What size extension cord gauge would I need for a 12 amp electric mower if the cord is 250 feet long?

Question

I need to use an electric mower for my very large yard because I can't start a gas mower and my nearest neighbor is about 5 miles away. Living on a limited budget, I can't find anyone to cut the grass for what I can afford to pay. My yard is about an acre with about 30 trees. It has heavy dense grass. The extension cord would need to be at least 250 feet long to reach to the edge of the yard. My question is what gauge wire would I need to use to make the extension cord? The mower that I'm thinking about buying is a 12 amp mower. The circuit breaker for the plug at the house is a 20 amp breaker. Are there other things that I need to take into consideration? And if you have suggestions for a mower that would work well for these conditions, I'm open to suggestions.

Answer 1

A Gas lawnmower with an electric start. Electric ones don't like to cut heavy dense grass. Plug it in at the house, start it, disconnect and go. A quick search found a self-propelled one for about $300. I couldn't really find one much cheaper but I do recommend a self propelled model. Like this one from Briggs and Stratton, a reputable company.

-Home Depot

If you're not just going to plug a bunch of regular cords into each other, a legitimately constructed cable and an electric mower would near, if not surpass, the cost of one of these more effective machines.

Answer 2

I really think you're going to be unhappy with an electric mower for this situation, for a couple reasons:

• 250 feet of extension cord is going to be expensive, heavy, and very unwieldy to mow with
• Electric mowers are not that powerful and mowing a full acre is going to be a long, hard slog. I would guess it would probably take you two hours of hard work.

Having said that, a 12 GA extension cord (very large) will have about 8% voltage drop, which I would say is only borderline acceptable. Anything smaller than that will loose so much voltage that the mower will barely work. Based on a quick check online, it seems like you're looking at $100 - $150 (plus the cost of the mower, of course).

One thing to consider is shrinking the size of the yard that you keep mowed, and letting the rest of it grow. Maybe you can pay someone to cut the whole thing only once a year, to keep it from getting out of hand.

Also, I don't know what exactly your reason for saying you can't start a gas mower: not sure if you physically can't pull hard enough or just feel like you don't have the right skill set for a small engine, but I have a newish Toro self-propelled mower that starts on the first pull every time. Every time. It's been the easiest small engine I've ever used.

Answer 3

You can find a voltage drop calculator here.

With your scenario, you would drop about 10% of the voltage, leaving 90% for the mower. This is on the edge of acceptable assuming that the voltage at the outlet is a full 120 volts, but if it's lower the voltage at het mower would be marginal.

In that case, going to a 10 gauge cable would drop the voltage drop down to only about 7%. However, a good-quality 10 gauge 100' extension cord is going to be pretty price - at least $100.