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Why Can't I Use 20 amp Outlet On 15 amp Line?

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46K views 49 replies 24 participants last post by  taglicious  
T
#1 · (Edited)
Why won't the code allow me to put a 20 amp outlet on a 15 amp line? From electrician videos that I've watched on youtube, the 20 amp outlets seem better made and more robust (and therefore safer). ***Edit....additional citation:
Table 210.21(B)(3)

I can't find the answer anywhere, but I'm guessing it's because if someone took the cover off the outlet and examined it, they might assume that the wiring was for 20 amp. when it was only for 15 amp.

Thanks in advance for any comments.

Tryingtofixit (newbie to home repair)
 
#2 ·
Tryingtofixit said:
Why won't the code allow me to put a 20 amp outlet on a 15 amp line? From electrician videos that I've watched on youtube, the 20 amp outlets seem better made and more robust (and therefore safer).

I can't find the answer anywhere, but I'm guessing it's because if someone took the cover off the outlet and examined it, they might assume that the wiring was for 20 amp. when it was only for 15 amp.

Thanks in advance for any comments.

Tryingtofixit (newbie to home repair)
Click to expand...

I believe there is the thinking that if there were a 20 amp appliance that would fit into a 20 amp receptacle that is on a 15 amp circuit that the circuit would be overloaded.

Btw, if you are not an electrician then we cannot answer diy questions. You screen name appears as a non-electrician. You can go and post at diychatroom.com.
 
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T
#10 ·
Thanks for your response!!!
Regarding your last comment...
"Anyone who works...in a related professional electrical field is welcome to join this website and participate in our forums." Who's Allowed to Join ElectricianTalk.com
I have been a federally licensed amateur radio operator (ham) for approximately 20 years who volunteers putting up temporary communication stations together in weather-related emergencies. Some of my work involves repairing or modifying high voltage tube equipment (mostly transmitters).
I was just wondering if electricians agreed with my thoughts about the code rule.
 
T
#9 ·
John Valdes said:
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"Anyone who works...in a related professional electrical field is welcome to join this website and participate in our forums." Who's Allowed to Join ElectricianTalk.com
I have been a federally licensed amateur radio operator (ham) for approximately 20 years who volunteers putting up temporary communication stations together in weather-related emergencies. Some of my work involves repairing or modifying high voltage tube equipment (mostly transmitters).
I was just wondering if electricians agreed with my thoughts about the code rule.
 
#7 ·
Tryingtofixit said:
Why won't the code allow me to put a 20 amp outlet on a 15 amp line? From electrician videos that I've watched on youtube, the 20 amp outlets seem better made and more robust (and therefore safer).

I can't find the answer anywhere, but I'm guessing it's because if someone took the cover off the outlet and examined it, they might assume that the wiring was for 20 amp. when it was only for 15 amp.

Thanks in advance for any comments.

Tryingtofixit (newbie to home repair)
Click to expand...
Since it isn't' locked yet I will answer.
A 15 amp breaker will hold a 20 amp load for a certain amount of time, so if you plug 20 device load in it will run for awhile. It is enough time to start wire insulation breakdown and if you repeat enough you will get a failure.
The proper load in the proper place with proper protection will not do this.
 
V
#12 ·
There are code rules in the Canadian Electrical Code (and I'm assuming similar in the NEC) that state the receptacles must be installed on a matching power source (voltage and amperage).

The reason is so connected things work properly and safely. Look up "NEMA receptacle charts" and you will there are many different receptacles out there for specific uses. It doesn't make sense to put a 50A receptacle on a 15A circuit 'just because' you happen to have it around. You won't be able to use it properly.

The 125V 20A receptacles you are talking about are a little bit of a cheat, in that they will still accept a 15A plug if they have that T slot on them. There is also a 20A receptacle that doesn't have the T, that will only accept a 20A plug.

