Stringing together multiple extension cords

Discussion in 'Electrical Forum discussion & Blog' started by teve, Sep 24, 2011.

  1. teve

    teve New Member

    Messages:
    57
    Location:
    Minnesota
    Are there any electrical issues with stringing together multiple outdoor extension cords, (for a 12 Amp leaf blower), as long as they are all at least 12 Amp cords?
  2. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    Multiple short ones are the same a single long one, but unless you get ridiculous on the number of ones connected together and their connections are ALL tight, there is no prohibition.
  3. LLigetfa

    LLigetfa DIYer, not in the trades

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    Location:
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    If they are the cheap injection molded ends, expect them to be high resistance and heat up. Most every extension cord I have has had at least the female end replaced with a higher quality end.
  4. cacher_chick

    cacher_chick Test, Don't Guess!

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    How much is too much depends on the quality of the cords and their connections.
    If the voltage drop from the length of the cord becomes too great it will damage the motor. If the connections are not very good, the plugs will overheat and burn.
    How much is too much depends on the quality of the cords and their connections.

    If this is something you will be using on a regular basis, it would be much better to have a branch circuit with outlets installed out on the property so you don't have to use great lengths of cord.
  5. teve

    teve New Member

    Messages:
    57
    Location:
    Minnesota
    Thanks for the replies. (One more question below.)

    I have 50' and 80' 15 amp cords (and another 50' 13 amp cord I probably would not need to use), mainly for a 12 amp leaf blower/vac on a smaller size yard with one tree. I want to cover the front and back yard using one outlet. It sounds like I should have no problem. It seems I just need to make sure the plugs don't get warm and I assume 180' with three cords is far from being ridiculous.

    My leaf blower has variable speed which I am guessing is controlled by the voltage applied to the motor. If there were a significant voltage drop due to excessive length or high resistance connections would that still be an issue for the motor?
  6. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
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    Location:
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    IMO, trying to do anything with 180 feet of extension cord is ridiculous.

    Save yourself a lot of trouble and get a gas powered blower.
  7. teve

    teve New Member

    Messages:
    57
    Location:
    Minnesota
    I would very likely not ever use 180 feet for anything. It was more of a hypothetical comment and question. I'll probably just stick to using the 80' cord only. For my size lawn and only one tree, and a couple bushes at the edge of the yard, the electric blower seems to work out very well.
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Last edited by a moderator: Sep 26, 2011
  9. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    Seems to me if its a brush motor, and likely is, more cords will just give him a hair dryer.

    I have had many an argument with electricians wiring to submersible pump motors made by Franklin. Franklin actually designs its motors to start on reduced voltage and encourages it because it reduces stress on the impeller shaft. Mimics a soft start unit of great expense.

    Take a look at Franklins wiring chart and how economical it is vs. the NEC. Point being: the link wire chart does not apply to certain motors and installations.

    http://www.franklin-electric.com/aim-manual/page-11.aspx
    Last edited: Sep 25, 2011
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

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    The point being; if it doesn't meet the NEC then it won't pass inspection no matter what Franklin publishes
  11. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    That means about 10 million wells in the USA need the wire changed. Ask any well driller. And Inspectors dont get involved with whats going down a well 99.99% of the time.

    The manufacturer deems the installation safe for the specialized motor and its a rare inspector that does not defer to the Mfgr's specs.

    Maybe the NEC bible needs an update for well motors. Save the poor consumers billions in useless copper.
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    Here in good old North Carolina a well driller cannot install the wires to the pump unless he holds an electrical license. The electrical inspector will always look at the conductors that exit the well cap for the size of the conductor.

    Any manufacture can mandate conductors larger than that called for by the NEC but no manufacturer can ask for anything to be installed smaller than what is mandated by the NEC.

    As one can see the code is a bare minimum safety standard and anything less is not safe.
  13. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    That must be why so many of us moved to California.

    And when you have a dedicated line to a motor designed to SAFELY run on, say 600' of #10 cable and the NEC wants # 6 or 4, you have a serious malfunction between entities. And I bet it means a lot of people neglect to call for a permit. And its a sad waste of a precious commodity that a lot of people cannot afford in our depression.

    Starting a 3" submersible pump motor has no relationship to a split phase basic utility motor. Perhaps the NEC should address that.

    Sort of like the 100 year old barns in the area with 2x4 rafters that now require 2x12's. I know asking you to question authority is a real uphill run, but much of it has run amok.
  14. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    As you pointed out the pump can safely operate on 600 feet of #10 then why would the NEC not allow it?

    Around my area we are talking about 3 to 4 hundred feet from house to pump and in most cases it will be #12.
  15. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    Excellent question for you. I get enough loaded questions from my employees. Ostrich effect? No chapter for dedicated lines to submersible pumps? Not interested in specially wound dedicated purpose motors? Copper lobby bought the NEC boss a golf trip to Bermuda?

    We cannot say that its an issue of the next guy coming in and putting in a split phase motor, or a 3 HP motor, because a man with a 3500 watt wall heater and a NEC approved wire run to it can just as easily come in and install a 5500w or greater replacement heater. In all cases an ELECTRICIAN or preferably for the well, a pump man would re-evaluate the wiring for the new load.

    The smallest paragraph in the NEC bible referring installers to the pump motor MFGRS. specs might save millions of tons of copper a year. Seems a worthy cause.

    Recently caught a guy in the pump forum with the same situation that forgot to add in the 400 feet down the hole. Got a nice thank you from him.
    Last edited: Sep 28, 2011
  16. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    As the electrician installing the conductors I include the distance from the point of overcurrent to the electrical motor that turns the pump. What did you think I was addressing, from the house to the well head?

    If the pump has the minimum circuit ampacity and the maximum overcurrent marked on the name plate this is what gets installed. If the pump is simply marked with its horse power then I go to Table 430.248 and do the math.

    What is left to discuss?
  17. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    If you have a above ground jet pump, then you are correct. If you have a 3" Franklin wound, special purpose motor, you should, out of decency to your clients and the earth, use their carefully designed wire chart.

    As to house to well head, if you have a 3 wire pump, one can use the NEC to get there, and then use the chart for Frankklins 3 wire pumps to go down the well. These may be several sizes smaller. One line is used for starting and running cap.

    Its a whole different ballgame, and I think the NEC deserves to give your students more information.
  18. BobL43

    BobL43 DIY Senior Member

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    and the winner is: nobody. does there have to be a winner with everything?
  19. ballvalve

    ballvalve General Engineering Contractor

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    Location:
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    The loser is the homeowner that gave up a trip to Hawaii in copper cost because of a system that does not fully address reality.
  20. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,531
    Location:
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    I see nothing wrong with this suggestion as long as the carefully designed wire chart does not conflict with the NEC

    From the panel to the motor that turns the pump is a series circuit. In a series circuit the current is the same throughout the circuit.
    So how does the Franklin pump wiring chart account for this? Has Franklin somehow figured out how to divide current in a series circuit?

    No, The laws of current flow does not change due to Franklin pumps.

    Side note
    I received this in an email this morning and posted it here. The above was sent to me by a student and I agree with the student

    Edited to add
    What the students and myself do know is the difference in Tables 310.15(B)(16) and (17) and so on in the NEC (2011) edition.
    Last edited: Oct 1, 2011
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