length of 30 amp line

I have roughly a 25-foot shore power cable for my trailer and have added an additional 25-foot M-F extension shore power cable (same size) without any problems...

Some camground pedestals will be just inches away from allowing the shore power cable to reach the pedestal so I carry the additional M-F extension shore power cable just for this reason...

Roy Ken

120V 30A 3% Voltage Drop

#10 wire------25'
#8 wire------50'
#6 wire-----100'

I keep my camper plugged in at home on a 50 foot wire, 24x7. Before I installed a surge protector inside the camper, the trailer had 35 feet of cord. Depending upon which way I turned the trailer, it took either an additional 25 foot, or an additional 50 foot. So, I had either 85 feet total, or 60 feet total. So, 50, 60, and 85 at home. I've NEVER had any problems.

Now, I also have two 50 foot cords, and two 25 foot cords, and the original 35 foot from the camper. I have on a couple occasions used it all at home when I parked in the front yard. That's a total of 185 feet of cord, and the camper ran just fine.

Normally, I'm running through a 50 foot cord, and I use the 25 footer at campgrounds if the pedestal is right at the campsite.

Anywhere we've been in the US I've never run out more than 50' but here in the Ontario provincial park system having to run out at least 75' isn't unusual at all, even 100' is quite common. :E I carry ~ 140' of 10 gauge cable and last year used it all at Inverhuron Provincial Park where really long runs are the norm. When push comes to shove no one needs to pull a full 30 amps, in fact we typically only draw a few amps to power the trailer itself and restrict our maximum draw to not much more than 15 amps total by only running one high draw device at a time. For example, if we want to use the microwave oven and the A/C happens to be on I'll either turn it off completely or dial back the thermostat so only the A/C fan motor is running. During cold weather when we may be using an electric heater to augment the furnace we'll turn it off briefly if my wife wants to use her hair dryer. Long runs are so typical here it's also the reason I usually run our water heater on gas only and don't bother with the electric heating option unless we happen to get lucky and are on a site that only requires a 25' run to the power post, which doesn't happen often. Restrict your maximum draw, check your unloaded source voltage before plugging in, and monitor the voltage with the circuit under your expected maximum load to ensure incoming source voltage doesn't all below ~ 105 vac and you'll be surprised at just how far out you can run your 10 gauge main service cable. OR better still, protect your trailer's electrical system with a Progressive Industries EMS-HW30C surge protector that will prevent campground power source anomalies from damaging your trailer, including excessively low voltage by cutting it off completely when it drops below 104 vac.

Probably depends on what the draw is, if only keeping the battery and frig going, quite a ways. If you are drawing all 30 amps -- AC, microwave, coffee pot, toaster, television, water heater and all other appliances on @ the same time then not very far. So a lot depends on the end usage. JMHO

As long as you do not run A.C. or microwave it can be purty darn long . That said , there are many, many variables , we just spent three nites plugged in at a place that only gave us 104 volts to begin with .

I sometimes use my home made 100' 10AWG 30A cable, plugged into my permanently attached 30' 50A cable. As long as I am careful with my power management .. ( e.g. don't try running MW at same time as AC,) everything is just fine.... voltage stays well into safe range.... assuming shore power pedestal has good wiring to begin with.

Great info y'all. Thanks a lot.

Old-Biscuit wrote:
120V 30A 3% Voltage Drop

#10 wire------25'
#8 wire------50'
#6 wire-----100'

I'd be interested in knowing the source of this information as this Voltage Drop Calculator which is particularly easy to use indicates a considerably different result, as shown in this screenshot.



However, even more pertinent to this discussion is the fact that if one halves maximum current draw from 30 amps to 15 amps then cable length can double, as I typically so often do by limiting our use of high draw devices to just one at any given time.

Several items change the acceptable length: Generally, you need sufficient voltage at the device you are powering. The longer the cable, the more the voltage drops but there are other factors that can come into play:
- What is the voltage at the pedestal? I've seen everything from 107V to 126V. At the lower end, I would be hesitant to run most anything. At the upper end, you can probably get away with a pretty long cord.
- What size are the conductors in the cable? Most are standard but you can get an upsized cable. Bigger conductors reduce voltage drop.
- What are the power draws? The more amps drawn the bigger the voltage drop. If you are just running the fridge, you can get away with a much longer cord. If you run the fridge, air/con, several lights and get up near the limits, the acceptable length gets shorter.

We have a voltage monitor we plug into an outlet in the kitchen ($25 at home depot). It's easy to see and just stays plugged in. As long as the voltage stays above 110v, I don't worry too much but it's a good idea to check when the air/con or other heavy load kicks on that it doesn't drop too low. It will dip for a second during startup of the compressor but shouldn't go too low and should quickly rebound to 110v or better.