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15 amp for homes? Why not 20?

Question:

I am rewiring my home with all circuits 20A and "commercial grade" 20A outlets. Space heaters – No problem now!

Response:

Breakers are sized to protect the wiring, not the appliances.  If you have 14 gauge wire you need a 15 amp breaker. I disagree, breaker should be sized according to the expected usage of the line, not the size of the wire feeding the circuit!

Not really. The expected usage of the line is determined by it’s placement. A circuit in a bedroom is not expected to have a toaster oven and a coffeemaker plugged into it. The load in a kitchen or dining area is expected to have a higher load, and is sized accordingly. That’s not to say *someone* wouldn’t want to utilize a 1500 watt heater in a bedroom… effectively consuming 5/6ths of the power available… It just doesn’t occur frequently enough for the code to consider the practice commonplace, and then provide for it.   (Wire should be at least heavy enough gage to handle full breaker load)  The coffee maker example  could start a fire if breaker is too high a value to trip in case of a short in appliance. The breaker is to protect ME and the house. Walt Conner I got a coffee maker that pulls about 12 amps. If it decides to pull over 15 amps, I want that fuse/breaker to blow/trip. I don’t want it to wait until it gets to 20 amps before it trips.

I don’t think that many devices which are "starting to fail" begin to slowly pull more amperage… Typcally an appliance fails due to a corroded or loose connection or simply an open circuit (element burns out) or some mechanical failure (safety switch cutout, thermal overload) Of course, almost all electrical faults are typically described as "shorts", though few actually are. Path: lobby!ngtf-m01.news.aol.com!portc01.blue.aol.com!feed1.newsreader.com!net

news.com!xfer02.netnews.com!newsfeed2.earthlink.net!newsfeed.earthlink.net !newsmaster1.prod.itd.earthlink.net!newsread1.prod.itd.earthlink.net.POSTE D!not-for-mail – Hide quoted text — Show quoted text – Newsgroups: alt.home.repair References: X-Newsreader: Microsoft Internet News 4.70.1162 Lines: 19 NNTP-Posting-Host: 208.235.45.10 X-Trace: newsread1.prod.itd.earthlink.net 1011623147 208.235.45.10 (Mon, 21 Jan 2002 06:25:47 PST) Organization: EarthLink Inc. — http://www.EarthLink.net (newsmaster1.prod.itd.earthlink.net)

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Response:

Breakers are sized to protect the wiring, not the appliances.  If you have 14 gauge wire you need a 15 amp breaker.

I disagree, breaker should be sized according to the expected usage of the line, not the size of the wire feeding the circuit!  (Wire should be at least heavy enough gage to handle full breaker load)  The coffee maker example  could start a fire if breaker is too high a value to trip in case of a short in appliance. The breaker is to protect ME and the house. Walt Conner – Hide quoted text — Show quoted text – I got a coffee maker that pulls about 12 amps. If it decides to pull over 15 amps, I want that fuse/breaker to blow/trip. I don’t want it to wait until it gets to 20 amps before it trips.

Response:

- Hide quoted text — Show quoted text –  I’m told Canada has a similar bugaboo about 20A – instead of the US T- blade receptacale (5-20R) the Canadian version only has the horizontal slot, so you can’t even plug a 15A device into a 20A circuit. With an exception for a specific application in commercial installations, in Canada no outlet can accept more than one type of plug. An outlet rated for a certain voltage/current can only accept that same type of plug. 20A circuits are quite rare in Canada in residential installations. In kitchens, our counter outlets must be split, so we effectively have TWO 15 A circuits feeding a single outlet, one for the top and another for the bottom. That gives you 3000 Watts per outlet, allowing you to plug your toaster AND your electric kettle (something that is rather hard to find in stores in the USA, I find) into the same outlet at the same time.

