Power Surges can Damage Everything Electrical

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Home Pro Plumber provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  We are near near your home in Plano, TX; Allen, TX and Frisco, TX.  We service all homes in southern Collin County TX and Denton County, TX with no travel charges.

Call Home Pro Plumber today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.

Power Surges Have The Capacity To Damage Or Destroy 

Home Wiring, HVAC, Appliances, Electronics & Electrical Devices 

Lightning strike

Image Source: pixabay.com

Shown: Lighting Strike



Homes use 120-volt power — with voltage ranging from -169 volts (low) TO +169 volts (high).   A power surge spikes the voltage over 170 volts.   During a Power Surge, damage to; Home Wiring,  HVAC Systems, Appliances and Electronics can occur.

External Power Surges come into your home from the outside power line.   External Power surges can damage both your home’s wiring and every electrical device connected to it.

A Lightning Strike power surge is what most people think of causing a power surge.   This is one of the most damaging types of power surge.   There are over 20 million cloud-to-ground lightning strikes in the 48 contiguous U.S. states each year.    A power surge occurs if the voltage in the electricity rises above 170 volts.  A lightning bolt has 40,000 — 120,000 volts. *

In addition to lightening, there are many other ways power surges are created.  We will discuss some of the most common sources of power surges in this article. 

* Source: https://www.windpowerengineering.com/business-news-projects/how-much-power-in-a-bolt-of-lightning/



A Power Surge can be created any place in the power grid from the power plant to the neighborhood transformer near your home.   Just below we detail the individual components of the U.S. Power Grid,  We describe what each component does, how they are interconnected, and how they relate to each other during the creation and transmission of electricity from Power Plant to your home.

1. Electricity is generated in the power plant.  There are typically multiple generators that produce electricity within each power plant.

In Most Power Plants:

  • A fuel is used to heat water until it’s steam.  (It can also be moving water in a hydroelectric plant).
  • The steam turns the blades of the generator’s turbine.
  • The turbine provides the power to spin the generator.
  • Once the steam has been used to spin the turbine, the steam is cooled back into water inside a cooling tower (see a cooling tower in 2nd pic  below).
  • Once the cooling tower cools the steam back into water,  the water is returned and  reheated until it’s steam again.

power plant electricity generator

Shown: Electricity Generator Inside A Power Plant

Image Source: ShutterStock

One typical power plant generator produces 345,000 volts, and can produce as much as 765,000 volts.   Power plants step up the electricity’s voltage before it leaves the power plant.  This is because less electricity is lost (while in the power lines) when the voltage is high.

electricity generating power plant

Shown: Power Plant (in background).  Cooling Tower (in Foreground).

Image Source: Pixabay

2. Electricity Transmission Lines carry electricity long distances.  They are huge lines connected to tall towers.  The lines are also interconnected.  If one line fails, another transmission takes over the failed line’s load.  Transmission lines deliver electricity to electrical sub stations.

large power transmission lines on power towers

Shown: Power Transmission Lines On Tall Towers

Image by Nicole Köhler from Pixabay


3. Electrical Substations use step-down transformers to reduce the voltage to 12,000 volts.  Substations are small, fenced in areas that contain switches, transformers, and other electrical equipment.

electricity substation

Shown: Electrical Substation

Image by Michael Gaida from Pixabay


4. Upon leaving the substation, the electricity enters the Power Distribution lines.  These can be overhead or underground.  Overhead distribution lines are often seen along busy streets.  In areas developed after 1960, residential areas are typically served by underground distribution lines that bring the electricity to your home.

local overhead power transmission lines

Shown: Electricity Distribution Lines

Image by René Schué from Pixabay


5. Before electricity enters your house, the voltage is reduced again by a (step down) Transformer.  These are the round gray cans on power poles OR a box (typically painted green) that sits on the ground (in areas with underground electricity distribution lines).

