SPDT double-throw switch

Discussion in 'Electrical Forum discussion & Blog' started by Ken Tannenbaum1, Dec 27, 2010.

  1. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    Odd, yes, sort of.
    Legal and SAFE, also YES!

    Just because you don't understand this stuff fully please don't criticize those of us that do!
  2. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    True, but it specifically refers to the fact that a built-in receptacle can be used in place of one specified in 210.52(B), meaning they don't want the heater shared with a general use receptacle.
    In this case we are talking about a receptacle dedicated to an air conditioner.

    IMO there are a BIG difference here.
  3. Bird Doo Head

    Bird Doo Head New Member

    Messages:
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    Location:
    Detroit
    I suppose your interpretation of the reason the paragraph exists could be valid. But, as we all know, each AHJ has their own take on things. I'd be more inclined to pass a shared circuit if the outlet sharing with the heater was a single receptacle outlet on the yoke and it was blocked by the air conditioner. (Alternatively, a twist lock.) It might fly if the A/C was the indoor unit from a split system (again, placing the receptacle so it can not be used by anything but the A/C). I'd also have to calculate the circuit, consider motor load, etc.

    Yes, the built-in receptacle may always, always be counted as one of the 210.52(A)(1) required receptacle outlets. This paragraph is provided so the "no receptacle outlet above the heater" requirement of the manufacturer does not prevent a residence from having the required 210.52(A)(1) outlets. Picture a room with electric baseboard heaters from end-to-end on one wall. Since you may not install a receptacle above an electric heater, how would you be compliant with "no point along the floor line shall be more than 1.8 meters from ... "? That is why the sentence allowing the built in to count is in the NEC. (Floor receptacles aren't necessarily the answer. One could still drape cords over the heater, going up to a table lamp and they can be very impractical, costly to install & possibly not approved to count as one of the required.)

    I know for an absolute fact any 120 volt receptacle on the heater circuit would not pass in Detroit; commercial or residential. I can also name several other jurisdictions where 424.9 (or is it .10? I forgot) has been firmly judged to mean no receptacle outlets on the heater circuit.

    Electric heaters' receptacle outlets are often the subject of questions because electric baseboard heat is popular around here in older homes with hydronic or steam heat. People add rooms and don't want to (or can't) tap the wet system. Or, like me, have a room that is allowed to freeze and don't want to send the hydronics out there, thus requiring glycol.

    Please don't forget about the possibility of this receptacle outlet being in a room requiring protection by an arc fault device. I suggest you keep it simple and straight forward. I'd separate the heater circuit.

    Since you have to get tools out, drill holes, pull & staple NM, bash your head on joists, put the tools away & clean up the mess anyway, you might as well pull in two circuits. But this is your house and you are the one paying for the cable and doing the work while I'm sitting at home with my feet up, reading a good book and enjoying a deelicious glass of Kool-Aid!

    Thanks for letting me give my thoughts on the matter,
    Paul
  4. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    Location:
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    Well, it is obviously not clear cut so that gives an AHJ quite a bit of leverage if they choose.
    Thankfully the whole country is not Detroit.



    What I or we would do is irrelevant here IMO. The question has become is it legal to have 120v A/C and 240v electric heat load share a common MWBC. IMO yes.

    If you must know. Would I do it? I have to say maybe. Depends on the situation.
    Under "normal" conditions of course not.
  5. ballvalve

    ballvalve General Engineering Contractor

    Messages:
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    Location:
    northfork, california
    Posted by marne rock.....

    I intuitively and historically understand electric circuits so well that I do not hide behind obscure and worthless quotes from the NEC. For you to pursue this obtuse circuit as being "allowed", makes me think you may be imbued with knowledge of the law but inept when it comes to pulling a wire and thinking about how it will interface with actual, daily use.

    I would never subject my customers or self to a "doubled up" circuit breaker, certain to be overloaded by a customers actions at a later date.

    An advocate of correct, failsafe circuits as yourself should have told the original poster that he needed to simply pull a 12-2 wire for the AC and spend and extra 8$ To protect his family and follow the law and adhere to the best practices. I believe Mr.Birddo has given you sufficient information to retract the previous defenses.

    If anyone else bothered to read this forum, you would have many more detractors in what seems to be a private club of dubious distinction.

    Once again in the hopes of getting you to understand, you proposal seems to be the same as saying that your rooftop AC drawing 40 amps, might as well also have 2 more wires on the same breaker feeding a 40 amp electric wall heater, "because they won't be on at the same time"

    Its not going to be accepted by any inspector or electrician with a scant bit of sense.

    And thanks HJ for the switch idea backup, which started this whole thing. I originally said he needed total disconnect of the two circuits, OR 2 seperate wire runs, of which only the seperate breaker and wire run made any practical sense.
    Last edited: Dec 31, 2010
  6. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    What a complete and utter JOKE!! I literally LOL'd when I read this!


    I intuitively and historically understand electric circuits,......So that means you know everything that is safe and legal to install? Or you just know how things work?

