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NateDiggity's avatar
NateDiggity
Explorer
Jun 28, 2017

Really dumb extension cord Q

I believe I know the answer but want to get some clarification...

If I am to use an appropriate size 15/20 amp extension cord (10 gauge) for shore power but am adapting either end up to the 3 prong 30 amp, is this considered a 30 amp service still? Or is it necked down to 15? AC electricity is not my strong suit, which drives me nuts because I am great with DC.... but in my DC mind the 10/3 wire is the same as an normal RV extension cord, just wondering if I have an 15/20 amp household style plug on either end, am I "necking it down"

?

Reason I ask is I have a 25' 10/3 ext cord now that I never use around the house, but would like to pack it with me and use my adapters I already have rather than spend $50-$60 on a "RV ext cord"
  • BB_TX's avatar
    BB_TX
    Nomad
    Jun 28, 2017
    The extension cord should be of a size to handle the circuit breaker rating.
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Jun 28, 2017
    No, you are apparently plugging in to a 30 amp RV receptacle, but you are delivering only15/20. What protection, as in surge protection, are you using?
  • Dutch_12078's avatar
    Dutch_12078
    Explorer II
    Jun 28, 2017
    The lowest amp rating part of the cord will determine it's maximum current rating. If you have a 15/20 amp plug on one end, then it's a 15/20 amp rated cord. It's the old "weakest link" maxim...
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jun 28, 2017
    NateDiggity wrote:
    is this considered a 30 amp service still? Or is it necked down to 15? "


    15, The smallest rating is the "Shore" outlet you are plugging into and that limits you to 15. So it is 15.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jun 28, 2017
    Dutch_12078 wrote:
    The lowest amp rating part of the cord will determine it's maximum current rating. If you have a 15/20 amp plug on one end, then it's a 15/20 amp rated cord. It's the old "weakest link" maxim...


    Exactly..

    30A RV plugged into a 15A outlet via extension cord and adapter is limited to the 15A

    Enough amp/watts for power to converter for charging battery, running a microwave or a 13.5K A/C (one at time) and fridge/water heater on electric (one at time).....and ALL DC equipment
  • naturist's avatar
    naturist
    Nomad
    Jun 28, 2017
    Dutch_12078 wrote:
    The lowest amp rating part of the cord will determine it's maximum current rating. If you have a 15/20 amp plug on one end, then it's a 15/20 amp rated cord. It's the old "weakest link" maxim...


    Yes, and if the WIRE is the lowest rated part, THAT will determine it's maximum capacity. So if you take a 20 amp extension cord and cut off both ends, then put on 30 amp plugs, you still have only a 20 amp extension cord. If you try to run 30 amps through it, it is going to get hot, maybe even to the extent of catching fire.
  • Dutch_12078's avatar
    Dutch_12078
    Explorer II
    Jun 29, 2017
    naturist wrote:
    Dutch_12078 wrote:
    The lowest amp rating part of the cord will determine it's maximum current rating. If you have a 15/20 amp plug on one end, then it's a 15/20 amp rated cord. It's the old "weakest link" maxim...


    Yes, and if the WIRE is the lowest rated part, THAT will determine it's maximum capacity. So if you take a 20 amp extension cord and cut off both ends, then put on 30 amp plugs, you still have only a 20 amp extension cord. If you try to run 30 amps through it, it is going to get hot, maybe even to the extent of catching fire.

    Absolutely! In the OP's case though, the 10ga wire size is correct for 30 amps, but the 15/20 amp plug isn't.
  • DrewE's avatar
    DrewE
    Explorer II
    Jun 29, 2017
    While the other posters are correct about the ratings of the cord and connectors (at least the official and guaranteed ratings), it's worth noting that the circuit breaker protecting the circuit will still be a 30A breaker and so you run the risk of overloading the connectors without it tripping. It would be wise to keep tabs on the electrical usage to prevent an overload.

    As a practical matter, if the connectors are not getting at all warm, you're being safe regardless of their putative ratings...but you will not find me posting any suggestion to exceed the official ratings here.
  • jyrostng's avatar
    jyrostng
    Explorer
    Jun 29, 2017
    I think This part or your question is confusing ( If I am to use an appropriate size 15/20 amp extension cord (10 gauge) for shore power )? A 15/20 amp cord is not 10 gauge, a 10 gauge cord is usually 30 amp unless it has 15 amp ends on it. If it does, take the ends off and put regular rv plug ends on it and it will be a 30 amp cord. Then if you plug into a 30 amp rv type plug, you will have 30 amp service. Like others said, the lowest amp device is what it's de-rated to.
  • ken56's avatar
    ken56
    Explorer
    Jun 29, 2017
    Keep in mind voltage drop. How many feet away is the plug and how long in total are the cords? Get a voltage meter that plugs into an outlet (Camping world, about 15 bucks) in the trailer and be sure you are getting sufficient voltage to your trailer. Low voltage will wreck an air conditioner pretty quickly.

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