Fallen power line on your house, roof, or metal fence¶

When severe windstorms, ice accumulation, falling tree limbs, or transformer explosions snap an overhead electrical utility wire and drop it onto your house roof, rain gutters, aluminum siding, or backyard chain-link fence, your property instantly becomes part of an energized high-voltage circuit to earth. Unlike indoor household wiring, which operates at 120/240 volts (or 230 volts in Europe) and trips a circuit breaker within milliseconds of a short circuit, overhead utility lines carry between 240 volts (service drop) and 4,000 to 34,500 volts (primary distribution feeders). Worse still, utility substation circuit breakers (called automatic reclosers) are specifically programmed to automatically re-energize a downed line two to four times over several seconds or minutes to burn clear temporary tree branch faults.

Because dry asphalt roof shingles, wooden rafters, soil, and concrete have high electrical resistance, a 13,800-volt primary distribution wire resting quietly on your roof or backyard fence often does not draw enough fault current to blow the utility pole fuse. Consequently, the wire remains silently energized at lethal voltage while energizing metal rain gutters, copper plumbing, aluminum siding, and 100+ meters (330+ feet) of interconnected neighborhood chain-link fencing, while radiating concentric rings of voltage (step potential) through the surrounding ground. This comprehensive guide covers immediate shelter-in-place versus evacuation decisions, neutral wire backfeed fire mechanics, metal fence touch-potential lethality, and the shuffling-foot evacuation technique.

Do this now¶

If an overhead utility wire, transformer, or service drop mast pulls loose and falls onto your house roof, siding, driveway, or yard fence, execute these six steps immediately:

1. Treat every fallen wire as live and lethal, even if it is not sparking: Never assume a downed wire is a harmless telephone, fiber-optic, or cable TV line, and never assume a silent electric wire is dead. Automatic utility reclosers can send 13,800 volts surging back into a quiet wire without warning.
2. Stay inside your house unless the structure is actively on fire: If a power line is resting on your roof, porch, or driveway and there is no smoke or fire inside, stay indoors away from exterior walls. Walking out your front door onto wet concrete steps or damp grass puts you directly inside the ground-voltage gradient zone and beneath energized rain gutters.
3. Call 911 / 112 / 999 AND your electric utility's emergency dispatch immediately: Call your local emergency numbers (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) and report "A downed utility power line is resting directly on my house/fence." Immediately afterward, call your electric utility's 24-hour emergency outage hotline so their grid control center can de-energize and ground the feeder line.
4. Do NOT touch your main electrical breaker panel, plumbing, or metal appliances if the service drop is damaged: If a primary high-voltage line fell onto your low-voltage house service drop, or if the neutral wire snapped, your metal breaker box door, copper water pipes, and grounded appliances can be energized at hundreds or thousands of volts. Stay completely away from the electrical panel, sinks, and metal doorframes.
5. Stay at least 10 to 15 meters (35 to 50 feet) away from any fence, tree, or puddle touching a downed line: If a wire falls across a metal chain-link fence, wrought-iron gate, wire livestock fence, or wet tree branch, the entire continuous length of that fence is energized at lethal voltage, even three houses down the street.
6. If the roof catches fire and you must evacuate, shuffle or hop with both feet together: If smoke, crackling arcs, or flames force you to evacuate the house while a line is down on the property, exit through a doorway on the opposite side of the house from the wire, do not touch metal railings or storm doors, and shuffle your feet together without lifting them until you are at least 15 meters (50 feet) away.

Tactical decision tree for a fallen power line on a house or fence¶

Use this operational decision tree to determine within seconds whether to shelter inside your home or execute an emergency ground-gradient evacuation.

flowchart TD
    Start["Utility Line Fallen on House Roof, Siding, Tree, or Yard Fence"] --> Location{"1. Where are you right now?"}

    Location -->|"Outside in the yard or street"| OutDist["Retreat Immediately to 15 Meters (50 Feet) Clear of Wire, Fence, and Puddles"]
    Location -->|"Inside the house"| FireCheck{"2. Do you smell smoke, hear wall arcing, or see fire inside the house?"}

    OutDist --> FenceWarn["Guard Perimeter: Warn Neighbors NOT to Touch Any Connected Metal Fence or Gate"]
    FenceWarn --> CallDispatch["Call 911 / 112 / 999 and Electric Utility Emergency Number"]