The neighborhood transformer reduces the electricity voltage to 120 and 240 volts.  120 voltage runs small electricity users, such as a refrigerator, computer, or a portable electric heater.  240 voltage is for large users of electricity such as; central air conditioning, a large window air conditioner, electric clothes dryer, electric kitchen range / cooktop / wall oven, and electric furnaces.


electricity transformer on pole

Shown: Electricity Transformer For Overhead Power Transmission Lines

Image by Nature Blossom from Pixabay


electricity transformer for underground utilities

Shown: Electricity Transformer For Under Ground Power Transmission Lines

Image by Vince Alvino from Pixabay


6. Once the local transformer steps the voltage down to 120 or 240 volts, it comes into your home and is ready to use.

photo of electrical outlet

Shown: 120 Volt Electrical Outlet

Image Source: ShutterStock

240 volt electrical outlet

Shown: 240 Volt Electrical Outlet

Image Source: ShutterStock




Once common source of power surges occurs during increasing electricity demand.   Adding additional power generators or additional power plants causes more electricity to flow into the lines and can create a line voltage surge.

Problems with electrical distribution equipment, such as overheated transformers or broken power lines that fail and stop carrying electricity can also cause power surges. These kinds of surges are impossible to predict.  When an electrical line fails, the electricity it was carrying can create a brief power surge in nearby electrical lines.

A Short Circuit Within The Electricity Distribution Network is another common cause of a power surge. A short circuit is defined as electricity taking a different path than the correct path.   If an electrical path with less resistance (than the correct path) occurs, electricity will flow through that path instead because shorter paths have less resistance.  This is what the term “short circuit” means.

A Common Short Circuit Is Occurs When Tree Limbs touch power distribution wires.  If the power wire touches a tree, the tree provides a direct path for electricity to flow into the ground (the earth).  This is why you see trees trimmed away from power lines.

photo of tree trimmed away from electrical distribution lines

Image Source: Photo by Ibrahim Boran from Pexels

Shown: Tree On Left Trimmed Away From Electrical Line


Click In The White Arrow (In Center Of Image Below) To See What Happens When A Tree Touches A Power Line And A Short Circuit Occurs

Power Blinks Occur Because:

  • Something goes wrong within the power distribution network.
  • A protective device reacted to the problem and disconnected the affected power line(s).
  • If a Fuse exists in the affected power line, the fuse blows and must be replaced by power-restoration crews.
  • If a Circuit breaker exists in the power line, it will retest the line to check if the problem has cleared.  It will reconnect the line and disconnect again if the problem still exists.  It may do this several times.  If the short-circuit continues, the breaker will shut off until power-restoration crews correct the problem.  During the testing by the circuit-breaker, power surges can repeatedly come into your home.
  • When a default causes a power line to disconnect, the electricity flowing through that line briefly reroutes to nearby lines, until the ground wire(s) carry the excess electricity away.  During the reroute, the power in your home may blink.


Surge Protectors Stop Power Surges From Getting To Your Devices 

A Power Surge Occurs When A Power Outage Is Restored 

At one moment power line is carrying no electricity due to a power outage.   When power is restored, a surge of electricity races into and through the line.

photo of circuit breaker panel

Shown: Circuit Breakers Panel

Image Source: CanStockPhoto

The Best Way To Protect Your Home And Contents From The Power Surge That Occurs After A Power Outage

Is To Turn Off The Main Breaker In Your Home’s Circuit Breaker Panel.

Wait 5 minutes after power is restored before turning the Main Breaker back on.



Whole House Surge Protectors can protect your home’s electrical wiring + every electrical device from damage caused by an EXTERNAL Power Surge.


A Comprehensive Power Surge Protection Strategy Incorporates:

First-Tier Surge Protection at the power meter. — This is called a TYPE 1 Surge Protector.

Second-Tier Surge Protection at the circuit breaker panel. —  This is called a TYPE 2 Surge Protector.

Third-Tier Surge Protection where devices plug into an outlet. — This is called TYPE 3 Plug-In Surge Protector.  These protectors are for internal power surges. 

Shown: Electric Meter-Socket Surge Arrestor

Image Source: Amazon Embedded Link

NOTE: Dangerous Levels Of Electricity Exist At The Electric Meter & Inside Circuit Breaker Panels.

NOTE: First-Tier & Second Tier Surge Protection Devices Must Be Installed By A Licensed Electrician.

