Cords, plugs and sockets for 20A, 120V service

[RichBenn]

I'm doing a two element 120V build on two separate 20A GFCI circuits. I'm struggling with finding 20A rated plugs and cord and having some difficulty understanding what NEC requires. Here are some questions:

1. The wall bathroom and kitchen GFCI sockets that are rated for 20A do not have the horizontal blade that one will find on 20A rated plugs. Do I need to use an adapter?

2. I thought about hacking up 12/3 heavy duty extension cords, but it appears none of them are rated for 20A. Is that because of the plug only?

3. I did find some 20A rated 12/3 SJOOW Jacket cord (for about $65/50 feet) if I can't use extension cord. Anyone know of cheaper sources? (I need about 25 feet)

4. It's confusing that 20A breakers are used on circuits with 15A sockets, but that's what I'm seeing in my house in some locations. Can anyone with a codebook or code knowledge shed some light on this? Seems wrong to me. Wiring is 12 guage, but I don't get the socket thing, unless the inspector missed the fact that the breaker was 20A and not 15A. In fact, the whole plug/socket thing for 20A is a bit confusing for me.

 

[bberr004]

Unfortunately, I do not have an answer for you - but I am wondering the same thing. I am currently using a 12/3 extension cord like this one for my manual controlled 2000w element. The cord/connectors never even get warm (unlike when I use a cheaper "light duty cord"). Although it is not technically rated for 20A, it seems to have no trouble with my element. I am wondering if the amperage rating is more of a legal issue regarding the type of connector more than a safety issue (to prevent people from overloading cheap cords). As long as you are using heavy duty type connectors instead of the cheapo ones I would think you should be OK. I am in the process of adding a pid and redesigning my system now and it seems to be hard to find information about this.

 

[grandequeso]

the electrical code allows you to put 15a rated receptacles on a circuit rated for 20a. It allows this because you're not likely to plug one thing in that has that much of a load into one outlet. 20amp rated receptacles shouldn't be too difficult to find. If your hardware store doesnt have it try an electrical supply house. Its a pretty standard item and it shouldn't cost you more than 2 or 3 dollars each. If you found a 12/3 extention cord with nice heavy duty ends on it I'd go ahead and stick with them. Factory ends are always better than ones you could put on. You're right about the labeling. They can't call the cordset 20amps unless it has 20a cord caps on it.

 

[RichBenn]

Unfortunately, I do not have an answer for you - but I am wondering the same thing. I am currently using a 12/3 extension cord like this one for my manual controlled 2000w element. The cord/connectors never even get warm (unlike when I use a cheaper "light duty cord"). Although it is not technically rated for 20A, it seems to have no trouble with my element. I am wondering if the amperage rating is more of a legal issue regarding the type of connector more than a safety issue (to prevent people from overloading cheap cords). As long as you are using heavy duty type connectors instead of the cheapo ones I would think you should be OK. I am in the process of adding a pid and redesigning my system now and it seems to be hard to find information about this.

I'm just trying to be code safe. I'm an EE by training, but residential code has a few things that have baffled me. Most can be traced to actual safety issues; others are "this is the way we've always done it". For example, there are a dozen or more ways I can think of to deal with good ground connections other than twisting the wire together 10 turns plus a wire nut! But try and get one of those past an inspector.

12/3 should be sufficient for 20 amps. It's code for in-wall wiring, at least last time I checked, and the math says it won't get hot.

I did discover something about the "20 AMP" GFCI sockets not having a commercial horizontal blade on the neutral - in some listings, although the socket rating was 15A, the "passthrough" was 20A. This would seem to indicate the whole circuit is 20 amp protected, but one plug is expected to have at most 15A. Or so I surmise.

I suspect you are right about the plugs and sockets - they don't want people plugging in 20 amp devices into 15 amp wiring. But I have at least one saw in the garage that doesn't have a 20 amp commercial plug but will trip a 15 amp circuit under load. Why doesn't it have the horizontal blade if that's a requirement for 20 amp? So is it only a requirement for commercial circuits? I don't have a copy of the NEC (which is what most local codes are based on). Just hoping some electrician or inspector will chime in about these 20 amp plugs and sockets.

I'd probably be OK even on a 15 amp circuit as I'm using 1650 watt instead of 2000 watt heater elements, but I do have a pump and PID to power as well.

 

[RichBenn]

the electrical code allows you to put 15a rated receptacles on a circuit rated for 20a. It allows this because you're not likely to plug one thing in that has that much of a load into one outlet. 20amp rated receptacles shouldn't be too difficult to find. If your hardware store doesnt have it try an electrical supply house. Its a pretty standard item and it shouldn't cost you more than 2 or 3 dollars each. If you found a 12/3 extention cord with nice heavy duty ends on it I'd go ahead and stick with them. Factory ends are always better than ones you could put on. You're right about the labeling. They can't call the cordset 20amps unless it has 20a cord caps on it.

Thanks, I was suspecting this was the case. So another 20 amp GFCI receptacle and I'm good to go. And I finally found some inexpensive 20 amp plugs.

 

[bberr004]

Would you mind letting me know where you found the plugs for cheap (if online)?

 

[grandequeso]

These are such a common item I really don't see it being worth paying shipping on it. Do a search on home depot website for" 20amp duplex". Its onlly $2.99 each or 3 for $30 for a gfci model.

 

[RichBenn]

Would you mind letting me know where you found the plugs for cheap (if online)?

Ebay. Search on 20A plug

 

[RichBenn]

These are such a common item I really don't see it being worth paying shipping on it. Do a search on home depot website for" 20amp duplex". Its onlly $2.99 each or 3 for $30 for a gfci model.

Talking plugs here. $9.99 cheapest HD; About $6 with shipping on ebay.

