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Understanding NEMA 5-15 / 5-20 Outlets #214775 01/23/15 09:22 AM
Joined: Aug 2008
Posts: 58
A
andey Offline OP
Member
Hello guys,

I need a quick help in understanding from you as I'm in the process of assembling a machine for use in the US.

NEMA 5-15 Outlet with 15Amp breaker - OK.
NEMA 5-20 Outlet with 20Amp breaker accepts both 15Amp and 20Amp plugs.
If now a 5-15 extension cord with multiple outlets is inserted into the 5-20 Outlet, can't the cord be overloaded? Because the breaker rating is too high?

Thanks,
Andy

Work Gear for Electricians and the Trades
Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214777 01/23/15 11:05 AM
Joined: Apr 2002
Posts: 7,178
HotLine1 Offline
Member
In theory (and the real world), yes the cord could be overloaded, based on the rating of the cord.

Does this happen? Yes.

Any issues?? Warm/hot cord; deterioration of the cord over time.

The NEC does not address what gets plugged into the 5-15 or 5-20, or any other devices, and for all intensive purposes we stop at the device.



John
Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214778 01/23/15 12:39 PM
Joined: Apr 2013
Posts: 22
S
sedesigner1 Offline
Member
I think we all have stories of what the customer has plugged into outlets after we've left. That's why you're only responsible up to and including the device.
Greg

Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214784 01/24/15 12:18 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
Just figured that out, did you?

Now, take a look at the cords with multiple outlets - cords that are only #16 wire ... even a single 15 amp appliance has that cord overloaded.

Look inside one of those outlet strips with integral 15 amp breakers, and you'll find the internal wire is best described as 'dental floss gauge.'

If household wiring followed the same voltage drop advice as we are given for using extension cords, we'd wire houses in #8.

When reality conflicts with theory ... and everything is working fine ... it's the theory, the basic assumptions, that need to be reconsidered.

Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214815 01/27/15 05:16 PM
Joined: Apr 2013
Posts: 22
S
sedesigner1 Offline
Member
When I mentioned what customers plug in, I had a specific case in mind. Home owner had 3 outlets in a small room and wanted a 4th. Not to worry, they bought a 6', #16 extension cord and stapled it to the wall, and plugged in a floor lamp. Then they wanted a closet light. Not to worry, they bought a 2nd #16 extension cord and plugged it into the first, drilled a hole into the closet and again stapled everything in place. Oops, how to connect the light (pull chain fixture)? They cut the 2nd extension cord and hardwired the fixture, and mounted the fixture directly to an exposed wood beam (who needs a box). They told me "it's only 2 lights so it's not overloaded". I was speechless.

Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214816 01/27/15 05:46 PM
Joined: Apr 2002
Posts: 7,178
HotLine1 Offline
Member
OK, time for a stroll down Memory Lane...
Back in time installation of 'outlets' using zip cord, stapled to baseboards and thru walls was common. Matter of fact, Eagle/Leviton made 'devices' for 'surface wiring'.

The device was wired; forget polarity & that 'ground', Screwed to the baseboard, and extended where 'outlets' were wanted. Some installs were 'tapped' off of a duplex, not plugged in.

Light fixtures were installed like Sedesigner1 describes.

Those were the days!! ??


John
Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214817 01/27/15 06:41 PM
Joined: Jul 2004
Posts: 9,485
G
gfretwell Offline
Member
This was the closet light in my daughter's new house when I first saw it. The "home inspector" either missed it or thought it was fine. No switch, you just plugged the cord to an extension cord through the wall from the other room, hanging by the door.
(yeah I fixed it)

[Linked Image from gfretwell.com]


Greg Fretwell
Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214836 01/29/15 05:04 PM
Joined: Apr 2013
Posts: 22
S
sedesigner1 Offline
Member
Nice! I especially like the cable support and service loop. Is that a water pipe at lower right? Even better!

Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214837 01/29/15 05:10 PM
Joined: Jul 2004
Posts: 9,485
G
gfretwell Offline
Member
Oh yeah, That goes to the water heater

[Linked Image from gfretwell.com]


Greg Fretwell
Re: Understanding NEMA 5-15 / 5-20 Outlets [Re: andey] #214838 01/29/15 06:37 PM
Joined: Apr 2002
Posts: 7,178
HotLine1 Offline
Member
I guess you can plug in a water heater?



John
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