Líne cumhachta tite ar do theach, díon, nó fál miotail¶

Nuair a bhuaileann stoirmeacha gaoithe tromchúiseacha, carnadh oighir, géaga crann ag titim, nó pléascanna claochladán sreang fóntais leictreach lastuas agus scaoileann sé ar dhíon do theach, gáitéir báistí, taobhlach alúmanaim, nó fál slabhra-naisc do chúlchlós, éiríonn do mhaoin láithreach mar chuid de chiorcad ardvoltais fuinnimh go talamh. Murab ionann agus sreangú tí faoi dhíon, a fheidhmíonn ag 120/240 volta (nó 230 volta san Eoraip) agus a thurais scoradán ciorcaid laistigh de na milleasoicindí de chiorcad gearr, iompraíonn línte fóntais lasnairde idir 240 volta (titim seirbhíse) agus 4,000 go 34,500 volta (fuathóirí dáileacháin príomhúla). Níos measa fós, tá scoradáin chiorcaid an fhostáisiúin áirgiúlachta (ar a dtugtar cuimsitheoirí uathoibríocha) cláraithe go sonrach chun líne laghdaithe a athfhuinneamh go huathoibríoch dhá nó ceithre huaire thar roinnt soicind nó nóiméad chun lochtanna soiléire brainse sealadacha crann a dhó.

Toisc go bhfuil ardfhriotaíocht leictreach ag shingles díon asfalt tirim, rachtaí adhmaid, ithir agus coincréit, is minic nach dtarraingíonn sreang dáileacháin phríomha 13,800 volta go ciúin ar do dhíon nó ar fhál an chúlchlós go leor locht reatha chun an fiús cuaille áirgiúlachta a shéideadh. Mar thoradh air sin, fanann an sreang fuinneamh go ciúin ag voltas marfach agus gáitéir báistí miotail a fhuinneamh, pluiméireacht copair, taobhlach alúmanaim, agus 100+ méadar (330+ troigh) de fhálú slabhra-nasc comharsanachta idirnasctha, agus fáinní comhlárnacha voltais (** poitéinseal céime**) á radú tríd an talamh mórthimpeall. Clúdaíonn an treoir chuimsitheach seo foscadh láithreach i gcoinne cinntí aslonnaithe, meicnic tine aischothaithe sreinge neodrach, marfacht fhéideartha tadhaill fál miotail, agus an teicníc aslonnaithe cos shuffling.

Do this now¶

Má tharraingíonn sreang áirgiúlachta lastuas, claochladán, nó crann braite seirbhíse scaoilte agus go dtiteann sé ar dhíon do theach, taobhlach, cabhsa, nó fál clóis, déan na sé chéim seo láithreach:

1. Bí beo agus marfach le gach sreang tite, fiú mura bhfuil sí spréach: Ná glac leis gur líne neamhdhíobhálach ghutháin, snáthoptaice nó teilifíse cábla í sreang íslithe, agus ná glac leis go bhfuil sreang leictreach chiúin marbh. Is féidir le reclosers fóntais uathoibríoch 13,800 volta surging ar ais isteach i sreang ciúin a sheoladh gan rabhadh.
2. Fan taobh istigh de do theach ach amháin má tá an struchtúr trí thine: Má tá líne chumhachta ina luí ar do dhíon, ar do phóirse nó ar do chabhsa agus nach bhfuil aon deatach nó tine istigh ann, ** fan istigh** amach ó na ballaí seachtracha. Nuair a shiúlann tú amach do dhoras tosaigh ar chéimeanna fliucha coincréite nó féar tais cuireann tú díreach laistigh den chrios grádán voltais talún agus faoi gháitéir báistí fuinnmhithe.
3. Cuir glaoch ar 911/112/999 AGUS seoladh éigeandála d’fhóntas leictreach láithreach: Cuir glaoch ar do cheantar áitiúil uimhreacha éigeandála (911 sna Stáit Aontaithe agus i gCeanada, 112 ar fud an Aontais Eorpaigh, 999 sa Ríocht Aontaithe) agus tuairisc "Tá líne chumhachta áirgiúlachta íslithe ag luí go díreach ar mo theach/fál." Díreach ina dhiaidh sin, cuir glaoch ar bheolíne briste éigeandála 24 uair an chloig d'fhóntas leictreach ionas gur féidir lena n-ionad rialaithe eangaí an líne friothálacha a dhífhuinneamh agus a chur i talamh.
4. NÁ déan teagmháil le do phríomh-phainéal scoradáin leictreach, do phluiméireachta nó do fhearais miotail má dhéantar damáiste don titim seirbhíse: Má thit príomhlíne ardvoltais ar do thitim seirbhíse tí ísealvoltais, nó má thit an sreang neodrach, is féidir do dhoras bosca scoradáin miotail, píopaí uisce copair, agus fearais talmhaithe a fhuinneamh ag na céadta nó na mílte volta. Fan go hiomlán ar shiúl ón bpainéal leictreach, doirtil, agus frámaí dorais miotail.
5. Fan ar a laghad 10 go 15 méadar (35 go ​​50 troigh) ar shiúl ó aon fhál, crann, nó lochán ag baint le líne downed: Má thiteann sreang trasna fál slabhra miotail, geata iarann ​​​​saoirsithe, fál beostoic sreinge, nó brainse crann fliuch, déantar fad leanúnach iomlán an chlaí sin a fhuinneamh ag voltas marfach, fiú trí theach síos an tsráid.
6. Má théann an díon trí thine agus go gcaithfidh tú aslonnú, suaitheadh ​​nó léimnigh leis an dá chos le chéile: Má chuireann deatach, stuanna scáineadh nó lasracha iachall ort an teach a aslonnú fad atá líne anuas ar an áitreabh, téigh amach trí dhoras ar an taobh thall den teach ón tsreang, ná déan teagmháil le ráillí miotail nó le doirse stoirme, agus ** Suaith do chosa le chéile gan iad a thógáil ** 1 méadar ar a laghad).

