A 15 A tool on a 12 AWG cord run out to 150 ft is within current rating but the voltage drop climbs past 5% — long runs need heavier wire or a shorter cord.
Stop and call a licensed electrician or emergency services now if there's smoke, sparks, a burning smell, heat, shock, or water near the problem. Otherwise it's safe to answer the questions below.
The likely readout
Most likely cause
12 AWG at 150 ft, ~15 A: 6.0% voltage drop — inadequate (cord heats, tool runs low)
Ranked by fit to your answers
1
Inadequate — excessive voltage drop (cord heats, tool runs low)
90
SAFE NEXT CHECKDrop of 6.0% means heat in the cord and low voltage at the tool (hard on motors). Step up to about 10 AWG (and even then, shorten the run or split the load at this length) for this length, or use a shorter cord.
Where to stop. Choosing or replacing an extension cord is homeowner-safe. Manufacturers and fire authorities advise plugging high-draw heating appliances such as space heaters directly into a wall receptacle rather than any extension cord. Anything involving the building's wiring or circuit rating is a licensed electrician's job. This is general information, not a quote and not a substitute for a licensed electrician.
Try the safe next check above. If it doesn't resolve it, or would mean working on wiring or a panel, stop and call a licensed electrician — don't replace parts on a guess. Open the full tool to change any answer for your exact situation, or try a related check below.
Electrical Fault Check provides general diagnostic information only. It is not professional advice, not a quote, and not a substitute for a licensed electrician. Do not work on live wiring. If you see smoke, sparks, burning smell, heat, shock, water exposure, or repeated tripping, stop using the circuit and contact a licensed electrician or emergency services as appropriate.