You people (and Europeans) tend to cook differently than we we do. You’re more into those one-pot meals than our 4-course dinners… One course cooked on a George foreman grill, one cooked in the showtime grill, one deep fried in the fry Daddy, and the last broiled in the toaster oven! I forgot the exact numbers… but Americans represent something like 15% of the world’s population, but consume 75% of the worlds energy resourses. I’m sure that has more to do with our 10 cylinder SUVs than our cooking habits, but we tend to use far more than we need to no matter what it is we’re doing! –      Calvin Henry-Cotnam      | "Nothing quite livens up a suburban       DAXaCK associates       | neighbourhood like a driveway boasting Richmond Hill, Ontario, Canada | plastic milk crates loaded with crap." http://home.ica.net/~calvinhc  |   — John Oakley, radio talk-show host       NOTE: if replying by email, remove the capital letters!

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Response:

total power required derive from the room-size.  But if you wanted to quad-outlets every 16" all the way around a room, there doesn’t seem to be anything that requires you to add extra circuts to feed them. That’s a scary image :)

Not really…if you think about it. Imagine a home where every outlet was a "quad" instead of a duplex. You’d drastically cut down on the number, if not eliminate the usage of those adaptors, or those 3-into-1 extention cords when extending the cord isn’t the intended purpose, but 3-into-1 is. A 20′ x 24′ dormer extention with 3 bedrooms would only require 1 15a circuit following the current code. (20 x 24 = 480sq. ft. x 3 watts = 1440 watts, which . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Response:

Most codes require 20a for outlets but permit 15a for lighting-only circuits.  This is surprising to hear from someone who lives in NYC. New York City prohibits general-usage 20A circuits. As a casual summary, they’re allowed where the NEC mandates them (for example, the kitchen) and for dedicated circuit receptacles (for example, for an air conditioner). For the exact position of NYC, get a copy of the code from the Department of Buildings.

Why bother? NYC has officially adopted the NEC! – Hide quoted text — Show quoted text –  You can try to do general-purpose 20A circuits in a commercial space in NYC, but depending on which inspector you get, you can lose very badly. In a data center I spec’d in Manhattan with something like 2400 circuits, all the wiring is #10 with no common neutrals, so as specific circuits need to be upgraded for customer requirements, they can go up to 30A without having to run new wires in the underfloor raceway. But it was all initially built w/ 15A breakers.  I’m told Canada has a similar bugaboo about 20A – instead of the US T- blade receptacale (5-20R) the Canadian version only has the horizontal slot, so you can’t even plug a 15A device into a 20A circuit.        Terry Kennedy             http://www.tmk.com Path: lobby!ngtf-m01.news.aol.com!portc03.blue.aol.com!newsfeed.cwix.com!sjc-pe

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Response:

total power required derive from the room-size.  But if you wanted to quad-outlets every 16" all the way around a room, there doesn’t seem to be anything that requires you to add extra circuts to feed them.

That’s a scary image :)

Response:

Most codes require 20a for outlets but permit 15a for lighting-only circuits.

  This is surprising to hear from someone who lives in NYC. New York City prohibits general-usage 20A circuits. As a casual summary, they’re allowed where the NEC mandates them (for example, the kitchen) and for dedicated circuit receptacles (for example, for an air conditioner). For the exact position of NYC, get a copy of the code from the Department of Buildings.   You can try to do general-purpose 20A circuits in a commercial space in NYC, but depending on which inspector you get, you can lose very badly. In a data center I spec’d in Manhattan with something like 2400 circuits, all the wiring is #10 with no common neutrals, so as specific circuits need to be upgraded for customer requirements, they can go up to 30A without having to run new wires in the underfloor raceway. But it was all initially built w/ 15A breakers.   I’m told Canada has a similar bugaboo about 20A – instead of the US T- blade receptacale (5-20R) the Canadian version only has the horizontal slot, so you can’t even plug a 15A device into a 20A circuit.         Terry Kennedy             http://www.tmk.com

Response:

Actually, the breakers are sized to protect the wiring, not the appliance. 15 amp used for 14 gauge wires, 20 amp for 12 gauge.

