Does a 20A plug fit in a 30A recepacle

[bcorbin]

I asked a contractor I work with a lot if he knew some way I could learn more about the physical guts of wiring a building (I'm another dumb Engineer :grin: ). He told me they're doing a Habitat Home in the Spring, and they'd love to see me sweat a little. I really can't wait. The only bad part is... even though I can do imaginary math, I'm not gonna be allowed to do much more than be a laborer. I just hope to soak some of it up by watching.

 

[allenwayne]

One question has puzzled me for some time, central vacuum systems.I have been speced many time a 30 amp circuit for them.So #10 is run, but on trim out they come with a 20 amp cord cap?????? The unit says MOCPD as 30 but the cord cap is a 20 amp plug.How can this be UL listed ?????

 

[jwelectric]

One question has puzzled me for some time, central vacuum systems.I have been speced many time a 30 amp circuit for them.So #10 is run, but on trim out they come with a 20 amp cord cap?????? The unit says MOCPD as 30 but the cord cap is a 20 amp plug.How can this be UL listed ?????

I can?t help but wonder if that vacuum works with a motor and if so if the overcurrent device would be sized from Table 430.52. What do you think?

 

[allenwayne]

I can?t help but wonder if that vacuum works with a motor and if so if the overcurrent device would be sized from Table 430.52. What do you think?

Well we all know that the vacuum does use a motor and that there has to be a start up window.But wouldn`t you think that there has to be a continuous load scenario somewhere.......My whole point is that if there is a cord cap/receptacle on a 30 amp circuit then the same assembly has to be rated at 30 amps.But they come with 20 amp plug ins.???????

 

[zbang]

One way to be absolutley certain that your customers cannot jam a 20 into a 30 is to use twist lock receptacles.

Since it's popped up again, using a twistlock doesn't always help. I've seen people successfully insert a L6-20 into an L6-30R. You bend the blades a little, but it does "work". Not that I recommend it. It becomes really amusing when you have to make -20 to -30 adapters for temp/emergency installations (What's with these all one foot extensions?).

 

[steve66]

Old threads never die. Sheesh, after 3 years Makes you realize how much (or how little) you've learned. :smile:

 

[celtic]

Sheesh, after 3 years Makes you realize how much (or how little) you've learned. :smile:

See below

​

 

[Dennis Alwon]

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.

Bob I am confused again--- Suppose these vending machines are not single receptacles but rather 6 or so that are feed from a 10 gauge wire on a 30 amp breaker. If the load of the machines totaled do not exceed 30 amps then why can't you use 20 amp receptacles to feed them. We use 15 amp receptacles on 20 amp circuits all the time.

 

[tallgirl]

I asked a contractor I work with a lot if he knew some way I could learn more about the physical guts of wiring a building (I'm another dumb Engineer :grin: ). He told me they're doing a Habitat Home in the Spring, and they'd love to see me sweat a little. I really can't wait. The only bad part is... even though I can do imaginary math, I'm not gonna be allowed to do much more than be a laborer. I just hope to soak some of it up by watching.

Contact your local state licensing board and see about getting an apprentice license. Then you can show up on the jobsite, flash your apprentice card, and insist on doing something other than pounding nails into a board. You can, uh, pound nails on junction boxes into boards. Yeah, that's the ticket.

My efforts with HfH are apparently going to be featured in my site's monthly newsletter. I was asked what skills I use on the job are used working with HfH. I wrote --

For (division name) I pound on keyboards and mess with wires. For Habitat and Common Ground Collective I pound on nails and mess with wires. Beyond the pounding and the wires, there are no similarities. I make use of my leadership skills and other soft-skills I've learned at (employer name), but there are no computers, no networks, no Powerpoint presentations and no conference calls -- and that's a good thing.

You'll enjoy Habitat. Cheaper than working out at the gym, and better for the karma.

 

[tallgirl]

Bob I am confused again--- Suppose these vending machines are not single receptacles but rather 6 or so that are feed from a 10 gauge wire on a 30 amp breaker. If the load of the machines totaled do not exceed 30 amps then why can't you use 20 amp receptacles to feed them. We use 15 amp receptacles on 20 amp circuits all the time.

'Cuz the code sez you can't. Look at tables 210.21 (B) (2) and (B) (3). A 30A BC has to have 30A receptacles. A 20A BC can have either 15A or 20A.

 

[Dennis Alwon]

'Cuz the code sez you can't. Look at tables 210.21 (B) (2) and (B) (3). A 30A BC has to have 30A receptacles. A 20A BC can have either 15A or 20A.

Thanks. I knew I missed something.

 

[bjp_ne_elec]

The NEMA link doesn't work. Anybody have a link to check out configurations?

 

[Jim W in Tampa]

You could install a 30 amp receptacle and tell customer to stop at the RV store for an adapter.No idea how they can sell such stuff but they do

 

[George Stolz]

The NEMA link doesn't work. Anybody have a link to check out configurations?

https://www.hubbellnet.com/max_htm/tech_stuff/NEMA/front.html

Google is my friend.

 

[Dennis Alwon]

https://www.hubbellnet.com/max_htm/tech_stuff/NEMA/front.html

Google is my friend.

Google is my friend too George
http://nooutage.com/nema_configurations.htm

 

[George Stolz]

All right, so yours was better. So what?

( :smile: )

I do like this picture, very easy to see.