15 vs 20 amp circuits

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snipped-for-privacy@notmail.com wrote:

Ideally, use 220V on any motor with that option since it allows you to use smaller wire and have less voltage drop and better starts with less light dimming.
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wrote:

I always use #14 for all lighting, and #12 for all outlets, and the associated proper breaker. You dont need 20A for lights, except possibly in industrial applications. Just keep the lights together, in other words, dont mix lights and outlets, with the possible exception of closets, where one might add an outlet for occasional use to the lighting circuit, or maybe the same in an unfinished attic.
One reason that I learned from an electrician many years ago, was that light bulbs occasionally short internally when they burn out. A 15A breaker will trip faster, so those bulb incidents are less dramatic and less chance of shattering the glass.
I just rewired a barn for a friend. He did not want to change the old fuse box. He's retired from farming and dont have livestock anymore, but his light fixtures were all nasty and corroded, and half of them no longer worked. He also had an outlet that had gotten a bolt of lightning and was all charred and being held together with electrical tape. The lighting wires themselves were all still good because they were #12 UF cable. The only problem was this was the UF without ground. But at 30 to 40 feet off the floor, we decided that as long as the lights were porcelain in plastic boxes, there was no real need to a ground wire, as this wire was "grandfathered in". However, we replaced all the wires for the outlets. Even though the lighting wires were #12, I installed a 15A fuse. There are only five lights w/ 100W bulbs. No sense using a 20A, and as I said earlier, if a bulb shorts, it is less likely to shatter the glass. Particularly in a barn where there is hay and stuff like that. (he still bales and sells hay).
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Do you understand what an order of magnitude is? An order of magnitude is a factor of 10. Two orders of magnitude is 100X. So, you're telling us it's at least 100 times more difficult to run 12 gauge than 14? A job that would take an hour, now takes 100 hours?
I use 12 only for

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t4:
A double cheeseburger, a basket of chili fries, coleslaw, and three cups of strong black coffee. Not only does this order have magnitude, it has direction. I will spare you the gruesome details. Let's just say that 1.6 gallons just won't always do.
Aaaanyway, there's nothing wrong with Edison circuits if they're not stupid. Stupid, for instance, would be an Edison circuit that splits 10 feet from the panel. Well, we're not going to save much power or material there, but we do keep the potential for 240v across the light bulbs if somebody didn't screw down that crummy drugstore wirenut real good,so there is a bright side, a flash of genius, even.
The advantages of a multiwire or Edison circuit, for those who might want to know, include material cost and energy savings from less voltage drop. I see no reason to avoid them, where conditions are favorable.
There is really nothing stopping any homeowner who really wants to do his electrical work right from going out and learning about all the different legitimate arrangements one might find in an electrical box. I suggest PRACTICAL ELECTRICAL WIRING as a start. One should not wire with nothing more than "white wire, black wire" to go by.
Cordially yours: G P
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snipped-for-privacy@gannon.edu wrote:

Yep, plenty of adequate reference material available at the Depot / Lowe's book section as well as *gasp* your local library. Pretty much any of those books would even explain how to properly wire a "4-way" switch arrangement (yes, 4).
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Abolutely I understand the concept of order of magnitude. When I was doing my wiring I found it an orders of magnitude easier to use 14 rather than 12. I didn't say faster, I said easier.
mike

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I read the dozen or so replies and two things come to light. If you are using #12 the push in terminals are not an option anyway. They are only listed for #14. #12 won't even fit unless you really force/drill it into the hole.
The second issue is 15a vs 20a O/C protection. There are people who say you are giving up 33% of your safety when you put an 18ga lamp cord on a 20a circuit. It is still legal but bear in mind you are protecting 7a wire with a 20a breaker.
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snipped-for-privacy@aol.com wrote:

How is this substantially different from putting that 7A wire on a 15A circuit? The circuit breaker is there to protect the wiring in the house (i.e. the 12 or 14 ga wire), not to protect the appliance wire. Appliances typically have their own fuses, basic lamps being one exception. If that 18ga lamp cord gets damaged and shorts, the short circuit current is not limited to the 7A rating of the 18ga cord, and will be well over 20A, tripping the circuit breaker regardless of whether it is a 15A or 20A breaker. If it's in a bedroom, the new AFCI breakers will trip if the cord is damaged and arcing, but not a full short.
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wrote:

I agree it is not a serious concern but it is the one argument I have heard about using 20a circuits for general lighting circuits.
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The key concern is overloads. Both 15 and 20 amp breakers will trip on direct shorts (if they are working properly).
There is a tradeoff.
20A circuits have a convenience factor with the ability to delivery a considerable greater amount of power to a given situation. A typical example today would be a home office with multiple monitors, printers, computers and accessories in addition to whatever other routine loads (vacuum cleaners, electric heaters, etc.) are placed on the circuit.
That extra 5A capability might just be the difference between adaquate wiring or a long-term headache of a constantly tripping circuit breaker.
On the other hand, the subloads on a 20A circuit might (possible) pose a safety issue. The 18 gauge lamp cord example has already been mentioned.
The danger being that if the 18 g. wire is overloaded just enough for the 18 g. wire to melt, but not enough to trip a 20A breaker. (In such a case, a 15A circuit breaker might be more likely to trip than a 20A breaker, but not necessarily). This is the reason that most power strips contain their own internal circuit breakers.
15A circuits were standardized during a time when there where few constant electrical loads and the loads were generally light. (a few lamps, a fan, etc.).
These days, many people have home entertainment systems, hefty audio amplifiers, air conditioners, computers, big-screen plasma tv's, monitors, laser printers, and a whole lot of loads that could not be imagined 60, 70 or 80 years ago.
In my opinion, this makes the argument favor the 20A circuits over 15A circuits, just for the added capacity and convenience.
Beachcomber
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On Mon, 24 Sep 2007 16:10:22 GMT, snipped-for-privacy@notreal.none (Beachcomber) wrote:

The CORRECT solution to this situation is a split 15 amp circuit. 15 amps to the top outlet, 15 to the bottom. Done by using 14/3 cable and double breakers. The legal way is a "tied breaker" which means if you blow one, it trips the other as well. This is to prevent half of the box being live. Untied breakers are often used for this reason.

