4.4 Generators, backfeed, carbon monoxide — and the first minute after a shock

1 A generator is a temporary power system

OSHA's fact sheet on portable generators states the principle before any of the details: "The electricity created by generators has the same hazards as normal utility-supplied electricity. It also has some additional hazards" (FS-3286). Everything from Part 3 applies to what comes out of a generator — GFCI protection or an assured grounding program, three-wire hard-usage cords, guarded lamps, nothing on the floor.

The fact sheet's own list is short and worth quoting as a checklist: plug appliances directly into the generator using the manufacturer's cords or grounded three-pronged extension cords; inspect the cords for damage; make sure they are rated for the intended use and not underrated; do not overload the generator, which can lead to overheating and a fire hazard; use GFCIs, especially where equipment is used in or around wet or damp locations; keep the generator dry and protect it with a canopy if needed; never manipulate a generator's electrical components while wet or standing in water; and do not use electrical equipment that has been submerged until it has been dried out and properly evaluated.

2 Backfeed: the hazard that leaves the site

The one generator mistake that endangers strangers is connecting it to a building's wiring through an outlet. OSHA FS-3286 is explicit: never attach a generator directly to the electrical system of a structure unless a qualified electrician has properly installed the generator with a transfer switch, because doing so "can energize wiring systems for great distances", creating "a risk of electrocution for utility workers and others in the area."

FS-3942 adds the operational step: be sure the main circuit breaker is off and locked out before starting any generator, to prevent inadvertent energization of power lines from backfeed and to help protect utility line workers from electrocution.

Backfeed also matters inside the fence, and Chapter 2 of this part explained why: it is one of the two conditions 1910.333(b)(2)(iv)(B) requires a qualified person to test for before declaring a circuit dead. A generator someone tied in without a transfer switch is exactly how a locked-out circuit becomes energized again.

3 Carbon monoxide

Carbon monoxide is "a poisonous, colorless, odorless and tasteless gas" produced by incomplete burning of carbon-containing fuel, and OSHA's fact sheet names the internal combustion engine as one of the most common workplace sources (FS-3522). It harms by displacing oxygen in the blood and depriving the heart, brain and other vital organs; "large amounts of CO can overcome you in minutes without warning — causing you to lose consciousness and suffocate."

Initial symptoms include tightness across the chest, headache, fatigue, dizziness, drowsiness or nausea. With prolonged or high exposure: vomiting, confusion, collapse, loss of consciousness and muscle weakness. OSHA's permissible exposure limit for CO is 50 parts per million as an 8-hour average.

The generator rules follow from the physics. OSHA Alert 4105: never use a portable generator indoors or in enclosed spaces such as garages, crawl spaces and basements; use it outdoors, but never near doors, windows or ventilation shafts where CO can enter and build up; give it 3 to 4 feet of clear space on all sides and above. FS-3286 adds the sentence that ends most arguments on site: open windows and doors may not prevent CO from building up when a generator is located in an enclosed space.

4 Fuel, heat and the rest of the machine

5 The first minute after an electrical injury

This is the sequence from Part 1, put where you will need it. Two of the three natural instincts — reach for them, check on them before cutting power — are the ones that produce a second casualty.

1. 1
   Cut the power. Disconnect, breaker or plug — whichever is fastest and safe to reach.
2. 2
   If you cannot, use a dry nonconductor. A board, a pole, a stick of wood or other nonconducting material, to push or pull the person clear — never your hands, never their clothing.
3. 3
   Protect yourself. OSHA 3075: act quickly, but remember to protect yourself as well from electrocution or shock.
4. 4
   Call for emergency medical help every time. Internal hemorrhage, tissue, nerve and muscle destruction and renal damage are invisible; a person who says they are fine still gets seen.
5. 5
   For a suspected CO exposure: move the person to fresh air in an open area, call 911, and do not re-enter until someone trained and properly equipped determines it is safe. OSHA's own warning: "You may be exposed to fatal levels of CO poisoning in a rescue attempt."
6. 6
   Take the equipment out of service and leave the scene. The cord, tool or panel is still a hazard, and it is also the only evidence of what happened.

6 What this course was for

You will not leave this course qualified, and that was never the goal — 1910.399 requires demonstrated skills on equipment, judged by someone able to judge them. What you should leave with is a working boundary: a clear sense of which side of it you are on, what the standards oblige your employer to tell you and give you, and which four or five habits carry most of the protection.

Look up before anything long goes up. Look at the cord before you plug it in. Ask for the boundary when a panel is open, and stay behind it. Do not help. And when a circuit is supposed to be dead, remember that a qualified person with a tester is the only thing that makes that sentence true.