The arrestor shown sits between the electric meter and the house.   It stops External Power Surges before they can enter the circuit breaker panel.    The manufacturer of the unit shown states that it provides protection of up to 50,000 peak Amps of surge.  A Whole-House surge protector guards the home’s wiring + all electrical devices from a power surge (up to the capacity of the protector).

Copy The Link Below Into Your Browser To Read Details On The Electric Meter-Socket Surge Arrestor Shown Above:


** NOTE: The Surge Protector shown above is rated at 50,000 amps.   This Old House says “whole-house systems should be rated to stop a 40,000-amp surge, at minimum”.  **

Click Here To See A Meter-Socket Surge Arrestor Installed:  Meter-Socket Surge Arrestor Installed


Shown below is a modestly priced, Whole House, Surge Protector that installs inside the Circuit Breaker Panel.   Near its top is the location of the indicator light that glows green indicating the protector is working properly.  **

** NOTE: This Surge Protector is rated at 20,000 amps.   This Old House says “whole-house systems should be rated to stop a 40,000-amp surge, at minimum”.  **

**Source: https://www.thisoldhouse.com/ideas/surge-protection


Whole Home Surge Protective Devices are for higher-level External power surges.  External surges are to large to be stopped by plug-in power surge protectors.   Whole House SPD’s provide surge suppression for items that can’t be plugged into plug-in surge protectors, such as HVAC, electric dryer, electric stove / cooktop / wall oven, and lighting.  Surge Protectors redirect excess current safely to ground (earth).  This reroutes the surge before it has the chance to enter your homes wiring.


 SHOWN: General Electric Model THQLSURGE. 

Click On Photo To: View, See Details, or Purchase This Item From Amazon.com


Note: We Not Sell Or Install Whole House Surge Protectors.




Internal Power Surges

Up to 3/4 of power surges come from inside the home.   Internal Power Surges occur several times each day when high electricity-demand devices turn off.   Hair dryers, electric portable heaters, and window air conditioners are three of the biggest creators of internal power surges.  Since heaters and a/c are controlled by a thermostat, they can cycle on & off many times in a single day.  Power surges may also created by older refrigerators and freezers.

If you have seen a light bulb get brighter for a moment, you have witnessed a power surge.  When a high-demand electrical device (such as a portable electric heater) shuts off, there is a brief surplus of electricity in the homes electrical wiring.  The excess electricity moves into the ground wire, which takes it back to the circuit breaker panel and then into the earth.  All this happens very fast, as the electrical wiring is designed to carry excess electricity away.

During that brief moment when excess electricity exists in the home’s electrical wiring, a power surge occurs to every outlet on that circuit (and possibly into other circuits).  Today’s HVAC Systems and appliances have sensitive electronics just like computers do.  These appliances are subject to tiny amounts of damage each time an internal power surge occurs.  Over time, repeated internal power surges shorten the life of electronics & appliances.


Click On The White Arrow (in the center of the image) Below To See A Video About A Washer Damaged By A Power Surge: Washer Damaged By Power Surge


Guarding Against All Power Surges Requires Two Levels Of Defense:

  • A Whole-House Surge Suppressor(s) — to stop external power spikes.
  • Individual “Plug-In” Surge Suppressors — to stop small, internal power surges.

Without surge protectors, the only way to protect your: HVAC System, Appliances & Electronics is to disconnect power to them.  This is most easily accomplished by turning the circuit breaker off.  The problem is, power surges cannot be predicted.  Other than disconnecting power, the only way to protect your home’s expensive electronics is to have power surge protectors operating 24/7.

Plug-In Surge Protectors For Internal Power Surges 

3/4 of power surges originate inside the home, they are called Internal Power Surges.   The Whole-House Surge Protector does not protect your home from surges originating inside the home.

Using Plug-In Surge Protector will guard sensitive appliances and electrical devices from internal power surges.   Any device with a digital readout has electronics inside.  Today’s appliances typically have sensitive electronics too.  If you are in doubt whether an appliance or device needs a surge protector, add one to be sure.

