While IAAEE (I Am An Electrical Engineer) I don’t presume to be the ultimate authority on this (Unca Cecil is) I will still comment on a couple topics here;
You can get 20A duplex outlets and some belt’n’suspenders types do use them for increased safety on lines that have 15A wiring (but still have 15A Circuit Breakers). Some go even further and use 20A receptacles and 20A wiring on a line protected with 15A breakers. Some folks feel that this results in a slight energy savings due to less loss in the wire. It might also be required in cases where the outlet is a very long distance from the breaker (which could result in unacceptable voltage drop even at “rated” current).
Most appliances are designed to run on 15A lines because if they required a 20A line that would prevent their use on the vast majority of outlets which are 15A. However, I do believe there are a couple residence-appropriate things like Sump Pumps which you can get in a 20A style, in case you need the extra power.
I’m not sure the “1600W” figure someone listed is correct. 120V at 15A for a purely resistive load is 1800W, and I think I’ve seen some hair-driers with that rating. (I’m skipping over the fact that a 120V line isn’t always delivering exactly 120V)
Regarding “wiring in the last 50 years”; about 30-40 years ago Aluminum wiring was becoming popular as being less expensive than copper. However, it was determined that junctions of aluminum wire to many wiring devices became loose or corroded over time, and thus a fire-hazard. There’s probably still some of that in houses and I’d check if buying a house from that time range. Supposedly things could be done to correct it but who knows if it was done?
No cite, but I think a lot of fires are caused by running high-wattage appliances (like space heaters) over inadequately sized extension cords.
I understand what you’re saying, but there’s another point worth mentioning.
Let’s (again) say Joe Homeowner has a 15-amp breaker, 14-gage wire, and 15-amp outlet. Because of the plug designation, no normal load is going to draw more than 15 amps. And because 14-gage wire is spec’d to safely carry 15 amps, anything you plug into it should not cause the wiring or connections to overheat when operated under normal conditions.
Now Joe installs a 20-amp outlet, and subsequently plugs-in an appliance that draws 20 amps under normal conditions. Contrary to popular opinion, the breaker will not blow, at least not immediately; it may take two or three minutes. (See http://www.dotznize.com/electric/cb.htm for more info.) So does this constitute a dangerous situation? Probably not, but I wouldn’t bet the bank on it. For a given resistance (in a connection), 20 amps will generate 78% more heat power than 15 amps. In other words, if you have a bad connection, 20 amps for 3 minutes may create a hazard, where 15 amps continuous might not. Just something to think about.
Leaving the technical details to the experts (I’m just a humble former lighting engineer) here’s the bottom line on the TV + VCR + Cable Box question: TV’s, unless they’re the ridiculously large kind or ancient, use about 1.5 amps maximum. VCRs, just a little less. Cable boxes, unless wired to a satellite dish (which can then use up to three amps) won’t even use one in North America. Unless you’re living in a castle wired by a 17th century alchemist, throw everything on a power bar with a surge protector or a quality splitter with a 15-amp breaker and you’re sitting so incredibly pretty…
The one thing to watch out for is how many other outlets are wired onto the same circuits… here’s how to find out (if you have breakers… if you have fuses, get someone who knows about electricity): Plug a lamp into the outlet on which you want your TV to run. Turn off one breaker at a time until the lamp goes out. Leaving that one breaker off, try all the nearby outlets (including the ones on the other side of the wall) to see which ones are without power (therefore on the same circuit). Figure that anything that produces heat (heater, toaster, kettle, etc) shouldn’t be on at the same time as your TV, apart from that you’re fine.
This simply isn’t relevant. The normal 15 amp outlet has two places to plug appliances in, and most home circuits have several outlets all on the same circuit. There is plenty of opportunity to draw over 15 amps using several normal loads. If 20 amps for three minutes is a fire hazard, then the breakers need to be redesigned, but your link says that it isn’t a hazard:
ZenBeam: If you reread my post, you’ll notice that I said "it probably won’t be a hazard, but don’t bet the bank on it.” The web site’s assertion that “these overloads for these short times will not cause wiring temperatures to exceed design limits” assumes all connections are clean, tight, and low resistance. Is this a good assumption? Ask your fire chief. My point is that there may very well be a hazard if one or more connections exhibit high resistance…
I agree with this. A 1 horsepower motor takes about 12 amps at 115 V. Motors bigger than this are usually connected to operate on 230 V. The same is true for things like electric clothes dryers.
You can buy outlets that are rectangular boxes about 1 inch deep that plug into a wall outlet having 6 outlet sockets on them . They are held firmly in place by a screw that uses the wall plate screw hole. They are far superior to the “cube tap” type that have three outlets and just plug into the outlet.
There's some wrong and potentially dangerous misinformation here. A 20A duplex outlet is NOT just rated for more current than a 15A duplex outlet -- it also has a configuration that accepts a male 20A plug. (The 20A plug differs from the 15A plug in that it has an extra "Tee" that prevents it from being plugged into a 15A outlet.) So using a 20A outlet on a 15A line is the WRONG thing to do because it indicates that the line can carry 20 Amps and allows someone to plug in an appliance that pulls more current than the circuit is rated for! (In fact, it's likely that there's no difference at all between the 15A and 20A sockets EXCEPT the extra notch in the socket.)
On the other hand, there’s nothing wrong with using 12 gauge Romex to wire a 15 Amp circuit except that the 12 gauge wire is harder to work with.
I use 12-gage wire for all residential 120 VAC wiring, even on circuits w/ 15-amp breakers & outlets. Why?
More power. Let’s say I have a 9-ohm load (e.g. hair dryer, weedwacker) and the distance between the outlet and the breaker box is 100 feet. 12-gage wire will provide 4.1% more power than 14-gage wire.
Flexibility. Let’s say you’re doing some remodeling work and you want to install a 20-amp outlet or breaker on a certain circuit. If there’s 14-gage wire in the wall you’re out of luck.
There are different grades of outlets, residential and commercial, as well as many different manufacturers. So the solidity of the construction may affect how long the outlet lasts, but may not have much to do with its amperage rating. The difference in amount of conductive material used is relatively tiny – small enough so that it might be easier for manufacturers to produce everything at 20A ratings and just label as 15A or 20A.