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How NOT to Connect a Portable Generator

posted Dec 2, 2012, 7:01 AM by Bob Wallace

Beware of Backfeeding

Jim, the Generator Expert
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Beware of Backfeeding
EDITOR'S NOTE: This article was submitted by Rick Berry, the Electrical Safety Officer in the Greater Victoria area, in Vancouver, Canada.

Part of our inspection duties includes assisting the fire departments in determining fire causation when the suspected cause might be electrical.

For some background, our area at times here is subject to wind storms coming in off of the Pacific Ocean, even being called 'The Pineapple Express' when a particularly heavy wet (rainy) storm comes up from Hawaii.

This particular storm was of a way longer duration and of stronger winds than normal and also followed several weeks of heavy rain that soaked the ground. The strong winds combined with the soaked ground caused a huge number of trees to fall throughout the area, taking out the overhead power lines with them.

The local Utility was swamped with trouble calls and 'seconded' all the private utility line contractors to assist them, but it still took time (some were out as long as 6 days!). Unfortunately, some people decided that they couldn't wait for the power to come back on and they took matters into their own hand, so to speak.

This place is in a rural area and was already equipped with a stand-by generator, wired correctly with an approved transfer switch, however it was sized for the minimum of loads (fridge, well, septic, freezer) This owner was having his staff Christmas party at his house and needed "...a bit more power..." for the big screen TV, karaoke machine, sound system and flashing lights!!!

Being that he was somewhat of a 'handy guy', he went to one of the local tool rental companies and rented out their last generators. Getting it home, he now had to 'hook it up' to get the party started.

He looked at the generator output receptacle and realized that he had a cable in his shop with the same end on it! HEY, not only did he have a cord with the right end, but his electric arc welder outlet in the garage of the house matched it too!

His lucky day? NOT !!!

He proceeded to take the cord off of his welder and installed the other receptacle on the end, yes... they are both MALE receptacles! He plugged one end into the generator, the other into the welding outlet on the garage wall, and being a 'smart guy' went to the main panel and turned off any breaker feeding devices and equipment he didn't need... except, he left the main turned on...

The generator seemed to give him a 'few problems' while it was running, but he made it work (all assisted by his other neighbour turning THEIR main breaker off when their lights started 'flickering' (back fed from the neighbours generator?)

When the power was restored to the area, the neighbour noticed that the streetyard lighting from his neighbours shop was on, but he could still hear the generators running... for a few minutes.

As he was getting ready to walk over and let his neighbour know that he could turn his generators off and run his party at 'full power', he said there was a loud 'WHOMPFFFF' from across the field and then the sky lit up !

Thinking at first that there was fireworks (there was... but not 'that' kind) he went back in his house to wake up his kids... by the time he came out, the 'rented' portable generator, the side of his neighbours house, the neighbours motor home/race car hauler, boat and his wife’s SUV were burning.

As near as we could figure from piecing together the story (and the molten pieces of equipment) when the electrical service was re-energized by the utility it took them three tries to get their fuse and switch to hold in; but by that time the generator had melted/shorted 'shooting' flames out from the alternator windings!

Backfeeding Caused This FireThe flames caught the rubber tires on fire which then engulfed the generator with the top mounted gas tank (we think that was the first 'WHOMPFFFF') The flaming gas then ran down the slope of the driveway to the race car hauler... by then, it was 'All over but the crying.'

We (the local fire departments and our inspection office) use this story at any chance we get to prove that here in Canada, insurance companies will even cover stupid!

Thank you to the experts at!