electrical outlet questions
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
Anyone remember branch circuits, that used the old porcelain knife switches with the screw in fuses;
and the porcelain main breaker that used the cartridge (30amp) type fuse?
**** and tube wiring?
Largest wire back then was 14ga.
and the porcelain main breaker that used the cartridge (30amp) type fuse?
**** and tube wiring?
Largest wire back then was 14ga.
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
Originally Posted by tjc transport
remember it?? hell, i just stripped it all out of my house when i bought the place 11 years ago. that was the power for the joint.
Our mains were 30 amps, and had three 15 amp branch circuits.
Each of the porcelain knife switches had a screw in fuse for both hot and neutral wires.
High tech, back then.
"Mifflin Clay"
Joined: Jul 2005
Posts: 3,177
Likes: 4
From: Mifflin, PA
Originally Posted by MisterCMK
Installing a 20amp receptacle on a circuit with a 15amp breaker isn't a good thing to do.
http://www.accontrols.com/Typical%20...ip%20Curve.pdf
Posting Guru
Joined: Dec 2002
Posts: 1,246
Likes: 0
From: Princeton, MN
Originally Posted by tjc transport
as a rule of choice whenever i do wiring, i will put a 15 amp breaker on a circuit with 20 amp wire, and 20 amp outlets, but not the other way.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
Originally Posted by alchymist
Actually, wont hurt anything - you can only draw 15 amps before the breaker pops. And thats steady state. Circuit breakers are strange animals - a 20 amp breaker will carry 40-50 or more amps momentarily. So the 20 amp receptacle is actually better than the 15 in this case.
http://www.accontrols.com/Typical%20...ip%20Curve.pdf
http://www.accontrols.com/Typical%20...ip%20Curve.pdf
No can do with a 15 amp breaker and 20 amp receptacles. On a 15amp circuit, you CANNOT have larger than a 15amp receptacle. With a 20amp circuit you may use 15 amp receptacles provided that it is not the only one on the circuit.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
Here is what the NEC has to say on that.
Originally Posted by NEC 2005
210.21 Outlet Devices.
Outlet devices shall have an ampere rating that is not less than the load to be served and shall comply with 210.21(A) and (B).
(A) Lampholders. Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-duty lampholder shall have a rating of not less than 660 watts if of the admedium type, or not less than 750 watts if of any other type.
(B) Receptacles.
(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
Exception No. 1: A receptacle installed in accordance with 430.81(B).
Exception No. 2: A receptacle installed exclusively for the use of a cord-and-plug-connected arc welder shall be permitted to have an ampere rating not less than the minimum branch-circuit conductor ampacity determined by 630.11(A) for arc welders.
FPN: See the definition of receptacle in Article 100.
(2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).
Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle
Circuit Rating
(Amperes) Receptacle Rating
(Amperes) Maximum Load
(Amperes)
15 or 20 15 12
20 20 16
30 30 24
(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or where larger than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.
Exception No. 1: Receptacles for one or more cord-and-plug-connected arc welders shall be permitted to have ampere ratings not less than the minimum branch-circuit conductor ampacity permitted by 630.11(A) or (B) as applicable for arc welders.
Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.30(C).
Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits
Circuit Rating
(Amperes) Receptacle Rating
(Amperes)
15 Not over 15
20 15 or 20
30 30
40 40 or 50
50 50
(4) Range Receptacle Rating. The ampere rating of a range receptacle shall be permitted to be based on a single range demand load as specified in Table 220.55.
Outlet devices shall have an ampere rating that is not less than the load to be served and shall comply with 210.21(A) and (B).
(A) Lampholders. Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-duty lampholder shall have a rating of not less than 660 watts if of the admedium type, or not less than 750 watts if of any other type.
(B) Receptacles.
(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
Exception No. 1: A receptacle installed in accordance with 430.81(B).
Exception No. 2: A receptacle installed exclusively for the use of a cord-and-plug-connected arc welder shall be permitted to have an ampere rating not less than the minimum branch-circuit conductor ampacity determined by 630.11(A) for arc welders.
FPN: See the definition of receptacle in Article 100.
(2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).
Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle
Circuit Rating
(Amperes) Receptacle Rating
(Amperes) Maximum Load
(Amperes)
15 or 20 15 12
20 20 16
30 30 24
(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or where larger than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.
Exception No. 1: Receptacles for one or more cord-and-plug-connected arc welders shall be permitted to have ampere ratings not less than the minimum branch-circuit conductor ampacity permitted by 630.11(A) or (B) as applicable for arc welders.
Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.30(C).
Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits
Circuit Rating
(Amperes) Receptacle Rating
(Amperes)
15 Not over 15
20 15 or 20
30 30
40 40 or 50
50 50
(4) Range Receptacle Rating. The ampere rating of a range receptacle shall be permitted to be based on a single range demand load as specified in Table 220.55.
"Mifflin Clay"
Joined: Jul 2005
Posts: 3,177
Likes: 4
From: Mifflin, PA
Originally Posted by MisterCMK
No can do with a 15 amp breaker and 20 amp receptacles. On a 15amp circuit, you CANNOT have larger than a 15amp receptacle. With a 20amp circuit you may use 15 amp receptacles provided that it is not the only one on the circuit.
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Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Actually, the NEC, as Chris has been pointing out, is pretty clear about what is permitted and what is not.
A 20 A receptacle (typically a NEMA 2-20R, 5-20R, or a 6-20R), if placed on a 15A protected branch circuit, would invite placing a load on the circuit that is greater than the rated protection, usually resulting in the breaker or fuse letting go.
NEC Table 210.21(B)(3) specifically PROHIBITS putting a 20A receptacle on a 15A branch circuit.