Correct. On the example of the condensing (outdoor) unit: The fuses (in the outdoor disconnect) protects the unit. The circuit breaker protects the wiring.

Response:

 I’m told Canada has a similar bugaboo about 20A – instead of the US T- blade receptacale (5-20R) the Canadian version only has the horizontal slot, so you can’t even plug a 15A device into a 20A circuit.

With an exception for a specific application in commercial installations, in Canada no outlet can accept more than one type of plug. An outlet rated for a certain voltage/current can only accept that same type of plug. 20A circuits are quite rare in Canada in residential installations. In kitchens, our counter outlets must be split, so we effectively have TWO 15 A circuits feeding a single outlet, one for the top and another for the bottom. That gives you 3000 Watts per outlet, allowing you to plug your toaster AND your electric kettle (something that is rather hard to find in stores in the USA, I find) into the same outlet at the same time. —       Calvin Henry-Cotnam      | "Nothing quite livens up a suburban        DAXaCK associates       | neighbourhood like a driveway boasting Richmond Hill, Ontario, Canada | plastic milk crates loaded with crap." http://home.ica.net/~calvinhc  |   — John Oakley, radio talk-show host        NOTE: if replying by email, remove the capital letters!

Response:

separate runs.  I forget exactly how much a single outlet is rated, however if it is rated 300 watts which I believe to be true, then you could have five outlets including lights, to a 15A fuse or breaker.

Having just gone looking for this, not too long ago, I couldn’t find any such limit in the 1999 NEC.   As near as I can figure out, you need 3 watts/square foot total available power for "general lighting" which appears to include everything that’s not a kitchen appliance, and you need to have no section of usable wallspace more than 6′ from an outlet, and you can’t have more than 20A feeding a recepticle. These, working together, produce a sort of ballpark for outlets per circut, because both the number of outlets and the total power required derive from the room-size.  But if you wanted to quad-outlets every 16" all the way around a room, there doesn’t seem to be anything that requires you to add extra circuts to feed them.

Response:

Actually, the 14 gauge wire is quite a bit easier to work with. Its more flexible due to the slightly thinner conductors, making it easier to fit into the box.  There’s a small cost savings as well, but the ease of working with it rather than the small cost savings makes it more desirable where 20 amp/#12 circuits aren’t necessary. Tom

– Hide quoted text — Show quoted text – Breakers are sized to protect the wiring, not the appliances. If you have 14 gauge wire you need a 15 amp breaker.  If you have 12 gauge wire for the whole circuit then you can have a 20 amp breaker. I have an old house with mostly old wiring.  The old wiring is all 14 gauge hence the circuits are 15 amps.  The new wiring is in the kitchen, which was recently remodeled and has 20 amp outlets (with 12 gauge wiring), so your coffee maker would be plugged into a 20 A circuit in my kitchen. I imagine that the primary reason for installing a 15 A circuit today in new work would be the tiny bit of money saved by using 14 gauge wire.

Response:

If 20 A and 12 gauge is better than 15 A and 14 gauge, why not wire your house with 50 A breakers and really sleep at nite?

Good point! IMHO, except for kitchen/utility circuits, 15 A is perfectly adequate to run my table lamp and clock radio. Isn’t power consumption of most consumer appliances, computers, etc. going down, not up? Rick

I think that’s the stated goal from the PC crowd, but in reality… there’s more and more devices. – Hide quoted text — Show quoted text – It seems most home wiring is done with 14 gauge wire which is protected with 15 amp breakers/fuses.  12 gauge wire on the other hand can carry 20 amps safely, and hence 20 amp breakers/fuses.  The twenty amp circuits are usually in kitchens where toasters and the like are most likely used. If you price 12 gauge wire versus 14 gauge, you’ll find it more expensive.  In addition, it’s more difficult to work with being a heavier wire. Ace Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? — Charles If necessary to reply by email,

