Snakes Under Houses and Inside Equipment
Why this matters
Snakes go where the mice go and where it is cool in summer and warm in spring: crawlspaces, the base of a condensing unit, pool equipment pads, irrigation and meter boxes, woodpiles, stacked block, the gap under a shed floor. Trade techs work in all of those, often by reaching in before looking. NIOSH puts venomous bites in the US at roughly 7,000 to 8,000 a year with about five deaths, so a bite is survivable when it is handled right. Handled wrong, with a tourniquet, a knife or a two-hour wait to see whether it swells, it costs a hand or worse. The protection is a flashlight and a habit. The response is calm, still, and 911.
Which snakes, where
The venomous snakes in the US fall into two families.
Pit vipers, recognized by a heat-sensing pit between eye and nostril, a broad triangular head and vertical pupils (all of which you should be seeing from well back, not up close):
- Copperheads: the East, Southeast and south-central states. Tan to copper with darker hourglass bands. They account for the largest share of US venomous bites, largely because they are common around houses, freeze rather than flee, and are well camouflaged in leaf litter.
- Rattlesnakes: many species across most of the country, most diverse and most common in the Southwest and Texas, with timber rattlesnakes in the East and pygmy and eastern diamondback rattlesnakes in the Southeast. Not every rattlesnake rattles before striking.
- Cottonmouths (water moccasins): the Southeast and the lower Mississippi valley, around water, ditches and wet crawlspaces. Many harmless water snakes are mistaken for them.
Coral snakes, small, brightly banded red, yellow and black, in the Southeast, Texas and Arizona. Their venom acts on the nervous system and symptoms can be delayed for hours, so a coral snake bite that "looks fine" is still an emergency. The color rhymes that supposedly separate them from harmless mimics are unreliable; treat any banded snake you are unsure of as venomous.
Most snakes a tech meets are harmless: rat snakes in crawlspaces after mice, garter snakes, kingsnakes, water snakes. That changes nothing about the method, because the method does not depend on identifying the snake.
How bites happen
Most bites come from two situations: reaching or stepping where you cannot see, and trying to move, catch or kill a snake. The second is a choice; a large share of bites happen to people who were trying to deal with the snake.
Snakes strike over a short distance, and the rule of thumb often given is up to about half their body length, so keep well beyond the length of the snake. A snake that looks dead can still bite: reflex bites from dead and even decapitated snakes are documented, so a snake fried in a contactor or killed with a shovel is handled with a tool, never a hand.
Where trades meet them, and the habit for each
Crawlspaces. Before entering, sweep the space with a strong light from the access, slowly, including along the sill plate, around piers, under ductwork and near the access itself where snakes rest in the shade of the door. Repeat the sweep each time you move forward. Gloves, long sleeves, boots. A crawlspace with standing water raises the odds of cottonmouths in the Southeast. The full pre-entry check covers this and more. See related: The Crawlspace Entry Hazard Check SOP.
Condensing units, heat pumps and pool equipment. Snakes shelter in the base and around warm compressors and pump motors, and a snake bridging contactor terminals is a known cause of a unit that suddenly quits and a scorched contactor. Light through the louvers before opening a panel. If there is a snake inside, close it up, keep the unit off, and wait or call for removal; running the unit will not drive it out and starting the fan beside it is a fast way to have an agitated snake at hand height. If the snake is dead in the electrical compartment, de-energize at the disconnect, prove the terminals dead with a meter proved on a known live source before and after (NFPA 70E-2021, 120.5; work practices at OSHA's 29 CFR 1910.333(b)(2)), and remove it with long pliers or a stick.
Valve boxes, meter boxes, sumps and pits. Lift the lid with a tool, standing to the side, and look before reaching. A valve box lid is lifted toward you only after you have seen under the near edge.
Woodpiles, block, lumber and debris. Lift from the far side so the material shields you, with gloves, and never reach under a pallet or a stack.
Grass and brush. Boots and long pants, watch where you step, and step on top of logs rather than over them, since a snake resting on the far side gets your ankle.
If you find one
Back away slowly to well beyond its length and leave it a path out. Do not try to kill it, move it with a tool or trap it. Tell the customer and the office. Many snakes leave on their own within the hour; if it is in a crawlspace or inside equipment and needs to go, a wildlife removal operator does it. Note on the job record where it was, because a snake in the crawlspace usually means rodents in the crawlspace.