A 20A outlet on a 15A circuit will not cause a fire. The 15A breaker will protect the wire, just like if you plugged in 2 separate devices at the same time that overload the circuit. What it can do is cause frustration if people(say the next owner of the house) think they can plug in a 20A device, but it won't work, so they up the breaker to 20A, and then burn the house down.
 
N
#15 ·
As others said, there are plenty of better than resi grade 15 amp receptacles. That said terminated correctly and replaced when they no longer hold the blades of a plug well, they are fine. Not many times you need the 20 amp configuration anyway. Maybe a wood shop? Garage tools, small welder. For the most part, a 15 is suitable.
 
#20 ·
I don’t even believe I have ever seen an air conditioner that had the 20 amp 125 V blade. It seems all air conditioners are sold with a standard 15 amp U blade configuration, and from there they go to 240 V anyway.
 
#26 ·
I've seen 15A receptacles on 15A circuits melt. They're just built like that.
You can't use a 20A on a 15A circuit because it indicates to people that they can plug 20A devices into it. Otherwise, the internals are identical.
That's it. I'm sure this was solved somewhere in the distant past when the thread was made...
 
P
#36 ·
Complete disagreement with inspectors here. This is definitely a "show me the Code" type situation and this is what it is.

Say I don't have any 3/0 cable but I've got some 4/0 cable left over from another job. If the ampacity calls for 3/0 do I HAVE to use 3/0 or is it acceptable to over-rate equipment? By the same token, Code specifies MAXIMUM ratings for fuses and circuit breakers. There is NO Code limitation on using an "undersized" breaker if you chose to do so for whatever reason. This isn't the same as under-dutied. For instance Code specifies a maximum of 175% of currrent rating for fuses for motors. There's nothing wrong with using 150% rating and many people actually do that.

As Mike Holmes would say, "minimum Code standard" is often not acceptable. You're putting in a better receptacle, same as my example of using 4/0 where 3/0 is acceptable, or using 150% rated fuses on motors where 175% is acceptable. There is nothing in Code that says you can't put in something larger than what you need. That is not for the inspector to decide. Their job is to enforce minimum Code standards.
 
K
#38 ·
If somebody sees a 20 amp receptacle they might think it is OK to plug in a 20 amp load not realizing it is only 15 amps. Yes the 15 amp breaker should trip but the customer will be at a loss. It is the configuration that makes it a 20 amp. Besides the NEC does not allow you to do what the OP wants.
 
#44 ·
I was pretentious about receptacles early on. I figured my electrons were tuffer than other peoples and I needed better connections.
I was getting regrouped in a new building and needed a lot of stuff and the box stores were just starting and these were lower shelf even at HWD stores, we thought maybe ok and we will upgrade for some heavy spots. 30 yrs later in heavy duty shop and they are still working and cannot ever recall replacing a failed one,,, never replaced one used as replacement for old USA.
I replaced 1 or 2 in a well pit or were under leaking covers and chased out a cord end that was causing a problem, while back simply went direct vs an appliance cord I bought for the chore, recept cooled and didnt even change it. I have replaced a couple were hit with a hammer, that stuff doesnt count.
I am strong, tightening the screws isnt a problem and snug and resnug as boxes being packed or in shop use stranded wire. I have 3 dozen in the ceilings all they ever see is 1 fixture.
 
#48 ·
Thhn #14 guage wire is rated at 20 amps. There are code restrictions on it's use on 20 amp circuits however, but the fact of it's 20 amp rating still stands. Most of the talk in this thread about breakdown of the insulation is horseshirt in this one particular case.

That's right fella's, macmikeman said it............
 
K
#49 ·
macmikeman said:
Thhn #14 guage wire is rated at 20 amps. There are code restrictions on it's use on 20 amp circuits however, but the fact of it's 20 amp rating still stands. Most of the talk in this thread about breakdown of the insulation is horseshirt in this one particular case.

That's right fella's, macmikeman said it............
Click to expand...
Years ago in the days of plug fuses, they used 30 amp fuses on 14 wire. If they did not have a 30 amp then they put a penny in the socket then screwed in the 15 amp fuse.
 
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