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clare, at, snyder.on.ca wrote:

Doing that will also put the two outlets on opposite poles / phases, giving 240V between the upper and lower hot connections. I'm not sure how that works with the ratings of the break off tabs on a duplex receptacle. At any rate a hinky solution at best.
The truly correct solution is to just install more circuits in locations that need them. Basically instead of the all too common situation of every receptacle in a room being on a single 15A or 20A they should be individual circuits or at least two circuits alternated so any given location is within reach of both circuits.
The alleged safety concerns of 18ga lamp cord on a 20A vs. 15A circuit are pretty much all bunk. The wire is rated at less than half of what even the 15A circuit is rated at, the 20A circuit introduces no additional risk. In both cases the circuit breaker properly protects what it is designed to protect - the wires in the walls. In neither case is the circuit breaker supposed to be the protection for the lamp cord and the liklihood of a fault developing in the lamp cord that would trip a 15A breaker, but not trip a 20A breaker is virtually non existent.
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Pete C. wrote:

No, this is not a hinky solution. It's called a splitwire or multiwire circuit, and has been the standard for kitchen counter receptacles in Canada for decades.

Having every receptacle on its own circuit is ridiculous overkill. Even having two circuits per room is overkill for many rooms. That said, there are some rooms (kitchens, home theaters, home workshops) that would benefit from more circuits, and just about any room would benefit from more receptacles.
Chris
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It's also quite common in office building environment. A variant of this is when you have 3-phase 208VAC available. You can run all three phases and a neutral in the conduit and use a different phase and neutral in each box. There are some issues with the size of the neutral, but I won't go into that here.
By using just one phase and neutral in each box, you avoid having higher than 120VAC available in one outlet. This can also be done with residential circuits, use alternating 'hots' in each successive box. So box 1, 3, 5, etc... is off of the first 'hot' and 2, 4, 6, etc... is off the second 'hot'.

There are many times I wish there were two receptacle boxes side by side in a 'quad-outlet' arrangement. Just because of the number of things to plug in, not the overall VA requirement. In a modern home office you might need a total of about 400 VA (about 1/3 of a 15A circuit capacity), but it's split into six or more 'plugs' (couple of watts for speakers, couple of watts for radio, couple of watts for cordless phone, 7-15 watts for CFL, rest for computer and printer).
Even my bedroom, with a reading lamp, wireless telephone, alarm clock for me, and an alarm clock for the Mrs., I end up needing an 'adapter' while the four other outlets in the bedroom are empty. Total load: about 11 watts (when the 7 watt CFL reading lamp is on).
daestrom
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daestrom wrote:

He's talking about splitting poles / phases on the upper and lower halves of a duplex receptacle, not using a different phase in successive box locations.

I'm good with cycling through the phases from box to box, but not splitting upper and lower of a duplex.

I wired my shop with all "quads", each one is a 20A GFCI receptacle paired with a 20A regular receptacle, and each "quad" is a separate circuit. The "quads" are spaced every 6'. The shop has a 125A 32 space Square D QO sub panel.

That's another issue, a zillion tiny loads in one spot. I have a power strip under my night stand for the table lamp, alarm clock, cordless phone charger, cell phone charger, bluetooth headset charger and weather radio (tornado alley).
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Chris Friesen wrote:

I'm sure the world will get right on adopting those superior Canadian electrical standards...
My kitchen has I believe four separate 20A circuits in it, and it was that way when I got here. I did have to replace the Federal Pacific Stab-Loc main panel incendiary device with a proper Square D QO panel however.

My shop is wired with a "quad" every 6', with a "quad" being a 4" square box containing a 20A GFCI duplex receptacle paired with a 20A regular duplex receptacle. Every "quad" is an separate circuit. All wiring is in surface mounted conduit for ease of additions / changes. 240V receptacles are located where needed. The walls are type X fire code sheetrock. I'm pretty happy with it for a home shop.
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It's called an Edison circuit. It's used all over. There's nothing "hinky" about it.
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Noozer wrote:

No, it is not called an Edison circuit, though it connects to one. Feeding separate 120V devices from a three wire feed is called an "Edison circuit", feeding upper and lower halves of a duplex receptacle from separate legs / phases is not in the definition of an "Edison circuit".
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CSA is superior to UL... There's quite a bit of cross-pollination between the two standards.
The US _used_ to have multi-wire kitchen counter outlets.
Having 30A worth of 120V at every counter receptacle is better than 20A.
However, now that we're going to requiring GFCIs for kitchen counter outlets, split-wire GFCI outlets are non-existant, and double GFCI breakers very expensive, we're switching to the US 20A GFCI standard. But split-wire kitchen counter outlets are sitll perfectly legal if you don't mind paying for double GFCI breakers.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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