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Response:

I have a 1500 watt heater. When I rewired the outlet with 12ga wire to replace the 14, the output of the heater increased significantly. So now, the heat is going where I want it, instead of into the walls. I would never choose to use 14ga wire. Bob

– Hide quoted text — Show quoted text – Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? Most codes require 20a for outlets but permit 15a for lighting-only circuits. Steve Manes, Brooklyn, USA www.magpie.com What the HELL are you talking about??? NYC code? Old NYC code called for 20a outlets, and only 12ga wire for both 15 & 20a circuits. Just about every single residence ever built in the USA between 1960’s and yesterday used mostly 14ga wire on 15a circuits. 20a circuits, for appliances, air-conditioners, were the EXDCEPTION, not the rule. 14ga wire is cheaper and much easier to work with, and even today is way more than adequate for lighting & most bedroom / livingroom / den loads. I’d rather have 4 15a circuits in my home than 3 20a circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Response:

Actually, the breakers are sized to protect the wiring, not the appliance. 15 amp used for 14 gauge wires, 20 amp for 12 gauge. – Hide quoted text — Show quoted text – Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? Let’s use a hypothetical example: I got a coffee maker that pulls about 12 amps. If it decides to pull over 15 amps, I want that fuse/breaker to blow/trip. I don’t want it to wait until it gets to 20 amps before it trips. That could damage the unit and/or the wiring leading to the unit. O.K., maybe that’s not the best example, but you get the idea. Breakers are used according to what is going on the circuit. Most are 15 because you may have a group of (ceiling) lights on one or you may have a group of outlets on one. The condensing (outside) unit on a split A/C or heatpump will have a 30 amp breaker (or maybe a 60 amp on older units). If the unit calls for 30 amp (max) and you put it on a 60 amp breaker, you may burn something up (poss. your house!) if it waits until it gets to 60 amps to "break". The supply house we get our breakers from carries a lot of brands of breakers, but a quick check of their Cutler-Hammer and Square-D breakers show the 15 and the 20 amp breakers are the same price.

–      Larry Wasserman     Baltimore, Maryland

Response:

It seems most home wiring is done with 14 gauge wire which is protected with 15 amp breakers/fuses.  12 gauge wire on the other hand can carry 20 amps safely, and hence 20 amp breakers/fuses.  The twenty amp circuits are usually in kitchens where toasters and the like are most likely used. If you price 12 gauge wire versus 14 gauge, you’ll find it more expensive.  In addition, it’s more difficult to work with being a heavier wire. Ace – Hide quoted text — Show quoted text – Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? — Charles If necessary to reply by email,

Response:

If 20 A and 12 gauge is better than 15 A and 14 gauge, why not wire your house with 50 A breakers and really sleep at nite? IMHO, except for kitchen/utility circuits, 15 A is perfectly adequate to run my table lamp and clock radio. Isn’t power consumption of most consumer appliances, computers, etc. going down, not up? Rick

– Hide quoted text — Show quoted text – It seems most home wiring is done with 14 gauge wire which is protected with 15 amp breakers/fuses.  12 gauge wire on the other hand can carry 20 amps safely, and hence 20 amp breakers/fuses.  The twenty amp circuits are usually in kitchens where toasters and the like are most likely used. If you price 12 gauge wire versus 14 gauge, you’ll find it more expensive.  In addition, it’s more difficult to work with being a heavier wire. Ace Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? — Charles If necessary to reply by email,

Response:

They don’t need higher ratings to run a few light bulbs and a TV set. Your kitchen where you use several high wattage devices should be wired with #12 and 20 amp breakers. Preferably two or three separate runs.  I forget exactly how much a single outlet is rated, however if it is rated 300 watts which I believe to be true, then you could have five outlets including lights, to a 15A fuse or breaker. In my garage I run one 50 amp 220, and six 20 amp 110’s off three pieces of #02 rated much higher.  If the garage burns down I loose a car not a family. Big consideration.

