Hi,

I am thinking about laying an extension cord across the ground to add a heat lamp for a chicken coop in the back yard. Thinking about a 250 or 300 watt heat lamp, 100 watt overhead light and 100 watt water heater for winter. The distance would be 200'.

Would a regular extension cord work for that or do I need something "heavy duty"?

Thanks!

A "regular" 12 gauge conductor extension cord would work at that distance without much voltage droop. Fortunately everything you are wanting to run here is resistive, so no problem. Now if you wanted to run a motor, things could get interesting and would require a bit more figuring.

EPM

At 120 V, 500 W is 500/120 = ~4.2 amps. A 12 AWG cord will give a little less than a 3% drop, so I agree with the 12 AWG wire for that load.

What bothers me is that you would want this protected by a GFCI and you probably will have a hard time finding 200' of a single extension cord. The spice would have to be done in a dry location away from snow and rain to stop tripping the GFCI.

These guys make some nice high quality cords: http://www.woods.com/files/Cords_and_Lights.pdf

Or make your own: 3 conductor SJOW or SJOOW SJOOW Portable Cord-Large Selection-Cut to Order and add a plug and cord connector.

Portable cord - Wikipedia, the free encyclopedia

The W is mandatory for your application.

Still don't recommend it.