    "obscure and worthless quotes from the NEC"......you HAVE to be #@$* kidding me!!
  7. Bird Doo Head

    Bird Doo Head New Member

    Messages:
    19
    Location:
    Detroit
    This Was Fun

    To All Who Took The Time To Post On This Thread,
    This thread was a fun one! Thank you for letting me join in.
    It is nice when people can have differing opinions and enjoy a pleasant back-and-forth!
    (Somehow, the NEC seems to instigate this often.)

    I want to wish all who read this a Happy, Safe and Blessed New Year!

    Paul
  8. ballvalve

    ballvalve General Engineering Contractor

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    northfork, california
    That might be a good ending. But an ad for BASEBOARD HEATERS just popped up here. Now that is humorous!
  9. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
    North Carolina
    Through out the 1980s I wired multifamily dwellings all up and down the Eastern Seaboard. In quite a few of these units I would pull a 20 amp circuit to a single receptacle for an air conditioner and from there to multiple thermostats for baseboard heat. Not only was this passed by the local inspector but also by the Federal HUD inspector as some of these units were low rent projects.
    Now it might that none of us, inspectors both state and federal or contractors have as much intelligence as some lowly well pump installer but we did it anyway. If you think it necessary I will get a dispatch out immediately to these individuals that this issue needs to be addressed but I think that it would be about thirty years too late.

    By the way the Rock of the Marme is the 3d Infantry Division and part of the XVIII Airborne Corps and is directly responsible for you being able to sit and debate your feelings here.
    Do a Google search of Rock of the Marme
  10. ballvalve

    ballvalve General Engineering Contractor

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    Yes it is 30 years too late. They probably rewired the circuits after 200 trips to the circuit breaker. In 1980 we didnt even have a building department here, so I would'nt give it a shot today. And your circuit is different from what is in this thread, its 20a 120v on one leg, not a shared load on 2 wires.

    Dad speared, burnt, and shot his share of our pacific enemies in the big war, island by island, so I won't require any education about the military, especially since he spent the next 15 years as a drill sargeant. Saved you from eating rice and writing left to right and inside out with little squiggly lines. Thanks to the guys in Europe too, but they did'nt have to sleep with 3 foot long centipedes and spiders the size of a 200 amp entry panel.

    http://www.32nd-division.org/history/ww2/32ww2-1.html
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

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    2,565
    Location:
    North Carolina
    Hello and welcome to the discussion. For clarity I will post the two code sections you mentioned.
    Now to help us better understand the NEC let me post one more section of that same Article.
    Don’t know if anyone has ever seen or installed any 120 volt baseboard heaters or not but I have included them on a general branch circuit. It might also be good to know just how figuring the load for a branch circuit takes place.
    Being that no one would be operating their baseboard heat and an air conditioner at the same time one can be omitted in the calculation.

    Nowhere in either 210 or 424 does it forbid the installation of a 120 or 240 volt AC receptacle on the same circuit as baseboard heat. No this is not like wiring a pool pump on the same circuit as a rooftop swamp cooler either as some keep throwing out there.

    Pete or Paul I would love to hear you thoughts on this.
  12. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    No one should be driving their car, talking on a cell, eating fried chicken and a beer at the same time but it happens every day.

    Sounds like you don't have any low ball renters or have not been in some of the low rent tenements. How about granma with early alzheimers? She will run the AC full blast because she cant figure why its so damn hot inthe house [baseboard on all summer].

    Sorry, but circuit breakers, in my extra-ordinarily humble opinion, are not designed to educate the public.

    Dedicated circuits remove the stupidity factor and do not cost much more.
    Last edited: Jan 2, 2011
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Now come on we all know that you have enough electrical knowledge that should the heat and a
    AC be on at the same time it wouldn’t last long. The breaker would limit the time they both were on. Now Grandma in her mental state wouldn’t be resetting the breaker would she.

    As to your analogy of drinking and driving shows …………..well I just won’t go there.
  14. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    Completely and blatantly irrelevant.

    You earlier said things like this are likely. What you are describing are rare and unlikely occurances.
    If this does happen on a rare ocassion the breaker will simply do it's job and trip. No harm, no foul.
  15. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    I suspect if I had proposed the original wiring scheme, you guys would have found a way to make it illegal.

    I suppose we will just have to follow our own mindset and concept of BEST use of circuit breakers.

    One last shot for you guys to jump on: Ever see a thermostat without a HEAT/COOL switch? Seems like your premise would allow me to install a seperate heating and cooling unit and thermostats, then run the 2 sets of wires to one breaker. "Because they probably, maybe, shouldnt be on at the same time" - hey, the breaker will fix the mistake!
  16. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
    North Carolina
    Something that I just can’t understand about this discussion and what you are saying BallValve.

    We have on several different occasions made the comment that a receptacle for a window AC unit and a baseboard heater can be on the same circuit but you insist on inserting several different appliances and wiring methods into the discussion.

    Why is this??????
  17. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    I would call it extrapolation. But the failure to communicate would be the better and hopefully final answer.
  18. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

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    1,001
    Location:
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    Here. I fixed it for you:
  19. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    Thanks, that settles it. Now get out there and wire up some silly circuits.
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