    FireCheck -->|"No: House is quiet with no smoke or fire"| ShelterIn["STAY INSIDE: Move to Interior Room Away from Exterior Walls & Windows"]
    FireCheck -->|"Yes: Roof/attic smoking or wall outlets sparking"| EvacPrep["EMERGENCY EVACUATION REQUIRED: Choose Exit Door Furthest from Fallen Wire"]

    ShelterIn --> HandsOffInside["Do NOT Touch Main Breaker Panel, Metal Faucets, Water Pipes, or Plugged-In Appliances"]
    HandsOffInside --> CallDispatch

    EvacPrep --> DoorCheck["Open Door Without Touching Metal Storm Door Frame, Aluminum Siding, or Downspouts"]
    DoorCheck --> JumpShuffle["Hop Clear of Threshold with BOTH Feet Together; Shuffle Feet 15m (50ft) Away"]
    JumpShuffle --> CallDispatch

Anatomy of overhead utility poles: what fell on your house?¶

Understanding which wire snapped from the utility pole in front of your house helps you report the exact severity of the emergency to fire and utility dispatchers. Utility poles are arranged vertically by voltage, with the highest-voltage wires at the very top and low-voltage communication cables at the bottom.

UTILITY POLE HIERARCHY & HOUSE SERVICE DROP ANATOMY:
   [Utility Pole]
      (o)---(o)---(o)  <-- LEVEL 1: Primary Distribution (7,200V to 34,500V - LETHAL)
           |
        [=====]        <-- LEVEL 2: Pole Transformer (Steps down to 120/240V)
           | \
           |  \===(Triplex Service Drop: Two 120V Hots + Bare Neutral)===> [Roof Weatherhead Mast]
           |                                                                       ||
           +------(Black Coax / Fiber / Phone Cable)---------------------> [House Wall Box]

Why a downed power line on your house can set walls on fire from the inside¶

When a tree limb falls across the overhead triplex service drop running between the street pole and your roof's steel weatherhead mast, three dangerous electrical faults can occur simultaneously inside your home's framing:

1. Pulled-out meter base and energized rain gutters¶

When a heavy tree limb yanks the overhead triplex cable downward, it rips the steel conduit mast loose from your roof eaves and pulls the exterior electric meter socket box partway off your siding.

• Energizing aluminum siding and rain gutters: As the pulled service entrance wires scrape across the sharp sheet-metal edge of the weatherhead, metal roof flashing, or aluminum rain gutter, the black rubber insulation slices open. Because this fault occurs on the utility street side (line side) of your main circuit breaker panel, your house's 200-amp main breaker cannot trip to stop it.
• The bare 120/240-volt wire feeds hundreds of amps directly into your metal rain gutters, aluminum downspouts, and metal siding. Anyone standing on wet ground outside who touches the downspout or metal storm door completes the circuit to earth and is fatally electrocuted.

2. The "Open Service Neutral" hazard: why plumbing pipes and walls catch fire¶

In North American 120/240-volt split-phase systems (and many international TN-C-S / PME grounding systems), the bare silver steel cable in your overhead service drop is both the physical support rope and the neutral return conductor.

• What happens if the bare neutral wire snaps while the two black 120V hot wires stay connected:
• Wild voltage swings occur instantaneously across your house outlets: half of your 120-volt outlets drop to 30 volts, while the other half surge to 200 to 230 volts, causing surge protectors, microwave ovens, furnace boards, and power strips to pop and burst into flames inside rooms.
• Unbalanced return current flows through your copper water pipes and gas lines: With the overhead neutral wire broken, all electrical current returning from your house tries to find a path back to the pole transformer through the earth via your grounding electrode wire connected to your copper water pipes. Your copper plumbing pipes, cast-iron drain stacks, and flexible steel gas connectors can overheat to glowing temperatures and electrify kitchen and bathroom faucets.
• Neighbors' neutral current flowing through your municipal water pipe: Even if your own breakers are off, if your neighbor's neutral wire is damaged, return current from their house can travel through the shared metallic underground street water main into your basement plumbing. Never touch metal water pipes, indoor faucets, or the main electrical breaker panel when service wires are down.

3. Primary-to-secondary cross-contact (High-voltage intrusion)¶

If a 7,200-volt or 13,800-volt primary wire at the top of the street pole snaps and falls across the lower 120/240-volt secondary service wires feeding your house, thousands of volts surge directly down your service mast into your main breaker panel. Household circuit breakers are only rated to interrupt 240 volts; 7,200 volts jumps straight across an "OFF" breaker gap in a continuous plasma arc, blowing outlet faceplates off bedroom walls and igniting wood studs inside the wall cavities.

