Honestly, if you run thick enough gauge wire it's totally fine. At my shop we run some portable 220v miller welders off of 25' extension cords. Be it the cord is around 5/8 to 3/4" thick..30ft is a long way for an extension cord when its pulling a lot of amperage
If you're talking about one of those funky plugs used for fridges, washers, & dryers. The one with 3 flat prongs placed like their on the circumference of a circle. Then I suggest trying Home Depot. I kinda doubt if they have that end on a pre-made extension cord with a regular plug on the other, you'll probably have a better chance buying elecrical cord off the spool and having them put the ends on for you, they may have those plug ends to put on their cords.hey guys also will he extension cords i buy from hardware store work on 220v outlets?
i only use one 1000w hps on that cord and that cord is run all alone on its own circuit. with a circuit breaker.how many watts ballast are you running that extension with?