Does a 20A plug fit in a 30A recepacle

[steve66]

I have had clients ask for 30A branch circuits and 30A receptacles for general use. If I give them 30A receptacles, will a standard 15 or 20 amp plug fit into the receptacle?

In other words, will a NEMA 5-15 plug or a NEMA 5-20 plug work with a NEMA 5-30R receptacle? Looking at exhibit 406.2, it looks like the answer would be no, but I want to be sure before I tell someone a 30A outlet won't work.

Steve

 

[kiss]

Re: Does a 20A plug fit in a 30A recepacle

It will NOT FIT.

 

[iwire]

Re: Does a 20A plug fit in a 30A recepacle

No, a 20 amp male cord cap will not fit a 30 amp female outlet.

Go here for the NEMA chart of outlets.

No, you may not feed 20 amp outlets with a 30 amp branch circuit.

Take a look at Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits

They may think they need 30 amp GP outlets when really what they need is more 20 amp GP outlets.

 

[steve66]

Re: Does a 20A plug fit in a 30A recepacle

Good link Iwire. Thanks.

No, you may not feed 20 amp outlets with a 30 amp branch circuit.

I am aware of that. However, I am doing a design where I am moving some vending machines. Unless the machines have 30A plugs, 20A receptacles on a 30A branch circuit is just what was already there.

Steve

 

[jimwalker]

Re: Does a 20A plug fit in a 30A recepacle

Then you need to replace that 30 breaker with a 20.The #10 wire (assuming thats what they ran) can stay.Maybe they were tripping a 20 and there in house man FIXED it, by putting in a 30.

 

[Guest]

Re: Does a 20A plug fit in a 30A recepacle

I find it difficult to believe you are a building wiring engineer and dont know the difference between 15, 20, and 30 amp out lets. Why do you suppose they are all made differently.? Sorry to be so judgemental but it sounds to me like all of youe engineering experienc comes from a book.

 

[steve66]

Re: Does a 20A plug fit in a 30A recepacle

Joe:

In my defense:

I do know the difference between 15, 20 and 30 Amp outlets. A 15A plug goes into a 20 A receptacle, so it stands to reason that a 20A might go into a 30A receptacle. That's why I asked. And if you look at exhibit 406.2 like I mentioned earlier, it does look like a 20A plug has the right orientation to fit into a 30A receptacle.

I was pretty sure that wouldn't work, but I wanted to be absolutely sure before I told a client that it wouldn't work. So I was mostly just being cautious.

I can assure you I have more hands on experience than most engineers. But, that doesn't really matter.

Now forgetting the receptacle; I take exception to your idea that something learned from a book isn't as good or real as something you learned in the field.

I think it is obvious that any engineer doesn't have the hands-on that an electrician will have. So it is easy for electricians to tell engineers "everything you know came from a book". However, electricians and engineers have different jobs. I realize that as a electrician, what you learn from a book won't finish the job at the end of the day. But for my work, field experience usually isn't much help. Things I have learned from books is mostly what I need. Calculations and that type of thing.

Steve

 

[jimwalker]

Re: Does a 20A plug fit in a 30A recepacle

Steve, not trying to sound like a wise a$$ but maybe engineers should be required to spend at least a year in the field with both com.and residential to get an idea of actual work conditions.Very easy to just draw circuits and outlets but installing is completely different.

 

[Guest]

Re: Does a 20A plug fit in a 30A recepacle

You are somewaht correct however field experience would help you immensly when it comes to recognizing things you see in a book. You say you looked in a book at the configurations of 20 and 30 amp plugs eh? Take another close look and you will see that the ground prong on the 20 is oriented tatally the opposite of a 30, hence it wont friggin fit!!!As you see you must be careful with what you get from a book too.

 

[roger]

Re: Does a 20A plug fit in a 30A recepacle

Don't worry about it Steve, there may be some jealousy in some of the posts in this thread. If all engineers were electricians too, the complainers would still complain.

