Another wiring question

[jking]

I'm pretty sure I have a book on wiring written by a licensed electrician where he talks about it being perfectly fine to run romex in conduit. The book mentions that it will be difficult to pull, but, the wires will be protected better. The book is supposed to be based on the latest NEC.[?]

[don_hart]

There are only limited applications where a sheathed cable can be run through conduit and a normal circuit run is not one of those applications

[WoodRook]

mschrank - I used 20A outlets for my 20A circuits. They were a bit more expensive than 15A outlets but I think they are more "solid" (i.e., better made, more heavy duty).

jking - my belief that romex should not be pulled through conduit is only based on discussion with various people. It would be interesting if you could verify your recollection.

Here's some interesting reading (if you're so inclined); hope the links work:

http://www.selfhelpforums.com/showth...=romex+conduit

http://www.selfhelpforums.com/showth...uit+fill+table

Basically, these say that romex is OK in conduit if it's a protective sleeve (open on one end). If it's a true conduit system (closed), then you have to consider the "conduit fill table" & derate the wiring (not to mention how hard the romex is to pull).

[Hoover]

Canada has different wiring codes than the US. So don't take this info for gospel. Better check your national codes, I recollect different grounding requirements for one.

[mschrank]

Thanks for the links, WoodRook.

Hoover, I only mention the Canadian codes because they seem to imply some hazard associated with using 20 amp circuits.

I've pretty much decided to install 20 amp outlets thoughout the garage, and I won't run the Romex inside conduit. If anybody can provide some insight into why I should or should not use the 20 amp outlets, I'd love to hear it.

Thanks,
Mike

[BobSch]

quote:Originally posted by mschrank



I've pretty much decided to install 20 amp outlets thoughout the garage, and I won't run the Romex inside conduit. If anybody can provide some insight into why I should or should not use the 20 amp outlets, I'd love to hear it.

Thanks,
Mike

So would I as that's my plan, too. I'd even considered running 12/3 to each outlet with two hot wires, one on each side of the incoming 220, then split the outlets so each one could handle 20 amps and any box could give me 220 by just changing the outlet.

[Rand]

>>>So, is there any harm in putting in 20 amp outlets (provided the wiring and breakers are rated for it)? If I don't have any tools that require 20 amp, is there any benefit to installing them?

Typically when you wire an outlet you connect the 2 black wires to the brass side of the outlet and the 2 white wires to the silver side. This runs the circuit through the outlet and on to the next box. If you have 2 or more devices plugged into the same circuit you could be running more than 15 amps through any outlets that are closer to the panel. I am not an electrician but I don't think that's a good idea. To get around this you could wire nut the sides of the circuit together along with a short tail to feed the outlet. If I were you I'd use components that all had the same rating.

Rand

[maxparot]

quote:Originally posted by Rand

>>>So, is there any harm in putting in 20 amp outlets (provided the wiring and breakers are rated for it)? If I don't have any tools that require 20 amp, is there any benefit to installing them?

Typically when you wire an outlet you connect the 2 black wires to the brass side of the outlet and the 2 white wires to the silver side. This runs the circuit through the outlet and on to the next box. If you have 2 or more devices plugged into the same circuit you could be running more than 15 amps through any outlets that are closer to the panel. I am not an electrician but I don't think that's a good idea. To get around this you could wire nut the sides of the circuit together along with a short tail to feed the outlet. If I were you I'd use components that all had the same rating.

If the breaker and cables are of the proper rating there is no harm.
You will get the protection of the breaker at each of the outlets on that circuit.
You do not need to pigtail the wires to the outlet. The screws are there to make the circuit. Since the outlets are rated the same as the breaker it is safe to use devices rated for the breakers limit at each outlet. When the total draw exceeds the breakers limit it will open turning off the circuit and protecting the cable and all outlets.

[Tom Miller]

I think Rand was suggesting that the disadvantage to installing 15A outlets on a 20A circuit is that, if the 15A receptacle is being used to connect the downstream portion of the circuit (by way of the lugs), it won't have the proper 15A breaker protection. Pigtailing the 15A receptacle to the 12ga (20A-rated) wire would solve that problem.

Did I get that right? I didn't catch that point at first, and it seemed pretty astute. But I'm no electrician (Ph.D. in electrical engineering, but trust me, I know it ain't the same!).

Regards,
Tom

[Stick]

quote:Originally posted by mschrank

So, is there any harm in putting in 20 amp outlets (provided the wiring and breakers are rated for it)? If I don't have any tools that require 20 amp, is there any benefit to installing them?

I remember reading some code guidelines somewhere...I think it was for somewhere in Canada...that mandated no greater than 15 amp circuits in certain rooms. That leads me to believe there may be some potential hazard associated with 20 amp circuits.

Mike

Only place I know of in residences under Canadian code that aren't supposed to have bigger than 15A receptacles is in washrooms. Heater circuits and such are allowed but they have to be hard wired.

It's actually funny, our code IS much more strict in a lot of areas, and decades ahead in some, yet 20A circuits at 120V are relatively rare here, even in new construction. I'm surprised though, that someone went to the slight added expense of the 20A breakers and 12ga wiring but never put in the 20A receptacles.

My shops are done like BobSch suggests, and like kitchen receptacles are done, so that each outlet is fed from a different circuit. Also they're fed so that no two adjacent outlets are from the same circuit.

[LCHIEN]

Not sure its against code or whatever,
but I think the connecting link in the 15A sockets to allow them to be wired through is way more than enough to handle 20 Amps - and its only
1/4" long, not enough resistance to be electrically significant. Looking at the construction of a Leviton 15A outlet, I see that the link width and thickness is equal to the metal link connecting the
push-in (back) connections and the side terminals to the outlet. In either case the length of those links is around an inch or more. If you can carry 15A in an inch long segment then you can surely carry 33% more in a 1/4" long segment.

One reason you may wish to have a 20A circuit with 15A outlets is you have several loads adding up to more than 15A but no individual load more than 15.

Equipment requireing a 20A circuit and equipped with a 20A plug (the one with one blade turned sideways/horizontal)
are pretty rare and mostly confined to industrial-type equipment,
I've not seen any in retail consumer stores or on consumer equipment.

[Rand]

Tom,

That's exactly what I was trying to say.

Loring,

I don't think the issue is length or resistance. I think the difference is the mass of the conductors built into the outlet. Heavier metal carries more current without heating up. That's why thicker wire is code for more amperage.

Again, I'm no expert on the stuff but:

If you are correct (and you might be) that the strip of metal in a 15A outlet is enough to carry the extra amperage over a short distance then why would they make 20A outlets at all? The distance between the connecting terminals and the part where the device plugs in is pretty short too.

Rand