Ua hāʻule ka laina mana ma kou hale, ka hale, a i ʻole ka pā metala¶

I ka wā o ka makani ʻino, ka hōʻiliʻili hau, ka hāʻule ʻana o nā lālā lāʻau, a i ʻole ka pahū ʻana o ka mea hoʻololi e hoʻopaʻa i kahi uwea pono uila ma luna a hāʻule i luna o kou hale, nā ʻauwaha ua, ka ʻaoʻao alumini, a i ʻole ka pā kaulahao hope, e lilo koke kāu waiwai i ʻāpana o kahi kaapuni kiʻekiʻe kiʻekiʻe i ka honua. ʻAʻole like me nā uwila hale i loko, e hana ana ma 120/240 volts (a i ʻole 230 volts ma ʻEulopa) a hele i kahi mea hoʻomaha kaapuni i loko o nā milliseconds o kahi kaapuni pōkole, lawe ʻia nā laina pono ma waena o 240 volts (lawelawe lawelawe) a me 4,000 a i 34,500 volts (nā mea hānai hoʻolaha mua). ʻO ka mea ʻoi aku ka ʻino, ua hoʻonohonoho pono ʻia nā mea hoʻokaʻawale kaʻa kaʻa (i kapa ʻia ʻo reclosers aunoa) e hoʻomaʻamaʻa hou i kahi laina i hoʻohaʻahaʻa ʻia ʻelua a ʻehā manawa i loko o kekahi mau kekona a i ʻole mau minuke e hoʻopau i nā hala o nā lālā lāʻau.

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.

E hana i kēia i kēia manawa¶

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 helu pilikia (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]

No ke aha e hiki ai i kahi laina mana i hoʻohaʻahaʻa ʻia ma kou hale ke puhi i nā paia i ke ahi mai loko¶

Ke hāʻule ka lālā lāʻau ma luna o ka triplex service drop e holo ana ma waena o ka pou alanui a me ke kila o kou hale weatherhead mast, hiki i ʻekolu mau hewa uwila pōʻino i ka manawa hoʻokahi i loko o ka hale o kou hale:

1. Huki ʻia ke kumu mika a me nā ʻauwai ua ikaika¶

Ke huki ka lālā lāʻau kaumaha i ke kaula triplex ma luna o ke poʻo i lalo, ʻokiʻoki ia i ke kia o ke ala hao kila mai nā hale o kou hale a huki i ka ** pahu kumu mika uila** ma waho o kou ʻaoʻao.

• E hoʻoikaika ana i ka ʻaoʻao alumini a me nā ʻauwaha ua: I ka wā e ʻoki ai nā uwea i huki ʻia ma ka ʻaoʻao o ka ʻaoʻao metala ʻoi o ke poʻo o ka makani, ka ʻālohilohi o ka hale metala, a i ʻole ka ʻauwai ua alumini, ua wehe nā ʻāpana ʻeleʻele ʻeleʻele. No ka mea aia kēia hewa ma ka ʻaoʻao alanui pono (ʻaoʻao laina) o kāu papa hoʻomaha kaapuni nui, ʻaʻole hiki i ka mea haʻihaʻi nui 200-amp o kou hale ʻaʻole hiki ke holo e hoʻōki.
• ʻO ka uea 120/240-volt wale nō e hānai pono i nā haneli amps i loko o kāu mau ʻauʻau ua metala, nā alumini alumini, a me nā ʻaoʻao metala. ʻO kēlā me kēia mea e kū ana ma ka ʻāina pulu ma waho e hoʻopā i ka puka i lalo a i ʻole ka puka ʻino metala e hoʻopau i ke kaapuni i ka honua a make i ka uila.

2. ʻO ka pilikia "Open Service Neutral": no ke aha e wela ai nā paipu paipu a me nā paia¶

Ma ʻAmelika ʻĀkau 120/240-volt ʻōnaehana māhele (a me nā ʻōnaehana hoʻokumu honua TN-C-S / PME he nui), ʻo ke kaula kila kala ʻole i kāu hāʻule lawelawe ma luna ʻo ia ka ke kaula kākoʻo kino a me ka ** alakaʻi hoʻihoʻi ʻole **.