Roger

 

[steve66]

Re: Does a 20A plug fit in a 30A recepacle

Jim:

I believe I do my job just fine without a year of field experience. (Actually, I'm not the best person to argue this because I did have a year of experience as an electrician - industrial actually- and more experience as a technician).

I think you and Joe would be just as defensive if I suggested electricians be required to take a year and set a a desk and learn how to do engineering calculations. (I know the apprentiship program does include a lot of "book learning" and math, ect, but think about spending an extra year on top of that learning stuff you won't really use).

And I could easily page through past threads and find places to shout "that electrican just needs to sit down and study the codes!!" But electricians don't have the time to sit and study dozens of books any more than I have the time to learn about all the finer points of running conduit.

I guess my point is that you're free to complain about engineers all you want, but you guys frequently have to work with us, and you're just going to have to live with us the way we are

 

[steve66]

Re: Does a 20A plug fit in a 30A recepacle

Joe:

Are we looking at the same receptacle, Nema 5-20 and 5-30? The ground looks the same in both cases. Small round pin. On top in both cases. Or if you meant the neutral pin, I could visualize the L shape accepting either a horizontal or vertical blade.

By the way, when is the last time you actually installed one of these? I think you have to admit 30A receptacles aren't the most common items to install. I had actually gone to the local hardware store to pull one off the shelf and answer my own question, and they didn't even have any. They had lots of non-NEMA 30A receptacles (for motor homes I think), but not any NEMA 5-30 outlets or plugs.

Steve

 

[engy]

Re: Does a 20A plug fit in a 30A recepacle

By blade configuration it would seem to work, but there is a physical size difference going from 15/20A to 30A.

When I was a master electrician, I wasn't impressed by engineers who thought they knew everything.

As an engineer, I am not impressed by electricians who think they know everything.

Why can't we just get along?

 

[jimwalker]

Re: Does a 20A plug fit in a 30A recepacle

Thing is that if the electrician follows the engineer drawings and there is a problem it will be at his expense to fix it not the engineers.

 

[roger]

Re: Does a 20A plug fit in a 30A recepacle

Not true Jim. If it is truly an engineering mistake it will not be your cross to bear.

If it's a code or installation problem you should have caught and brought to the engineers attention, (after all licensed electricians or companies are supposed to be competent) then you should fix it at your expense.

I've seen to many installers that have the attitude "the engineer drew it and I'm going to install it that way come hell or high water".

After you write an RFI and the engineer still instructs you to do it wrong, then at that point in time you have done what you could do and the burden is his.

Roger

[ February 09, 2004, 03:04 PM: Message edited by: roger ]

 

[Guest]

Re: Does a 20A plug fit in a 30A recepacle

Steve we indeed asre I believe looking at the same receptacle. or plug Thge nema 5-20r has a neutral blade with a small right angle to the right located in the center of the neutral blade. The nema 5-30r has a smal right angle at the top of the neutral bar. They are also different in physical size. Did not mean to demean or offend . Sorry Joe

 

[Guest]

Re: Does a 20A plug fit in a 30A recepacle

Also the small projection points to the left

 

[steve66]

Re: Does a 20A plug fit in a 30A recepacle

Joe:

The L shaped slot on the 5-30 looked like it just might be made to accept the horizontal 20A neutral blade or the vertical 15A blade. Somewhere during this thread I did realize the 30A must be physically larger.

You didn't offend me at all. I enjoyed discussing the differences in training for electricians and engineers and hearing Jim's suggestion. I thought the thread kept a very friendly tone.

Steve

 

[Guest]

Re: Does a 20A plug fit in a 30A recepacle

One way to be absolutley certain that your customers cannot jam a 20 into a 30 is to use twist lock receptacles. This makes it idiot proof unless they alter the plug with a pair if dykes.

 

[jimwalker]

Re: Does a 20A plug fit in a 30A recepacle

If there gonna put a 20 amp plug into a 30 amp receptacle i want to watch,should be lots of fun :roll: Go ahead and give them tools