Extension cord gauge requirements

[Tad Zelski]

I have a 16 ft Bambi Sport with 30 amp system. What gauge extension cord will I need to run 100 feet from the outlet?

[Mollysdad]

Originally Posted by Tad Zelski

I have a 16 ft Bambi Sport with 30 amp system. What gauge extension cord will I need to run 100 feet from the outlet?

I found this chart, and it recommended 6 ga. for a 100' run at 30 amp 120v.
However, I've never seen a 100' 6ga. extension cord, even welder cords are limited to 50'. Is there an alternative plan? Move the outlet closer?

[BayouBiker]

Online, including Ebay, I find a lot of 100 ft 30A 10 gauge AWG cords, I don't find many 6 gauge and they are pricey. The 10 AWG will have 6 Volts loss while the 6 AWG will have 2.4, both are acceptable though 6 V loss is getting up there.

Working in your favor is that you won't often be drawing more that 20 Amps with a modest 4 V for the 10 AWG. The AC draws about 12 the water heater about 8 converter 0.5-3, refrig 2-3 everything else not much.

Clearly 6 gauge is better than 10 but 10 will work. they are still $200 for the cheapest I saw.

[Tad Zelski]

thanks for the advice. I have moved closer to the outlet and now at 50' and have a 10 gauge copper extension cord.

[rowiebowie]

Originally Posted by Tad Zelski

thanks for the advice. I have moved closer to the outlet and now at 50' and have a 10 gauge copper extension cord.

You should be fine. I use a 10 ga. 50 ft. cord at home from a 20A outlet with no problem running the A/C at about 11-12 amps. I see only about a 3-4 volt drop when the A/C is running. Cord, plug, and outlets remain cool

Because it is only a 20A outlet, I never run anything significant at the same time as the A/C.

[Bill M.]

Should work. If you use it a lot you need to sorta keep a check on your connectors and adaptors. I leave my trailer plugged in and due to rain, dirt, and maybe other factors have had to replace several burned up connections. One time it fried the connector on the end of the Airstream cable too, And a little AC voltmeter plugged into the trailer will tell you if you have too much voltage drop under load,

[DaveG]

Your main concern is voltage drop. The greater your electrical load and the greater your cable length the more drop you will experience. The larger the wire gauge the more current your cable can handle but also the more it will weigh and be difficult for you to handle. Demand factor is part of the equation. A 30 amp service does not mean you will use 30 amps all at the same time. A motor load like your AC will suffer the most with voltage drop. The motor will overheat on low voltage. In almost all cases a #10 gauge cable of 50' length will be satisfactory if your source is good. Voltage will vary from site to site and in some cases vary depending on the quality of the site installation. Voltage fluctuations may occur based on your neighbors demand if the site installation is weak. A digital voltmeter is a good tool to carry. Lots of talk about this subject in existing threads. Hope this helps.

[switz]

Note that most of the “RV” power cords use just #10 wire which is rated for 30 amps. It is possible to get 50’ 30 amp cords. There is never the necessary tidbit of information about voltage drop and burning up the compressor in the air conditioner if ANYTHING else with a large current draw is running...

It is possible to buy 100’ #6 wire 50 amp 240Vac RV power cords. They weigh a lot and are a chore to handle. A properly wired 50 amp trailer will have an air conditioner on each leg of the 240Vac power supply, so the voltage drop is not a concern with just air conditioners running.

[gklott]

Recommend ensuring the extension cord you use is UL-listed for this purpose. Also, recommend being careful with any extension cord with longer term environmental exposure. Direct sun exposure and resulting heat can quickly degrade some cheaper cords.

[bibbs]

To be on the safe side keep the water heater on propane, another concern is how far is the house outlet from the main panel box. You can buy #6 cord with 3 conductors for 120v then put RV ends on it , that would be 25% lighter.

[Silvr_Bullet]

Originally Posted by Tad Zelski

I have a 16 ft Bambi Sport with 30 amp system. What gauge extension cord will I need to run 100 feet from the outlet?

Tad, I wouldn’t run the air conditioner or Heat Strip with an extension from a 110 outlet.

[Doc Foster]

I successfully use a 100 foot 10 gauge extension cord to power my trailer when "stored" at home. I can run ONE of the A/C units OR the microwave OR the electric hot water heater, but none of them at the same time. I have run ONE of the A/C units for several hours in the heat of the summer when working on the trailer interior, cleaning, prepping for a trip etc., but not for extended periods of time, probably no longer than 6 hours. I did feel the extension cord a few times and it was warm, but it was bright and sunny so not sure if it was warm from use or from the sun? I have done this for several years and the A/C units are still functioning normally. I keep it plugged in frequently for 6+ months to test all of the systems before leaving for a trip and to keep the fridge on (and nice and cold) and to keep the batteries charged, so it is always ready for use. Also just in case one of us has to self quarantine we can use the trailer for a couple weeks. It is plugged into a 20 amp, 110 volt dedicated circuit in my garage. Trailer is about 80 feet from my house (due to a steep driveway).