The standard receptacles used in 99% (or more) of the households in North America are NEMA 5-15R receptacles which are rated for 15A. The 20A NEMA 5-20R receptacle, if used, will accept all common 15A 5-15P plugs. However, if used, it must still be used on a 20A branch circuit.
A handy reference for common NEMA configurations is at http://nooutage.com/nema_configurations.htm
A single receptacle on a branch circuit cannot be less than the branch circuit rating.
Steve
A 20 A receptacle (typically a NEMA 2-20R, 5-20R, or a 6-20R), if placed on a 15A protected branch circuit, would invite placing a load on the circuit that is greater than the rated protection, usually resulting in the breaker or fuse letting go.
NEC Table 210.21(B)(3) specifically PROHIBITS putting a 20A receptacle on a 15A branch circuit.
The standard receptacles used in 99% (or more) of the households in North America are NEMA 5-15R receptacles which are rated for 15A. The 20A NEMA 5-20R receptacle, if used, will accept all common 15A 5-15P plugs. However, if used, it must still be used on a 20A branch circuit.
A handy reference for common NEMA configurations is at http://nooutage.com/nema_configurations.htm
A single receptacle on a branch circuit cannot be less than the branch circuit rating.
Steve
Last edited by projectSHO89; Oct 31, 2007 at 08:26 AM.
Post Fiend
Joined: Apr 2004
Posts: 6,473
Likes: 4
From: Lafayette, IN
Some here on this thread KNOW what they are talking about, some DO NOT. Who are you going to trust with your life?
I've been around enough electricians in construction and asked enough questions, and read enough of the NEC to know that there is some definite misinformation in this thread.
1. The circuit breaker protects the WIRING ONLY. Therefore, they must be matched, except that the wire ampacity can exceed the breaker rating (i.e., you can use a 15A breaker with 12-ga wire, in some cases you must for long runs or other derating scenarios). You cannot go the other way around--14-ga wire (usually 15A ampacity) on a 20A breaker.
2. A 20A circuit (20A breaker and 12-ga wire) may have multiple 15A outlets, whether a single 15A duplex receptacle or multiple single receptacles (branch circuit), but it may not have only a single 15A receptacle (individual circuit).
3. Mis-wiring hots and neutrals, while it may work electrically, is unsafe. That's why most plugs on electrical products today have "polarized" blades--one blade is larger than the other.
Jason
On edit: You really should, if you have ANY doubts whatsoever, consult a local electrician who knows the local code. Most places use a version of the NEC, but some places add to it or use a different code set altogether.
I've been around enough electricians in construction and asked enough questions, and read enough of the NEC to know that there is some definite misinformation in this thread.
1. The circuit breaker protects the WIRING ONLY. Therefore, they must be matched, except that the wire ampacity can exceed the breaker rating (i.e., you can use a 15A breaker with 12-ga wire, in some cases you must for long runs or other derating scenarios). You cannot go the other way around--14-ga wire (usually 15A ampacity) on a 20A breaker.
2. A 20A circuit (20A breaker and 12-ga wire) may have multiple 15A outlets, whether a single 15A duplex receptacle or multiple single receptacles (branch circuit), but it may not have only a single 15A receptacle (individual circuit).
3. Mis-wiring hots and neutrals, while it may work electrically, is unsafe. That's why most plugs on electrical products today have "polarized" blades--one blade is larger than the other.
Jason
On edit: You really should, if you have ANY doubts whatsoever, consult a local electrician who knows the local code. Most places use a version of the NEC, but some places add to it or use a different code set altogether.
Last edited by jroehl; Oct 31, 2007 at 08:42 AM.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
Originally Posted by jroehl
3. Mis-wiring hots and neutrals, while it may work electrically, is unsafe. That's why most plugs on electrical products today have "polarized" blades--one blade is larger than the other.
Logistics Pro
Joined: Nov 2004
Posts: 4,562
Likes: 2
From: Southern MD
Originally Posted by MisterCMK
Good info that hasn't been mentioned yet. For those of you that don't know, ALWAYS switch the hot and NOT the neutral. Bad bad bad bad idea to switch the neutral.
Lots of good information in this thread!!!!!!!!!
Kudos to all that have posted their knowledge!
My dear old Dad had an electrical issue at his house several years ago, where the lights in several rooms just stopped working.
(No circuit breakers thrown, etc.)
After tracing the wiring back to a junction box in the basement, I discovered that Dad had changed one of the 'pull chain' lights in his workshop to a switched light.
He had put the switch across the neutral and also hadn't used a big enough wire nut, causing the circuits to 'open'.
There was also evidence of 'arcing' in the box.
Needless to say, my dear old Dad doesn't do any more wiring. (I'm surprised he didn't try to put the switch across the 'ground', considering he has been recently diagnosed with Alzheimer's!)
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Here's a little memory aid that helped me remember which colored wire goes where on receptacles and plugs.
The German word for "wide" is "weit" (pronounced "vite"). It happens to sound very much like "white" and ryhmes mostly with "wide". All ties together.
Steve
The German word for "wide" is "weit" (pronounced "vite"). It happens to sound very much like "white" and ryhmes mostly with "wide". All ties together.
Steve
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
One more thought. If anybody has any question or hesitation when working with electricity whether it is line voltage or low voltage, ASK! Always be sure that you know exactly what you are doing. I know that there are many people on here who are more than willing to try and help you (myself included especially when it comes to low voltage) but also don't be afraid to call an electrician or the city inspector and ask your question. Don't take shortcuts.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
Originally Posted by alchymist
Never said you could or couldn't do it, I said it wouldn't hurt anything..............as opposed to a 15 amp receptacle on a 20 amp breaker........
If you install a 20amp receptacle on a 15amp circuit you are inviting an overloaded circuit.