If someone is bitten
The protective actions come first and they are the whole of the field response. This follows NIOSH's guidance for workers.
- Get away from the snake, and get everyone else away. Do not go after it to identify it. If you can photograph it from a safe distance, fine; do not try. Remember its color and shape.
- Call 911 immediately. Do not wait for swelling or pain to decide. Some bites inject little or no venom, but nobody can tell which in the first minutes, and coral snake symptoms can be delayed by hours.
- Keep the person still and calm, sitting or lying down. Movement speeds the spread of venom. NIOSH says to keep the bite below the level of the heart. Do not let them walk out of a crawlspace on their own if they can be helped out.
- Take off rings, watches and tight clothing near the bite before swelling makes it impossible.
- Cover the bite with a clean, dry dressing.
- Tell the office, which tells the customer and gets someone to the hospital to meet the tech.
Do not: apply a tourniquet, cut the wound, try to suck out venom, apply ice or soak it in water, give alcohol or caffeine, or pick up or try to catch the snake. Every one of these is old advice that either does nothing or makes the injury worse. Antivenom is given at the hospital; species identification helps but is not required for treatment to start.
DISPATCH: 911, what's the address of your emergency?
HELPER: 1418 Pine Hollow Road. My coworker was bitten
by a snake on his right hand, about a
minute ago. Copper colored.
DISPATCH: Is he awake and breathing?
HELPER: Yes. He's sitting on the tailgate. I'm taking his
ring off. Hand's starting to swell.
DISPATCH: Keep him still. Don't cut it or tie it off.
HELPER: Okay. I'll be at the end of the driveway
to flag you down.
Address first, then what happened and when, then the person's condition, then what you have done. Sending someone to the road to wave the ambulance in saves real minutes on a rural lot.
Worked example: one week, two boxes, two outcomes
A lawn and irrigation company in east Texas, copperhead country, June.
Monday, the crawlspace. A tech goes under a pier-and-beam house to trace a leaking irrigation supply line where it enters the foundation. At the access, before entering, he runs a light slowly across the space. About 6 ft in, beside a pier, a coiled copperhead roughly 2 ft long sits in a patch of dry leaves that blew in through a broken vent. He backs away from the access and closes it. The office calls a removal operator, who arrives two and a half hours later and bags the snake. The tech traces the leak that afternoon. Cost: the morning lost on that stop. The note on the job also records the broken vent and fresh rodent droppings near it, which the customer gets a quote to fix.
Thursday, the valve box. A new helper, three weeks on the job, is told to open the valve box at the side of a house and shut off zone 4. He kneels, pulls the lid off with one hand and reaches in with the other without looking. A copperhead sheltering under the near edge bites him on the back of his right hand at 10:12.
The crew lead's sequence, timed from the incident report:
- 10:12 pulls the helper back from the box and walks him to the truck, sits him on the tailgate.
- 10:13 calls 911 using the address on the work order, as in the dialog above.
- 10:14 helper's ring and watch off; hand kept low and still.
- 10:15 clean dry gauze from the truck kit over the bite; calls the office.
- 10:16 with a marker from the cab, draws a line at the edge of the swelling and writes 10:16 next to it, so the hospital can see how fast it is spreading.
- 10:31 ambulance on scene; the crew lead hands over the time of the bite and a description.
Nobody cut, sucked, iced or tied off the hand, and nobody went back to the box to kill the snake. The helper is treated at the hospital and is back on light duty after several days. From bite to ambulance was 19 minutes (10:12 to 10:31), which is about as good as a residential call gets.
What would have changed the answer: if the helper had been working alone and the job were far out on a rural property, the same steps apply, and the call to 911 includes that he is alone and cannot drive. The single thing that would have prevented the bite was a lid lifted with a tool and a look under the near edge.
The change the shop made: every truck now carries a valve box key and a hook, and the new-hire ride-along includes opening a box the right way before anyone is sent to one alone.
References
- NIOSH, Venomous Snakes (species, prevention, first aid do and do not list, US bite and death figures)
- CDC, snakebite first aid and the case against tourniquets, cutting and suction
- OSHA, 29 CFR 1910.333 Selection and Use of Work Practices; NFPA 70E-2021, 120.5 (verifying absence of voltage)
- See related: The Crawlspace Entry Hazard Check SOP
- See related: Venomous Spiders in Crawlspaces and Sheds