Metal fence electrocution: why chain-link and wire fences conduct for blocks¶

One of the deadliest scenarios after a windstorm, hurricane, or ice storm is a downed power line resting on a backyard chain-link fence, wrought-iron perimeter fence, or agricultural barbed-wire / woven-wire fence.

1. Why the fence does not ground out the power line¶

Homeowners naturally assume that because steel chain-link fence posts are set in the dirt every 2.4 to 3 meters (8 to 10 feet), a power line falling on the fence will immediately short out into the ground and trip the utility breaker. In reality:

• Concrete post footings and dry or sandy top-soil have relatively high electrical resistance (often 50 to 500 ohms per post).
• A 7,200-volt line resting on a chain-link top rail may only push 15 to 40 amps into the soil, far below the 100- to 400-amp threshold required to trip a utility substation feeder breaker.
• Consequently, the entire continuous metal fence network, often spanning 5 to 10 connected backyards down an entire residential block, remains energized at thousands of volts for hours. A child, dog, or neighbor three houses away who has no idea a tree fell down the street can walk into their own backyard, grab their chain-link gate latch, and be electrocuted instantly because their wet shoes and body provide a lower-resistance path to damp earth (touch potential).

2. Step potential vs. Touch potential explained¶

When high voltage flows from a downed wire or an energized fence post into the earth, the electricity spreads outward through the soil in concentric circles, exactly like ripples from a stone dropped in a pond. Voltage is highest at the exact point of contact and drops off with every meter of distance.

CONCENTRIC VOLTAGE RINGS (STEP POTENTIAL) AROUND A DOWNED LINE OR FENCE POST:
          [Downed 7,200V Wire on Ground / Fence Post]
                          ||
               ( ( (   7,200 V   ) ) )
            ( ( (      5,000 V      ) ) )
         ( ( (         3,000 V         ) ) )
      ( ( (            1,000 V            ) ) )
                        [Foot A]  [Foot B] <-- Normal stride bridges 3,000V to 1,000V = LETHAL
                        [FootA+B]          <-- Shuffling feet together keeps voltage difference = 0V

How to evacuate a house safely if a downed power line starts a roof or wall fire¶

As long as your house is free of smoke, sparks, and fire, stay inside in an interior room until utility linemen confirm the line is de-energized and grounded. However, if a downed wire on your roof or siding ignites the attic rafters or wall studs and you smell smoke or hear crackling fire inside the house, you must evacuate immediately without getting electrocuted at the doorway:

1. Choose an exit door on the side of the house OPPOSITE the fallen wire: Look out the windows before opening any door. Never exit underneath the roof eave where the wire is hanging, and avoid driveways or patios that have puddles of water touching the foundation.
2. Check the doorframe and avoid touching metal trim: If you have a wood or fiberglass door leading onto a dry wooden porch or concrete step on the far side of the house, open the door using only the interior handle. Do not grab an aluminum storm door frame, metal screen door mesh, or metal porch handrail.
3. Hop clear of the doorway threshold with BOTH feet together: If you suspect the house siding, metal threshold sill, or porch railing is energized, do not step out with one foot inside the house and one foot on the ground outside (which bridges the house's voltage potential to the earth). Stand on the interior floor, tuck your arms against your chest, and hop with both feet pressed tightly together so you land on the ground outside with both feet simultaneously without touching the doorframe.
4. Execute the two-foot shuffle to 15 meters (50 feet):
5. Once outside on the ground, keep your feet pressed together side-by-side so your ankles touch.
6. Slide one foot forward no more than 5 to 8 centimeters (2 to 3 inches) along the ground without lifting your sole off the earth, then slide the other foot up to meet it, keeping both feet in continuous contact with each other and the ground.
7. Alternatively, hop like a bunny with both feet locked tightly together so only one point of ground contact exists at any instant.
8. Continue shuffling or hopping until you are at least 15 meters (50 feet) away from the house, the downed wire, any metal fences, and any wet ground.

Solar panels, backup generators, and post-storm electrical reconnection¶

Before power can be restored after a utility line falls on your house, two additional electrical hazards must be managed: rooftop solar photovoltaic (PV) arrays and portable backup generators.