 

[grandequeso]

you're right, I was looking at receptacles not plugs.

 

[cockybitz]

The situation is that you can safely plug a 15A device into a 20A circuit. You can not, however plug a 20A device into a 15A circuit. If there is only 1 outlet on the circuit, it MUST have a 20A receptacle. Of course, 20A devices are rather rare, so the need for 20A receptacles is also rare. In these times, most residential wiring is 15A to save on costs. The buyer usually knows no difference. Now imagine you had put a 20A receptacle and every time the breaker would trip. Unfortunately, one might simply change the breaker at the service. As you know, this would not be safe as the carrying conductor is only rated for 15A.

 

[bberr004]

Thanks! I am buying 6 of them so this will save be about $20.

 

[grandequeso]

kitchen countertop, bathrooms, and dining room receptacles are all required to be 20a circuits, these are ussually the only 20a 120v receptacles in a house. If you needed two 20a circuits, your kitchen would be a good place to check. Its required that all kitchens no matter how small, have two 20a circuits to feed the countertop receptacles. You just have to figure out which ones were on which circuit as its likely you have more than two countertop outlets, and you don't want to connect both your elements to the same circuit as that would trip the breaker.

 

[thargrav]

When I was a wiring electrician we were required to install two 20A circuits in the kitchen and were only required to install 15A circuits everywhere else. We were also required to install 20A outlets in the kitchen. They looked exactly the same as 15A outlets including the two verticle blades except the outlets and their package was marked 15/20A and they cost a little more. The only place we used the 20A style with verticle / horizontal blades was single use circuits like wall air conditioners.

I suggest you pull one of your kitchen outlets and see what it's rated for. The rating will be molded into the back of the outlet. Also, the 20A outlets with verticle / horizontal blades will accept plugs with two verticle blades.

I'm just trying to be code safe. I'm an EE by training, but residential code has a few things that have baffled me. Most can be traced to actual safety issues; others are "this is the way we've always done it". For example, there are a dozen or more ways I can think of to deal with good ground connections other than twisting the wire together 10 turns plus a wire nut! But try and get one of those past an inspector.

12/3 should be sufficient for 20 amps. It's code for in-wall wiring, at least last time I checked, and the math says it won't get hot.

I did discover something about the "20 AMP" GFCI sockets not having a commercial horizontal blade on the neutral - in some listings, although the socket rating was 15A, the "passthrough" was 20A. This would seem to indicate the whole circuit is 20 amp protected, but one plug is expected to have at most 15A. Or so I surmise.

I suspect you are right about the plugs and sockets - they don't want people plugging in 20 amp devices into 15 amp wiring. But I have at least one saw in the garage that doesn't have a 20 amp commercial plug but will trip a 15 amp circuit under load. Why doesn't it have the horizontal blade if that's a requirement for 20 amp? So is it only a requirement for commercial circuits? I don't have a copy of the NEC (which is what most local codes are based on). Just hoping some electrician or inspector will chime in about these 20 amp plugs and sockets.

I'd probably be OK even on a 15 amp circuit as I'm using 1650 watt instead of 2000 watt heater elements, but I do have a pump and PID to power as well.

 

[grandequeso]

I've seen older gfci recepts that I was replacing be labeled 20a with just the standard configuration. All the newer stuff I've come across that is labeled 20a has the vertical/ horizontal neutral prong. Attatched is the page out of the electrical code that explains how you can put 15a devices on 20a circuits.

 

[RichBenn]

I've seen older gfci recepts that I was replacing be labeled 20a with just the standard configuration. All the newer stuff I've come across that is labeled 20a has the vertical/ horizontal neutral prong. Attatched is the page out of the electrical code that explains how you can put 15a devices on 20a circuits.

I'm fairly sure my kitchen and bath ones had a 20 amp mark on them (at least the two containing the GFCI sockets). Be interesting to see if the others are 15 A ratings.

Pretty certain they adapted a newer version of the NEC code here a few years back; my home was built about 12 years ago under the older code. Probably explains the lack of vertical/horizontal neutral plug.

No matter either way. The new GFCI I'm putting into the second 20A circuit will have the new configuration & I'll use a 520PA plug - thanks everyone for the help!

 

[cockybitz]

I suggest you pull one of your kitchen outlets and see what it's rated for. The rating will be molded into the back of the outlet. Also, the 20A outlets with verticle / horizontal blades will accept plugs with two verticle blades.

Don't bother. If it were rated for 20A it would have the horizontal prong acceptor. Anything that doesn't, is only going to be rated for 15A (If it were rated for more it would have the horizontal). Internally they are not a sturdier build. The internals are the same, but it just has a different facing.

 

[RichBenn]

Don't bother. If it were rated for 20A it would have the horizontal prong acceptor. Anything that doesn't, is only going to be rated for 15A (If it were rated for more it would have the horizontal). Internally they are not a sturdier build. The internals are the same, but it just has a different facing.

Ah, if you read my previous post, you'll see the 20 amp GFCI does NOT have the horizontal neutral, yet it says 20 amps on the socket.

 

[cockybitz]

I apologize. When you said it had a 20A mark, I though you were speaking of the circuit breaker.

 

[RichBenn]

I apologize. When you said it had a 20A mark, I though you were speaking of the circuit breaker.

NP. Kinda why we were bantering this about. Since this thread I've checked some electrician forums where many verteran electricians were also not totally up on the code subtleties of 15 and 20 amp plugs and sockets used on 20 amp service. So I'm not at all embarassed about my own ignorance in this area.

It's not like I was worried I' was going to build something that's going to shock me or start a fire. However, as I'm one to advise others to follow code as a way to be safe, I figure my own build should too!