[Silvr_Bullet]

Originally Posted by Doc Foster

I successfully use a 100 foot 10 gauge extension cord to power my trailer when "stored" at home. I can run ONE of the A/C units OR the microwave OR the electric hot water heater, but none of them at the same time. I have run ONE of the A/C units for several hours in the heat of the summer when working on the trailer interior, cleaning, prepping for a trip etc., but not for extended periods of time, probably no longer than 6 hours. I did feel the extension cord a few times and it was warm, but it was bright and sunny so not sure if it was warm from use or from the sun? I have done this for several years and the A/C units are still functioning normally. I keep it plugged in frequently for 6+ months to test all of the systems before leaving for a trip and to keep the fridge on (and nice and cold) and to keep the batteries charged, so it is always ready for use. Also just in case one of us has to self quarantine we can use the trailer for a couple weeks. It is plugged into a 20 amp, 110 volt dedicated circuit in my garage. Trailer is about 80 feet from my house (due to a steep driveway).

I use that setup basically the same except for the air conditioner or in my case the heat strip. I use a 1200 watt electric heater in the winter one year I ran it for the whole winter so it toggled between 800 - 1200 watts but I had house battery removed so no in house charger. It would be nice I need to check with my electrician for air conditioning needs.

[Beewee]

I bought four 25 foot 10 gauge extension cords from Milspec Industries. They lose very little voltage at the connections, so I always have enough length, but not too much length, for any situation. They come in 5 colors and they even printed my last name on all the cords to discourage theft. All four cost $156 on-line four years ago. We used them at my sister-in-laws rural house when plugged into their house, while camped in their yard for a week. We use one of them when "prepping" for travel next to our home for a few days.

Make sure the AS batteries are completely charged, and the water heater is NOT on electric, before running ONE A/C unit (we have two). Did not run the Microwave while the A/C was on (during the mid-day time only). This worked great for us.

Link to their product:

https://www.milspecind.com/heavy-dut...4&240_ss=12811

Good luck.

[KevinFH]

Originally Posted by Silvr_Bullet

Tad, I wouldn’t run the air conditioner or Heat Strip with an extension from a 110 outlet.

There is no reason not to do run the air conditioner. Sure, it's "better" to have full rated voltage, but the voltage drop on a 10 gage 50 ft cable is insignificant.

You can measure the voltage at the CB panel. Then compare the voltage measured to the voltage range the airconditioner is rated for. 10V low would not be a big deal for most loads on the AC voltage circuit.

On the forums, there are a lot of "rules of thumb". These are quite helpful when you don't know the exact details or arithmetic to make an engineering decision. But, rules of thumb are usually very conservative.

I have found it is much more important to use dielectric grease on my 7-pin connector that it is to operate the AC from a 30A breaker. The AC does not use 30A, closer to 10 amps is correct. A 20A source is fine.

[Silvr_Bullet]

Originally Posted by KevinFH

There is no reason not to do run the air conditioner. Sure, it's "better" to have full rated voltage, but the voltage drop on a 10 gage 50 ft cable is insignificant.



You can measure the voltage at the CB panel. Then compare the voltage measured to the voltage range the airconditioner is rated for. 10V low would not be a big deal for most loads on the AC voltage circuit.



On the forums, there are a lot of "rules of thumb". These are quite helpful when you don't know the exact details or arithmetic to make an engineering decision. But, rules of thumb are usually very conservative.



I have found it is much more important to use dielectric grease on my 7-pin connector that it is to operate the AC from a 30A breaker. The AC does not use 30A, closer to 10 amps is correct. A 20A source is fine.

Thanks for that, I have been led to believe that start up is the problem in that it will take 2-3 x more wattage to start and therein lies the problem.

[OTRA15]

Do it right, or don't do it at all!

Buy 100' #6 wire of your choosing, and put the correct ends on it. In the overall long-term scheme of things, investing in the right tool for the job pays for itself over time IMO. What is your total investment in the tow vehicle and trailer? What percentage would an up-charge be, for the right setup?

Get the heavy-duty wire that is designed for wet locations and laying directly on the ground, like they use for setting up music festivals etc..

Benefits>>>>>cost.

KISS

Peter

PS -- If you don't want to play at this level, sell the Airstream and get a tent IMO.



PS2 -- Or direct burial as suggested.

[Mollysdad]

Originally Posted by switz

It is possible to buy 100’ #6 wire 50 amp 240Vac RV power cords. They weigh a lot and are a chore to handle.

At that point it's practical to just use three single cables with cam locks. And much easier to store.
Massive overkill for 30 amp RV. The OP was right in moving closer or have an electrician install direct burial cable to a new pedestal.

[KevinFH]

Originally Posted by Silvr_Bullet

Thanks for that, I have been led to believe that start up is the problem in that it will take 2-3 x more wattage to start and therein lies the problem.

Start up surge is much more, but usually, it doesn't hang around long enough to trip a thermal circuit breaker.

[switz]

Note that folks are talking 12 to 15 amps for the 15K air conditioner. That number is the running amp draw, not the startup which can be many more times the running amps. The high start up power draw is when the voltage drops and the compressor motor can over heat the motor's insulation or damage the capacitors. The Easy Start's concept includes shortening the time for the motor to start to reduce exposure to damaging low voltage from insufficient wiring.