No announcement yet.

Any Electricians, plug/receptacle question

  • Filter
  • Time
  • Show
Clear All
new posts

  • Any Electricians, plug/receptacle question

    I have two, independent outdoor electrical circuits each with 20 amp/12 gauge rated outlets (sideways or "T" on the neutral side). They on separate breakers and each has an active GFI in their wiring. I am wiring up cords (industial 12 gauge extension 50 ft.) to temporarily provide power to two separate locations. Rummaging through my electrical box of goodies (my stepfather sold electrical distribution equipment so I'm rather well stocked) I came across two, nearly identical male/right angle plugs I'd prefer to use. They are identical in every way EXCEPT one is rated at 20 amps (has the sideways neutral) and the other is like your standard plug with parallel blades and is only rated at 15 amps.

    Now, here is what baffles me (and the reason for my question):

    1. The measured thickness of the blades are identical.
    2. The internal fastening (for the wire) is identical.
    3. The external case is identical.
    4. I even weighed them and they weigh identical.
    5. I broke open a spare 20 amp outlet and inserted the plugs to see if the sideways "T" had any different (greater) contact area. I could see no difference regardless of whether the 15 or 20 amp plug was inserted. They contacted somewhat differently, but the total area of contact was similar.

    Thus, I'm incline to think that the actual amperage capacity is the same regardless of the rating. And I'm thinking the only reason one is rated higher than the other is because on a device that would use greater than 15 amps the sideways "T" plug forces the issue of making sure it plugs into a 20 amp, 12 gauge wire outlet. Hence the difference in rating seems to be based on what the plug may be attached to, and not that the 15 amp rated plug can't in itself handle 20 amps.

    In my case that 20 amp, 12 gauge circuit is already provided. So, it seems acceptable to use the 15 amp rated plug (that has all the attributes of the 20 amp plug) as long as it is plugged into a 20 amp outlet. And for the record, nothing will draw over 12.5 amps on these circuits - this time. In the future it may draw closer to the 20 amps (and why I ask). Comments?
    Last edited by wittsend; 04-20-2016, 08:52 PM.
    '64 Lark Type, powered by '85 Corvette L-98 (carburetor), 700R4, - CASO to the Max.

  • #2
    Should be OK. All the 220 individual plugs(not cable assembly) that I have run across have all the different neutral configurations for 30-40-50 sockets in the box. Same plug, just up to the person wiring the plug to know what size wire(copper)to use, 30amp=10ga - 40amp=8ga - 50amp=6ga. If the plugs are the same specs I wouldn't worry about it, just be sure and wire with 12ga copper wire, anything over 50 ft go with 10ga especially if subjected to a heavy load. I am not an electrician but have done a few whole house rewires with breaker boxes under a homeowners permit and they passed the city electrical inspections. First one in the mid 70's and as far as I know it is still in place, drove by the house a few years ago and it is still there..


    • #3
      I wired and plumbed my house and shop back in the 1980s, and I can tell you that with both the plumbing and electrical codes, common sense does not apply at all.

      When I installed my garage doors, I spoke with an experienced guy who works on the openers. He said that, at least in some brands, the whole range of different models use the same circuit board, which has all the features of the most expensive, unit, but the cheaper units just don't use all the features. Also, the 1/4, 1/3 and 1/2 horsepower rated units all used the same motor, same part number. The only difference was the price.

      I ran a 10/2 direct burial wire out to my gate, total length about 700 feet. It may be important that I ran a continuous uncut wire from the power panel to the gate opener. The engineering reference charts show that is much too far for a number 10 circuit. I hooked up a 2 1/4 hp skill saw, made a heavy cut on some wood with it and the voltage dropped from 117 to 95 volts. My gate opener is made using a standard 1/2 hp rated garage door unit, has worked perfectly since 1993. I am confident the electrical inspector would never approve this install. They would tell me to use a junction box, then run the cheesy Romex type wire through the walls of my building, because the much tougher and higher quality direct burial wire is "not rated for above ground use" and cannot be used inside the perimeter of a building.
      Trying to build a 48 Studebaker for the 21st century.
      See more of my projects at


      • #4
        You are exactly right on the reason the plug and outlets are made that way. Just keep in mind the codes are for safety and if you don't understand them, they don't make common sense. Someone could come behind a wiring situation and get confused on the use of a improperly rated plug.