Generators and Temporary Power

Temporary power is where most site shocks happen, because it is put in fast, moved often, and nobody owns it.

Backfeed

Never connect a generator to a building's wiring through an outlet — a "suicide cord" with male plugs on both ends. It energises the building's circuits, then goes back out through the service to the utility transformer, which steps it up to distribution voltage on the line outside.

That kills the lineman working on a line everybody believes is dead, and it kills whoever touches a downed conductor down the street. A permanent connection requires a transfer switch, installed by an electrician. There is no safe version of the cord.

Siting a generator

• Outdoors only, well away from doors, windows and air intakes. Carbon monoxide from a generator kills people every winter, and the ones who died usually thought a garage with the door open counted as outside.
• Dry, level, and out of the traffic route.
• Shut it down and let it cool before refuelling. Petrol on a hot manifold ignites.
• Grounded per the manufacturer. Most portable generators with bonded neutrals do not need a separate ground rod when nothing but cord-connected equipment is plugged into them — read the manual rather than guessing in either direction.
• Do not overload it. Loose, warm or discoloured connections mean stop.

Cords and boxes

• GFCI on every 125-volt, 15, 20 and 30 amp receptacle used for construction — 1926.404(b)(1)(ii). On a generator that means GFCI receptacles or an inline GFCI, and it means testing them.
• Three-prong plugs with the ground pin intact. A cord with the ground pin snapped off is bin material, not "the one for the light".
• Rated for hard or extra-hard use outdoors, and the right gauge for the length — a long thin cord runs hot under load.
• Out of water, out of walkways, and never through a doorway that closes on it.
• Never staple, nail or hang a cord on rebar, pipe or a nail. Hooks or insulated hangers.
• Inspect before every use. Cuts, taped repairs, exposed conductors, a cracked plug body, a hot connection. Taped cord is not repaired cord.

Panels and boxes

Covers on, unused openings plugged, breakers labelled, and three feet of clear working space in front of anything you might have to open in a hurry. Water and temporary power is the combination that kills — if a box has been rained into, it goes out of service until somebody qualified says otherwise.