1. Rooftop solar panels remain live in daylight even when the grid is down¶

If a falling tree limb or utility line crashes onto a roof equipped with solar photovoltaic (PV) panels:

• Even when the utility grid fails and your solar inverter automatically shuts down anti-islanding export (Rapid Shutdown), the individual solar glass modules and DC string wiring on the roof continue generating 30 to 600 volts of direct current (DC) whenever sunlight or bright daylight hits the cracked glass.
• Water from rain or fire hoses contacting shattered solar panels creates an immediate DC arc-fault fire and energizes metal roof racking and rain gutters. Report rooftop solar panels immediately to arriving firefighters.

2. Never backfeed a portable generator into a damaged house system¶

After a storm rips down your overhead service drop, never plug a portable gasoline generator into a dryer outlet or flip a generator transfer switch ON until an electrician verifies your overhead service mast is completely disconnected from the downed street wires:

• If your generator backfeeds power into a damaged meter box or snapped service drop lying in your yard, the utility pole transformer steps your generator's 240-volt output backward up to 7,200 or 13,800 volts, energizing the downed wire in your yard and electrocuting utility linemen or neighbors.
• If your house's service neutral or grounding electrode wire was ripped loose when the mast fell, running a generator bonded through the panel can energize your home's metal appliances and plumbing. Only run portable generators outdoors at least 6 meters (20 feet) from windows using heavy-duty extension cords plugged directly into individual appliances.

3. Underground service laterals, pad-mounted transformers, and energized ground faults¶

Even in modern neighborhoods with no overhead utility poles, severe electrical hazards occur when floodwaters, uprooted tree roots, or digging equipment breach an underground service lateral or a green steel pad-mounted transformer box on your front lawn:

• Never touch or sit on a green pad-mounted transformer cabinet: The green steel box in a residential yard steps 7,200- to 13,800-volt underground primary cables down to 120/240 volts. If a vehicle strikes the box, floodwater submerges it, or internal mineral oil overheats, stay at least 10 to 15 meters (35 to 50 feet) away and shuffle out of the area if the ground is wet.
• Melting snow circles and steaming soil: If an underground service cable shorts out beneath your lawn or driveway after tree root movement, the high-resistance earth fault heats the soil, causing a circular patch of snow to melt rapidly, steam to rise from the grass, or a distinct acrid smell of burning rubber insulation. Keep people and pets completely off that lawn section and call your electric utility immediately.

First aid and rescue rules if someone is shocked outside¶

If you look out your window or arrive home and see a person or pet lying unconscious near a downed wire, a metal fence, or a gutter downspout:

1. STOP and do not run over to grab them: If the person is lying on energized ground or still touching an energized chain-link fence, running up to touch them will immediately kill you via step potential or touch potential.
2. Call 911 / 112 / 999 immediately: Tell the dispatcher a person has been electrocuted by a downed utility line and the line is still live.
3. Only approach once utility crews confirm the grid is de-energized, or if the victim is clearly outside the high-voltage zone: Once the scene is confirmed electrically safe by emergency responders, check the victim for responsiveness and normal breathing. High-voltage alternating current causes immediate ventricular fibrillation (chaotic heart quivering) or respiratory paralysis. Begin Hands-Only CPR (100 to 120 chest compressions per minute, 5 to 6 centimeters / 2 to 2.4 inches deep) and apply an Automated External Defibrillator (AED) as soon as one is available.

Taking a hands-on first aid and CPR course from the Red Cross, St John Ambulance, or a local accredited provider prepares you to perform life-saving resuscitation and treat high-voltage entry and exit burns once emergency crews make the scene safe.

Frequently asked questions¶

Sources checked¶

• Occupational Safety and Health Administration (OSHA, United States): Downed Electrical Power Lines Fact Sheet, Step and Touch Potential Physics, and High-Voltage Clearance Standards.
• Federal Emergency Management Agency (FEMA / Ready.gov, United States): Power Outages and Downed Utility Line Safety After Severe Storms.
• Electrical Safety Foundation International (ESFI, United States): Downed Power Line Safety, Open Service Neutral Hazards, and Post-Storm Meter Base Inspection Guidelines.
• Health and Safety Executive (HSE, United Kingdom) and Energy Networks Association (ENA, United Kingdom): Avoidance of Danger from Overhead Electric Lines (GS6) and Public Emergency Guidance for Fallen Conductors.
• National Fire Protection Association (NFPA, United States): NFPA 70 National Electrical Code (NEC) Service Entrance Grounding Standards and Electrical Fire Response.

Related guides¶

• Downed power lines and vehicle electrocution
• Electric shock first aid and high-voltage safety
• Tree fallen on house or roof
• Electrical panel arcing and overheating
• Power outage preparation and safety
• Emergency numbers directory