This is to amplify a bit on Hal's post. I installed an electric jack last summer because I simply got tired of getting all sweaty while hooking up/unhooking on a hot summer day. Although I'm in excellent health with a pretty strong upper body (I work out 3 days a week), I found the electric is faster than by hand and I don't need a shower/change of clothes when I'm done...something that was inevitable after a use of the hand crank.
I got the heavy duty one that Hal refers to...it has a work light and a 3000 lb rating. Camping world has an excellent price (only $189) for their President's Club Members (compared to other 'net retailers who want around $230)...see it at
http://www.campingworld.com/browse/s...m?skunum=20051 Note that it comes in a 2 inch and 2.25 inch size...the 2 inch size is the correct one for the TM hitch (leastwise my 2720SL's swingaway hitch)...this size was a direct bolt in replacement that needed no grinding or other modifications to the TM to mount it.
WRT to installing it, yes, one should be bit careful on the electrical issues. First of all, it pulls around 20 to 25 amps so (as Bill and Hal both indicated), it should NOT be used when the TM's converter is powered up by shore power as it definitely could overload/burn out the battery charger section of the converter. I personally didn't find this a major issue as I only use it while unhooking (before the TM is opened up and shore power hooked up) or while hooking up for departure (after the TM is closed up with the shore power cable disconnected & stowed). I have used it when the umbillical to the Tow Vehicle is still attached with no ill effects...though this was with a circuit breaker in the TV's power supply cable.
Given the above self-imposed safety limitations, I
did hook mine directly to the TM battery using 10 GA wire and a 30 amp self-resetting circuit breaker right at the battery. I chose a circuit breaker instead of the supplied fuse as my battery is in a rear compartment that can't be accessed when the TM is closed up. It is possible to pop the circuit breaker if one switches direction on the jack before it has stopped moving the other direction.
Finally, this jack obtains it's electrical ground through one of attachment bolts. I personally wasn't confident that my TM's swing away hitch pivot pin would provide a reliable, low resistance ground return path from the swinging part of the hitch back into the trailer's frame. So I installed a separate ground wire between the two sections of the hitch.