My trailer came with, what I believe to be, a 25-foot 30-amp power cord that connects to trailer with a round connector with locking ring... fairly standard for trailers from what I've seen. My question comes to the use of an extension cord with this cable. I've looked at extension cords that are 50-feet long, as there is a camping space where I know it will be around 75-feet or so away from the nearest I can park my trailer. I've looked up charts listing appropriate gauge wire for different length runs at single-leg standard voltage. For up to 50-feet, it recommends 10-gauge wire. For 75-feet, it recommends 8-gauge wire. For 100-feet, it recommends 6-gauge. My assumption is that the power cord for the trailer is 10-gauge. 50-foot RV extension cables are also 10-gauge. This jives with the chart I looked up... BUT... I'm plugging 25-feet into 50-feet, a total of 75-feet. At 75-feet, the recommendation is 8-gauge. I have not seen an 8-gauge, 50-foot extension, nor would it take into consideration the 25-feet of 10-gauge for the main trailer. Am I just over-thinking this? Is it an issue?

10 gauge should be fine, I run 60' of it running air con and it's fine. From what I see on Amazon, if you want to go 8 or 6 gauge, you'd need a 50a extension.

"My assumption is that the power cord for the trailer is 10-gauge. 50-foot RV extension cables are also 10-gauge. This jives with the chart I looked up... BUT"STOP assuming. Instead, LOOK at the cable. The wire gauge is printed on the cable insulation. (at least it was when it was new) There's your answer. If the printing/embossing is no longer visible, pull the cover off the j-box where the cable connects just inside the RV. Look at the wire. "Am I just over-thinking this?"No. IMO, You aren't thinking at all. You are reacting.Chum lee

10 AWG is fine for 75 line feet. Yes you will have some voltage drop. It should be within operating specs of most of your gear. Www.calculator.net has a voltage drop calculator based on wire gage, wire length and amperage use. It's pretty accurate. No AC & microwave at the same time! 120vac pulling 30 amps through 75' of 10AWG drops voltage to 115.4vac IIRC from the other page.

Boomerweps wrote:No AC & microwave at the same time!x2, and no water heater. Even at 30' I'll melt plugs doing that.If I need a/c and MW, like for dinner on a hot day, I'll use my inverter! Yep.

Yes, it can be an issue. If you need the full length, then limit the load to less amperage so that there is less voltage drop. Sometimes you might be in a campground where the voltage is already low and you can't afford any loss. Get a voltmeter that displays all the time so that you can see at a glance what is going on. Running a motor driven appliance like the A/C can result in damage if the voltage is too low.

Gauge of extension cord | Good Sam Community

Lynnmor
Explorer
May 17, 2019
Yes, it can be an issue. If you need the full length, then limit the load to less amperage so that there is less voltage drop. Sometimes you might be in a campground where the voltage is already low and you can't afford any loss. Get a voltmeter that displays all the time so that you can see at a glance what is going on. Running a motor driven appliance like the A/C can result in damage if the voltage is too low.
2oldman
Explorer II
May 17, 2019
Boomerweps wrote:
No AC & microwave at the same time!
x2, and no water heater. Even at 30' I'll melt plugs doing that.

If I need a/c and MW, like for dinner on a hot day, I'll use my inverter! Yep.
Boomerweps
Explorer
May 17, 2019
10 AWG is fine for 75 line feet. Yes you will have some voltage drop. It should be within operating specs of most of your gear. Www.calculator.net has a voltage drop calculator based on wire gage, wire length and amperage use. It's pretty accurate. No AC & microwave at the same time! 120vac pulling 30 amps through 75' of 10AWG drops voltage to 115.4vac IIRC from the other page.
Chum_lee
Explorer
May 17, 2019
"My assumption is that the power cord for the trailer is 10-gauge. 50-foot RV extension cables are also 10-gauge. This jives with the chart I looked up... BUT"

STOP assuming. Instead, LOOK at the cable. The wire gauge is printed on the cable insulation. (at least it was when it was new) There's your answer. If the printing/embossing is no longer visible, pull the cover off the j-box where the cable connects just inside the RV. Look at the wire.

"Am I just over-thinking this?"

No. IMO, You aren't thinking at all. You are reacting.

Chum lee
2oldman
Explorer II
May 17, 2019
10 gauge should be fine, I run 60' of it running air con and it's fine. From what I see on Amazon, if you want to go 8 or 6 gauge, you'd need a 50a extension.

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