Crann cinntí oirbheartaíochta do líne chumhachta tite ar theach nó ar fhál¶

Bain úsáid as an gcrann cinntí oibríochta seo chun a chinneadh laistigh de shoicindí cé acu foscadh laistigh de do theach nó aslonnú grádán talún éigeandála a dhéanamh.

flowchart TD
    Start["Líne Fóntais Tite ar Dhíon Tí, Taobhlach, Crann nó Fál Clós"] --> Location{"1. Cá bhfuil tú anois?"}

    Location -->|"Amuigh sa chlós nó sa tsráid"| OutDist["Téigh ar ais láithreach go dtí 15 mhéadar (50 troigh) Glan Sreang, Fál agus Locháin"]
    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. Bonn méadair tarraingthe amach agus gáitéir báistí fuinnmhithe¶

Nuair a scairteann géag trom crann an cábla tríphléacs lastuas anuas, réabann sé an crann seoltán cruach scaoilte ó do sceimhleacha dín agus tarraingíonn sé an taobh amuigh bosca soicéad méadair leictrigh leathshlí de do thaobh.

• ** Taobhlach alúmanam fuinniúil agus gáitéir báistí**: De réir mar a bhíonn sreanga tarraingthe isteach na seirbhíse ag briseadh trasna imeall géar leatháin miotail an chinn aimsire, gealánacht díon miotail, nó gáitéir báistí alúmanaim, osclaíonn na slisní inslithe rubair dubh. Toisc go dtarlaíonn an locht seo ar thaobh na sráide áirgiúlachta (taobh na líne) de do phríomhphainéal scoradáin chiorcaid, ní féidir le príomhscorthóir 200-amp do theach ** turas chun stop a chur leis**.
• Cothaíonn an sreang lom 120/240-bholta na céadta amps go díreach isteach i do gháitéir báistí miotail, reanna anuas alúmanaim, agus taobhlach miotail. Críochnaíonn aon duine atá ina sheasamh ar thalamh fliuch taobh amuigh agus a dhéanann teagmháil leis an gob anuas nó an doras stoirme miotail an ciorcad go talamh agus déantar é a leictreamharú go marfach.

2. An ghuais "Seirbhís Oscailte Neodrach": cén fáth a dtéann píopaí agus ballaí pluiméireachta trí thine¶

I gcórais phas scoilte 120/240 volta Mheiriceá Thuaidh (agus go leor córas idirnáisiúnta talaimh TN-CS / PME), is é an cábla cruach lom airgid i do thiteann seirbhíse lastuas ná an rópa tacaíochta fisiceach agus an seoltóir fillte neodrach araon.

• Cad a tharlóidh má bhuaileann an tsreang neodrach lom fad is a fhanann an dá shreang te 120V dhubh ceangailte:
• Tarlaíonn luascáin fhiáin voltais ar an toirt ar fud asraonta do thí: titeann leath de d’asraonta 120 volta go 30 volta, agus ardaíonn an leath eile go 200 go 230 volta, rud a fhágann go bpléascann cosantóirí borrtha, oighinn micreathonnta, cláir foirnéise, agus stiallacha cumhachta agus pléascann siad lasracha laistigh de na seomraí.
• Sreabhann sruth fillte neamhchothromaithe trí do phíobáin uisce copair agus línte gáis: Agus an sreang neodrach lastuas briste, déanann gach sruth leictreach a fhilleann ó do theach iarracht bealach a aimsiú ar ais go dtí an claochladán cuaille tríd an domhan trí do shreang leictreoid talmhaithe ceangailte le do phíobáin uisce copair. Is féidir le do phíopaí pluiméireachta copair, stoic draein iarainn theilgthe, agus do chónaisc gháis cruach solúbtha róthéamh chuig teochtaí gealaí agus faucets cistine agus seomra folctha a leictriú.
• Sruth neodrach comharsana ag sileadh trí do phíobán uisce cathrach: Fiú má tá do scoradáin féin múchta, má dhéantar damáiste do shreang neodrach do chomharsa, is féidir leis an sruth fillte óna teach taisteal tríd an bpríomhphíobán uisce sráide miotalach roinnte isteach i do phluiméireacht íoslach. ** Ná déan teagmháil le píopaí uisce miotail, faucets laistigh, nó leis an bpríomhphainéal scoradáin leictreachais nuair a bhíonn sreanga seirbhíse síos.**

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.

Ceisteanna coitianta¶

Foinsí seiceáilte¶

• 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.

Treoracha gaolmhara¶

• Línte cumhachta laghdaithe agus leictriú feithicle
• Electric shock first aid and high-voltage safety
• Tree fallen on house or roof
• Painéal leictreach arcing agus róthéamh
• Power outage preparation and safety
• Emergency numbers directory