• He aha ka hopena inā paʻa ka uea kū ʻole i ka wā e pili ana nā uea wela 120V ʻeleʻele ʻelua:
• Hiki koke mai nā ʻōniu uila ʻāhiu ma waena o nā puka puka o kou hale: hāʻule ka hapalua o kāu puka puka 120-volt i 30 volts, a ʻo ka hapa ʻē aʻe e piʻi i 200 a 230 volts, e hoʻoulu ai i nā pale pale, nā umu microwave, nā papa umu ahi, a me nā kaula mana e pahū a ʻā i loko o nā lumi.
• Ke kahe nei ke au o ka hoʻihoʻi ʻole i kou mau paipu wai keleawe a me nā laina kinoea: Me ka haki ʻana o ka uwea kūʻokoʻa ma luna o ke poʻo, e hoʻāʻo ana ke au uila a pau e hoʻi mai ana mai kou hale mai e ʻimi i ke ala e hoʻi ai i ka transformer pole ma o ka honua ma o kāu ** uwea electrode kumu i hoʻopili ʻia i kāu paipu wai keleawe**. Hiki i kāu mau paipu paipu keleawe, nā ʻauʻau hoʻoheheʻe hao, a me nā mea hoʻohui kinoea kila maʻalahi hiki ke wela i nā mahana ʻālohilohi a hoʻoheheʻe i nā kīʻaha kīʻaha a me ka lumi kaukau.
• Ke kahe kūʻokoʻa o nā hoalauna e kahe ana ma kāu paipu wai kūloko: ʻOiai ua pio kāu mau mea haki, inā ua poino ka uea kuʻuna o kou hoalauna, hiki ke hoʻihoʻi i ke au mai ko lākou hale ma ke ala nui o ke alanui metala i loko o kou paipu lalo. Mai hoopa aku i na paipu wai metala, na paipu o loko, a i ole i ka papa wawahi uwila nui ke pau na uwea lawelawe.

3. Hoʻopili keʻa mua a i ke kula kiʻekiʻe.¶

Inā paʻi ka uea mua 7,200-volt a i ʻole 13,800-volt ma luna o ka pou alanui a hāʻule i lalo o nā uea lawelawe lua 120/240-volt haʻahaʻa e hānai ana i kou hale, ** mau tausani volts** e piʻi pololei i lalo i kāu kia lawelawe i loko o kāu papa haʻihaʻi nui. Hoʻoholo wale ʻia nā mea hoʻopau kaapuni hale e hoʻopau i 240 volts; Lele pololei ʻo 7,200 volts ma luna o kahi ʻāpana "OFF" i loko o kahi arc plasma mau, e puhi ana i nā pale puka puka mai nā paia o ke keʻena moe a me ka hoʻā ʻana i nā kumu lāʻau i loko o nā lua o ka pā.

ʻO ka pā uila metala: no ke aha e hana ai nā kaulahao a me nā pā uea no nā poloka¶

ʻO kekahi o nā hiʻohiʻona make loa ma hope o ka makani ʻino, ʻino, a i ʻole ʻino hau, ʻo ia ka laina mana i hoʻohaʻahaʻa ʻia e kau ana ma luna o ka pa kaulahao hope, pā hao-hao, a i ʻole pā uea / uea ulana mahiai.

1. No ke aha i paʻa ʻole ai ka pā i ka laina mana¶

Manaʻo maoli ka poʻe nona ka hale ma muli o ka hoʻonoho ʻia ʻana o nā pou pā kaulahao kila i loko o ka lepo i kēlā me kēia 2.4 a 3 mau mika (8 a 10 kapuaʻi), ʻo ka laina uila e hāʻule ana ma ka pā e pōkole koke i ka lepo a hoʻokuʻu i ka mea haʻihaʻi. ʻOiaʻiʻo:

• He kiʻekiʻe ke kūpaʻa uila o nā paepae pou paʻa a me ka lepo maloʻo a one paha (pinepine 50 a 500 ohms no kēlā me kēia pou).
• ʻO ka laina 7,200-volt e kau ana ma luna o ke kaʻa kaʻa kaʻa kaulahao ma luna o ka 15 a i ka 40 amps i loko o ka lepo, ma lalo loa o ka paepae 100 a 400-amp i koi ʻia no ka holo ʻana i kahi mea hoʻoheheʻe mea hoʻohana.
• 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. E koho i ka puka puka ma ka ʻaoʻao o ka hale KUE i ka uwea hāʻule: E nānā i nā puka makani ma mua o ka wehe ʻana i kekahi puka. Mai puka i waho ma lalo o ka eave o ka hale kahi e kau ai ka uea, a pale i nā ala kaʻa a i ʻole nā ​​​​patio e hoʻopā ana i ke kumu.
2. E nānā i ka pā puka a pale aku i ka hoʻopā ʻana i nā ʻāpana metala: Inā he puka lāʻau a i ʻole ka puka fiberglass e alakaʻi ana i ka lānai lāʻau maloʻo a i ʻole ka ʻanuʻu paʻa ma ka ʻaoʻao lōʻihi o ka hale, e wehe i ka puka me ka hoʻohana ʻana i ka lima o loko wale nō. Mai lalau i ka puka puka aluminika, pale metala puka puka, a i ole ka lima lanai metala.
3. E lele i waho o ka paepae puka me nā wāwae ʻelua: Inā manaʻo ʻoe ua ikaika ka ʻaoʻao o ka hale, ka paepae metala a i ʻole ka lānai, mai hele i waho me ka wāwae hoʻokahi i loko o ka hale a hoʻokahi kapuaʻi ma ka honua i waho (ʻo ia ke alahaka i ka mana uila o ka hale i ka honua). E kū ma ka papahele o loko, e hoʻopaʻa i kou mau lima ma kou umauma, a hopu me nā wāwae ʻelua i paʻa pono i pae ʻoe i ka honua ma waho me nā wāwae ʻelua i ka manawa like me ka hoʻopā ʻole ʻana i ka pā.
4. E hoʻokō i ka shuffle ʻelua kapuaʻi i 15 mika (50 kapuaʻi):
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. ʻO kahi ʻē aʻe, hop e like me ka puali me nā wāwae ʻelua i hoʻopaʻa paʻa ʻia no laila hoʻokahi wale nō wahi e pili ana i ka honua i kēlā me kēia manawa.
8. E hoʻomau i ka wili a i ʻole ka lele ʻana a hiki i ka ** ma kahi o 15 mika (50 kapuaʻi) ka mamao** mai ka hale, ka uwea i hoʻohaʻahaʻa ʻia, nā pā metala, a me nā lepo pulu.

ʻO nā panela lā, nā mea hana hoʻihoʻi, a me ka hoʻopili hou ʻana i ka uila ma hope o ka ʻino¶

Ma mua o ka hoʻihoʻi ʻia ʻana o ka mana ma hope o ka hāʻule ʻana o kahi laina pono ma kou hale, pono e hoʻokele ʻia ʻelua mau pōʻino uila: ** nā pūʻulu kiʻi kiʻi solar (PV) ma luna o ka hale** a me ** nā mea hana hoʻihoʻi portable **.

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. E hoʻokokoke wale aku i ka manawa e hōʻoia ai ka poʻe lawelawe pono ua pau ka ikaika, a i ʻole inā maopopo ka mea i hoʻopaʻa ʻia ma waho o ke kaona uila kiʻekiʻe: Ke hoʻopaʻa ʻia ka mea i hoʻopaʻa ʻia i ka uila e nā mea pane ulia pōpilikia, e nānā i ka mea i hōʻeha ʻia no ka pane ʻana a me ka hanu maʻamau. ʻO ka ʻāwili ʻana o ka uila kiʻekiʻe ke kumu i ka ventricular fibrillation (ke haʻalulu puʻuwai) a i ʻole ka maʻi hanu. E hoʻomaka i ka CPR lima wale nō (100 a i 120 mau hoʻopaʻa umauma i kēlā me kēia minuke, 5 a 6 kenimika / 2 a 2.4 iniha ka hohonu) a hoʻopili i kahi Automated External Defibrillator (AED) i ka wā e loaʻa ai kekahi.

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.

Nā alakaʻi pili¶

• Downed power lines and vehicle electrocution
• Electric shock first aid and high-voltage safety
• Tree fallen on house or roof
• Pākuʻi uila a me ka wela nui
• Power outage preparation and safety
• Emergency numbers directory