– Hide quoted text — Show quoted text – Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? — Charles If necessary to reply by email,

Response:

Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? Let’s use a hypothetical example: I got a coffee maker that pulls about 12 amps. If it decides to pull over 15 amps, I want that fuse/breaker to blow/trip. I don’t want it to wait until it gets to 20 amps before it trips. That could damage the unit and/or the wiring leading to the unit.

Breakers are sized to protect the wiring, not the appliances.  If you have 14 gauge wire you need a 15 amp breaker.  If you have 12 gauge wire for the whole circuit then you can have a 20 amp breaker. I have an old house with mostly old wiring.  The old wiring is all 14 gauge hence the circuits are 15 amps.  The new wiring is in the kitchen, which was recently remodeled and has 20 amp outlets (with 12 gauge wiring), so your coffee maker would be plugged into a 20 A circuit in my kitchen. I imagine that the primary reason for installing a 15 A circuit today in new work would be the tiny bit of money saved by using 14 gauge wire.

Response:

Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? — Charles If necessary to reply by email, God forbid that you are involved in the building, construction, remodeling, designing, renovating, leasing, etc, etc, etc, of structures that are inhabited by living creatures. Or that you are are responsible for the health, life, or safety of any human beings other than yourself.

Why?  I have several 20 amp circuits in my house, especially my garage.  What exactly is wrong with my house having  20 amp breakers, #12 wire and 20 amp receptacles?

Response:

Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? Most codes require 20a for outlets but permit 15a for lighting-only circuits. Steve Manes, Brooklyn, USA www.magpie.com

What the HELL are you talking about??? NYC code? Old NYC code called for 20a outlets, and only 12ga wire for both 15 & 20a circuits. Just about every single residence ever built in the USA between 1960’s and yesterday used mostly 14ga wire on 15a circuits. 20a circuits, for appliances, air-conditioners, were the EXDCEPTION, not the rule. 14ga wire is cheaper and much easier to work with, and even today is way more than adequate for lighting & most bedroom / livingroom / den loads. I’d rather have 4 15a circuits in my home than 3 20a circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Response:

Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost? — Charles If necessary to reply by email,

God forbid that you are involved in the building, construction, remodeling, designing, renovating, leasing, etc, etc, etc, of structures that are inhabited by living creatures. Or that you are are responsible for the health, life, or safety of any human beings other than yourself.

Response:

Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost?

Most codes require 20a for outlets but permit 15a for lighting-only circuits. Steve Manes, Brooklyn, USA www.magpie.com

Response:

Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost?

Let’s use a hypothetical example: I got a coffee maker that pulls about 12 amps. If it decides to pull over 15 amps, I want that fuse/breaker to blow/trip. I don’t want it to wait until it gets to 20 amps before it trips. That could damage the unit and/or the wiring leading to the unit. O.K., maybe that’s not the best example, but you get the idea. Breakers are used according to what is going on the circuit. Most are 15 because you may have a group of (ceiling) lights on one or you may have a group of outlets on one. The condensing (outside) unit on a split A/C or heatpump will have a 30 amp breaker (or maybe a 60 amp on older units). If the unit calls for 30 amp (max) and you put it on a 60 amp breaker, you may burn something up (poss. your house!) if it waits until it gets to 60 amps to "break". The supply house we get our breakers from carries a lot of brands of breakers, but a quick check of their Cutler-Hammer and Square-D breakers show the 15 and the 20 amp breakers are the same price.

Response:

Our breakers are all 20A. 20A and 15A breakers seem to be the same price. Perhaps your house was built with sufficient separate circuits that no circuit would ever have to supply more than 15A. OTOH, I understand that many older buildings were built with wiring that *now* is rated at only 15A. Perhaps it was rated higher when it was installed. -=- Alan – Hide quoted text — Show quoted text – Why are homes typically installed with 15 amp circuits instead of 20 amp? Cost?

Response:

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