Extension Cord

SoundGuy wrote:


I'd go remeasure each of the 1/2 dozen electric heaters I own but guess what - I don't have to "back up" anything and frankly don't care whether you believe it, or not. :p FACT is, only one of my heaters that are labeled as "1500 watt" draws anywhere near that much, ALL the rest pull much less.

You muddied the waters by bringing up that heaters put out a fair bit less than their rating. I recommend reading the UL standard for portable electric space heaters which covers construction details, testing and labeling. Do you know what the OP's heater might put out?

The OP's original question was whether 100' of 12 gauge drawing from a 15 amp circuit would be suitable for his intended use and the answer is YES. Even assuming a maximum draw of 15 amps voltage drop over that 100' of 12 gauge would only be 4.76 volts.

What you are ignoring is the overall length of what the circuit could be. Is it 200', 250' or maybe 300' and how much is #14 ga? It's also important to take into account the starting voltage at the source. Not knowing either, nobody can assure that #12 is adequate for an extension cord - you cannot look at 100' of extension cord in isolation and assume that the starting voltage is 120 volts.

For example: Say the wiring in the house was 100' of #14 panel to plug (or whatever it is being plugged into), the extension cord is 100' of #12 and the shore power cord is 25' of #10, at a starting voltage at the source of 120 volts at a draw of 15 amps, the voltage would be down to 106.9 volts in the RV for a drop of 11%. Even then, that ignores what the wiring from the house's panel is to the street, how long and what gauge, which could (and sometimes does) affect voltage drop. I don't think the OP has provided adequate info. to make a definitive determination. If someone want to try and save $50 or so to take a gamble, that's up to them.