come within 3" of a live wire, so where do you have a problem? And even if by some bizarre accident, worst came to worst, unless you are working barefoot standing in salt water... Do you wear rubber gloves when you do it, just to be sure? Stand on glass jars? Have one hand behind your back? Maybe pull the meter? Geez.
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Toller wrote:

Have to agree. The normal snap in breakers are very much comparable to a regular 5-15 plug connection.
You are holding an insulated breaker case equivalent to an insulated plug, and you are connecting / disconnecting a spring pressure connection just like a plug.
All is at the same voltages you get with normal plugs, even with a two pole breaker since 6-20 and 6-30 and 6-50 plugs are common household items as well.
If you feel better turning off the main then by all means do so, it's only your time to reset everything that you're wasting, but don't insist that everyone else should do the same.
Pete C.
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Pete C. wrote:

With "normal plugs" you don't have an exposed 240 volt bus on a 100+ amp breaker.

If you want to risk your own life to save resetting a couple of clocks that's your choice. But to advocate that to a complete stranger who admits to being clueless with regard to electrical wiring is irresponsible in the extreme.
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--John
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"J. Clarke" wrote:

<snipped>
With a quality panel (like a Square D QO) you don't have a lot that's exposed either. It's also still only 120V to ground so unless you stick both hands in and touch both legs the 240V part is rather irrelevant.

I never advocated that the OP do anything, I corrected someone's incorrect assertion that most people turn the main breaker off to change a branch circuit breaker. The fact is that most people do not turn the main breaker off to change a branch circuit breaker and in a couple decades of misc. electrical work I've not run across a single person that did.
Pete C.
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Pete C. wrote:

With the cover off the entire bus except those parts covered by breakers is exposed, and it's a lot easier to get your hand across two lugs than it is to get it across one leg and ground, so you're more likely to get 240 than 120.

You are asserting that this is a _fact_. I should like to see the methodology by which you determined this. And don't say "everybody I know" does it unless you are prepared to demonstrate that "everybody you know" is a random and representative sample of the population.
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"J. Clarke" wrote:

First off you should take a closer look at the QO panels, they have a "shielded bus" design that only exposes the actual breaker connection points, the rest of the busses are shielded unlike most other brands.
Second point is that 240V across your fingers may not be nice, but it's still only 120V through your body to ground and that's what counts. Whether you get a lethal current across your heart depends on a lot of factors, but your fingers contacting a single 120V terminal or bridging across for 240V isn't one of them.

I consider the fact that I have not seen a single person do it in 20+ years and hundreds of electrical projects with dozens of people a sufficiently representative sample to conclude that most people do not turn off the main. It would be a stretch to conclude that nobody did, but it's a reasonable assessment that most do not.
Pete C.

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Pete C. wrote:

So? Juice is juice. The "actual breaker connection points" are quite sufficient.

Are you really this ignorant?

Depends on which fingers. One finger, no, one on each hand yes.

I would say that rather than telling us what most people do, you are telling us that you _really_ need to find some smarter friends.
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"J. Clarke" wrote:

Sufficient yes, but it's about 10% of the exposed live bus of most other brands so there is significantly less area to potentially contact.

Apparently you are.

If you're dumb enough to manage to get one hand on one bus and the other hand on the other bus we don't need you in the gene pool.

Nope, at least 75% of those people were professionals and good ones at that who primarily do commercial work, not the hacks that only do residential because they aren't good enough for commercial.
Pete C.

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Pete C. wrote:

If you are located in CT or MA I want a list of these people so I know who to avoid in the future. Otherwise, I'm looking forward to your Darwin Award.
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--John
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