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Leviton 3 plug outlets

2008-09-09 15:02:14.092143+00 by Dan Lyke 11 comments

I've seen a whole bunch of links to this Leviton 3 plugs in the space of a normal 2 plug outlet, so here are some curmudgeonly harrumphs about why I won't be installing these in my house.

  • The reason I need more plugs in an outlet is wall warts. This does nothing to make more room for wall warts.
  • Although the only place that this is actively done is hospitals, the right way to mount 3 prong sockets is with the ground pin up, so that dropped objects that might short will fall one way or the other, and short to ground, not across hot and neutral. This is impossible to do with this plug.
  • It claims to be a 20A socket, but it also says:
    AC Horsepower Ratings
    At Rated Voltage:1 HP
    which seems contradictory.

Needless to say, my objections are technical enough that I expect to see these things take over the new and refurbished home market like bad ideas in a Congressional hearing.

[ related topics: Invention and Design Space & Astronomy Economics Real Estate Furniture ]

comments in ascending chronological order (reverse):

#Comment Re: made: 2008-09-09 15:36:37.05346+00 by: other_todd

Wall warts: I prefer to plug these into a horizontal power strip because their weight often tends to pull them partially out of outlets (see next item)

Ground prong on top: You're going to have to be the lone-nut on that one. If I go into a private home and I see a three-prong upside down I think someone was sloppy. (And if your plugs are partially pulled out of the sockets so something could short on them, you have other problems unrelated to wiring.)

Horsepower: That does seem odd. My reference says electrical horsepower is 746 watts, period, the end, and 746/120 = about six-ish amps. Either this is just plain wrong, or they're assuming there are a lot of other draws on the 20 amp circuit at the same time and thus you cannot reliably expect to get MORE than 1 HP in normal use. Dunno.

#Comment Re: made: 2008-09-09 17:02:59.667914+00 by: Larry Burton

Yeah, one horsepower is equal to 746 watts but a one horsepower motor will usually pull closer to 10 amps than the 6.8 amps that calculates out to. You also have an inrush current on start up that needs to be considered so I wouldn't want to power any larger motor on a receptacle rated at 20 amps than a 1 hp.

#Comment Re: made: 2008-09-09 17:20:15.369592+00 by: TheSHAD0W

I'd rather have a short between hot and neutral than hot and ground; neutral *is* ground, and is typically connected via a heavier wire. It's possible for the safety ground to be undersized and a short to neutral is more likely to trip the breaker more quickly.

Having the ground on the bottom also means a klutz is less likely to get a finger on the hot wire while pulling out a plug.

#Comment Re: made: 2008-09-09 22:04:45.908576+00 by: Dan Lyke

I live in a world of GFI, and a hot to ground trip will happen a lot faster than a hot to neutral.

#Comment Re: made: 2008-09-09 22:41:58.904607+00 by: Dan Lyke

Todd, I'm not exactly a lone nut, quite a few references, including the well regarded Rex Cauldwell, agree with me. Of course it does make it more difficult to use some devices which are set up for ground pin down, like the timer we use to run our alarm light. Sigh.

On horsepower, I have a number of handheld power tools that pull a full 15A, I'm sure they're more than 1HP. In fact, when plugged in to the dust collector that should easily be a full 20A. They're generally soft-start, so I could believe that they could be pulling that much running, not just at startup. I also know that it's standard practice to let circuit breakers compensate for starting current.

#Comment Re: made: 2008-09-09 23:06:40.698468+00 by: Larry Burton

I also know that it's standard practice to let circuit breakers compensate for starting current.

The ratings for the two are for different reasons. Receptacles rely on spring clips to maintain a tight connection. Fast heat up and cool downs from high inrush currents can lead to premature failure of the receptacle.

#Comment Re: made: 2008-09-09 23:32:02.753798+00 by: Dan Lyke

Ah. Makes a lot of sense. Which leads me back to reasons I won't be using these receptacles...

#Comment Re: made: 2008-09-09 23:59:27.025797+00 by: andylyke [edit history]

1 hp (out) =746 W out

if motor is 75% efficient, this means ~ 1kW in

if power factor is 80% this means ~1.2kW ~>10A on 120 V, but starting current, stall current, other factors lead to hp ratings considerably below VA/746.

#Comment Re: ground prong on top made: 2008-09-10 09:57:15.406506+00 by: John Anderson

I was quite amused to note that the building I work in for $NEW_JOB (a FedGov building built within the past couple years, quite modern, architecturally speaking) the wall outlets in the hallways are ground-prong-on-top mounted.

FWIW, the ground floor is all "public" space (meeting rooms and cafeterias); all the office space on upper floors is raised floor with power, network, and cooling runs underneath.

#Comment Re: made: 2008-09-10 13:00:26.583814+00 by: meuon

Dan, ground pin up/down is a religious argument that I am in the ground pin up camp, or at least, back when I worked in hospitals I was. Having grounds on every outlet is an arcane practice, but useful when dealing with devices with metal cases, and it can add to the holding cords to the wall connection.

The amperage rating on outlets has a lot to do with the tension and quality of the contacts, a well as the heat load capacity of the surrounding shell and how wires are connected. Personally, I buy a lot of 15+ amp 110 outlets more because I like the firm grip than anything else.

As for grounds.. Larry Burton and I are of the few people that have worked on truly grounded systems. Most are simply tied back to neutral. In older houses, often at the outlet 'cause they only have two wires.

#Comment Re: made: 2008-09-10 19:00:25.119452+00 by: Mark A. Hershberger


Just get real power plugs that make it impossible to touch a ground to neutral or hot.

(/me returns to Rwanda, the only place he has actually seen and used these.)