Dryer Outlet

[charlie b]

What is the NEMA configuration for a standard household dryer plug / receptacle? I have a NEMA chart, but I don't see a configuration for a 2-pole, plus neutral, plus ground. Do they use a 3-phase configuration, and repurpose the four slots for a single phase, 120/240V plus ground?


By the way, this is not a DIY project. I am doing the electrical design for a high-end dwelling unit. I need to show the outlet configuration on the floor plan.

 

[1793]

What is the NEMA configuration for a standard household dryer plug / receptacle? I have a NEMA chart, but I don't see a configuration for a 2-pole, plus neutral, plus ground. Do they use a 3-phase configuration, and repurpose the four slots for a single phase, 120/240V plus ground?


By the way, this is not a DIY project. I am doing the electrical design for a high-end dwelling unit. I need to show the outlet configuration on the floor plan.

Is this what you're looking for? -- NEMA 14-30R

 

[charlie b]

My chart lists that one under "3-pole, 4-wire, grounding." So is the answer to my previous question (about using a 3-phase configuration for a single phase application) "yes"?

 

[Ponchik]

View attachment 13886
NEMA 14-30R

 

[Ponchik]

My chart lists that one under "3-pole, 4-wire, grounding." So is the answer to my previous question (about using a 3-phase configuration for a single phase application) "yes"?

It looks like a 3 phase 4 wire is different than a 3 pole 4 wire.

The 3 phase receptacle has a different configuration than that of what is generally used on residential dryer receptacle.

I will try to post a picture.

 

[Ponchik]

View attachment 13887

 

[JFletcher]

That plug (14-30R) could not be used for 3ph; you'd need one like this with a different pinout:

http://www.stayonline.com/detail.aspx?id=7072

 

[charlie b]

Thanks, everyone.

 

[norcal]

View attachment 13886
NEMA 14-30R

There are folks who use that receptacle for 3 phase. :happysad: Same with locking 4-wire 125/250V devices, both annoy me as there are all those configurations with different voltage/ ampere/# of phases for a reason.

 

[kwired]

There are folks who use that receptacle for 3 phase. :happysad: Same with locking 4-wire 125/250V devices, both annoy me as there are all those configurations with different voltage/ ampere/# of phases for a reason.

If you look at the price and availability of one designated for three phase you will understand the temptation:happyyes:

 

[FionaZuppa]

what about nema 14-50R/P ??

 

[iwire]

what about nema 14-50R/P ??

That would be for a 50 amp circuit not a 30 amp circuit.

 

[kwired]

14-30 and 10-30 are most commonly used for electric clothes dryers.

I suppose if you had a dryer that didn't utilize a neutral you could use a 6-30 but most still use one of the other two because they are considered standard for that appliance.

10 -30 is considered three pole non grounding 125/250 volts
14- 30 is considered three pole 4 wire 125/250 volts (with ground)
6 -30 is considered two pole 3 wire 250 volts (with ground)

 

[FionaZuppa]

That would be for a 50 amp circuit not a 30 amp circuit.

sure, so any of the nema 14- R's would be the line to be in, choose the -xx that meets the requirements of the load. the appliance installer will need to provide the correct plug. most dryer install docs say "minimum 240ac 30A" and reference 14-30R. is having 14-50R with properly sized wiring w/ 30A ocpd not allowed by NEC ? but, 14-30R seems to be the std/norm for new wire.

14-30 and 10-30 are most commonly used for electric clothes dryers.

I suppose if you had a dryer that didn't utilize a neutral you could use a 6-30 but most still use one of the other two because they are considered standard for that appliance.

10 -30 is considered three pole non grounding 125/250 volts
14- 30 is considered three pole 4 wire 125/250 volts (with ground)
6 -30 is considered two pole 3 wire 250 volts (with ground)

??

14- are all 2-pole that include a N and G connection. not sure why they call them 3-pole as that seems to indicate 3-phase.

 

[iwire]

14-30 and 10-30 are most commonly used for electric clothes dryers.

I suppose if you had a dryer that didn't utilize a neutral you could use a 6-30 but most still use one of the other two because they are considered standard for that appliance.

10 -30 is considered three pole non grounding 125/250 volts
14- 30 is considered three pole 4 wire 125/250 volts (with ground)
6 -30 is considered two pole 3 wire 250 volts (with ground)

In my opinion the 10-30 is the correct choice for existing installations as there is no grounding conductor in those old circuits, only two hots and a neutral.

I wonder if there is any other legal use of a NEMA 10 now other than existing ranges and dryers?

 

[FionaZuppa]

In my opinion the 10-30 is the correct choice for existing installations as there is no grounding conductor in those old circuits, only two hots and a neutral.

I wonder if there is any other legal use of a NEMA 10 now other than existing ranges and dryers?

its new wire, has to be 14-
if its a old dryer being used with a 3 wire plug, then the R has to be a 14- and the plug needs to be replaced.

a nema L14-30 would also be acceptable.

 

[iwire]

its new wire, has to be 14-

I agree.

if its a old dryer being used with a 3 wire plug, then the R has to be a 14- and the plug needs to be replaced.

Yes.


But that does not change the fact a 14-50 would be inappropriate for a 30 amp dryer circuit.

 

[FionaZuppa]

But that does not change the fact a 14-50 would be inappropriate for a 30 amp dryer circuit.

in what sense?

A key point to remember about branch circuits is that the overcurrent protection device (OCPD) defines the circuit. Thus, the rating of the OCPD determines the rating of the branch circuit; the conductor size does not [210.3].

30A ocpd with 30A wire that ends on a 14-50R ? is that not allowed?
or
30A ocpd with 50A wire that ends on a 14-50R ? is that not allowed?

dryer install docs usually say "minimum 30A". does 125% rule apply?

and from what i can see, 14-50R meets the NEC requirement that receptacle be rated not less than ocpd. but if you ran 30A wire i see no need for a -50R, but, i might run 50A wire w/ -50R and use 30A ocpd. all depends on where that R is physically located (near garage, upstairs, etc), never know when you might need to upgrade to 50A (if ever a possibility based on location)

 

[iwire]

in what sense?

In the sense of poor design and a code violation.

See 'Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits'

 

[FionaZuppa]

In the sense of poor design and a code violation.

See 'Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits'

isnt that a max load table? for cord-&-plug max load on a 30A ocpd = 24A. NEC states that receptacles not be rated less than OCPD. at 24A max is that enough for a dryer where install doc says "min 30A" ? i suspect that min means OCPD, but can you give clarity.