All plug-in surge protectors stop the power surge itself.  Additionally, some surge protectors will block the electricity from going past them until the current is stabilized.  This style of surge protector will light up to let you know it has power, but will delay allowing electricity through the surge protector until the surge protector is satisfied with the stability of incoming current.

Some brands of surge protectors have an “Delay” Indicator.  We show once such brand below.  This indicator light is typically yellow, and is lighted while the surge protector monitors the electrical current for stability.   Other brands may delay the power, but not indicate that.  Check your owner’s manual to how to know if a surge protector has a delay mode, and when it is in delay mode.

Shown: Surge Protector With Delay Light.   Products shown do not constitute endorsements by Al’s Plumbing, Heating & A/C.


SHOWN: Tripp Lite Model TLP1008TE:

Click On Photo To: View Item, See Details, or Purchase From Amazon.com

How Does A Plug In Surge Protector Work?   When electrical voltage rises above a safe level, the surge protector has internal components (called varistors) that absorb the excess voltage and divert it to the Surge Protector’s ground wire.  The home’s wiring then carries the excess voltage away.  This prevents a power surge from from reaching the devices plugged into the surge protector.

Note: Plug In Power Surge protectors Do Not Have The Capacity To Protect Against External Power Surges.  The plug in devices are designed to protect against small, internal surges.


One of the biggest concerns with Plug In surge protectors is if they disconnect power (to the items plugged into them) if they become compromised.  The only way to be sure is to read the marketing verbiage provided.  If they don’t say they disconnect power, the safest route is to assume they don’t.

Tripp Lite Is A Brand Of Plug In Power Surge Protector That Disconnects Power When Compromised.  This brand also comes with insurance to replace protected items if the Trip Lite power surge protector fails to protect them.   This verbiage came from Tripp Lite’s website (www.tripplite.com) under the heading “Premium Safety Features”.  “Automatic shut off cuts power to all outlets when protection has been compromised.”   Tripp Lite Sells Surge Protectors In A Multitude  Of Different Configurations, From 1 Outlet To Serving Many Devices.

Note:  Al’s does not endorse any brand of Surge Protectors only because we don’t have first-hand knowledge of all devices.  There may be other brands that also disconnect power.


Power Surges Often Damage HVAC System Components

As shown in the video within this article, power surges can damage HVAC Systems.   A central a/c or furnace often stops running after a large power surge.  The two most common surges that damage HVAC are lightning strikes or when electricity is restored after an outage.

If the surge is large (like lighting or a short-circuit in the electricity distribution system) — there are other components that are subject to failure in addition to the outside a/c unit or furnace control board.  If the power surge is quite large the cost to repair the a/c outside unit may not be justified unless it’s nearly new.  In that case, the system must be replaced.



  • Damaged Control Board:  The control board is the “brain” for the outdoor unit + there is a second control board in the furnace.  Control boards tell the outside unit or furnace which functions to perform, and in what order.  Being a sensitive electronic control-board, it is highly subject to damage from a power surge / spike.

Image Source: Amazon embedded link

SHOWN: HVAC System Control Board.  There is a specific unit required for each: brand, model and size HVAC System.

  • Damaged Capacitor:   Capacitors are a battery that sends a extra jolt of electricity to start a motor running.  There is typically one for the outside unit’s fan and another for the outside unit’s compressor.  Another once exists inside the furnace to start the blower motor.
  • Electrical components that use large amounts of electricity typically need an extra jolt of electricity to start running. Capacitors are the battery that provides the jolt.  In a central air conditioner, capacitors serve: the outside unit compressor, the outside unit fan, & the furnace blower fan.
  • A capacitor is the most common air conditioning part to fail due to a power surge, as a relatively weak power surge can damage a capacitor.   Over time a damaged capacitor can damage the a/c’s compressor, as the compressor depends on the extra jolt of electricity from the capacitor to start running.   If the compressor does not get that jolt, it may start running anyway.  But without the capacitor, the start is extremely hard on the compressor.  “Hard starting” is when an AC struggles to turn on and then shuts off in a short time.   A compressor can fail due to damage from hard starting.

Image Source: Amazon embedded link

SHOWN: HVAC System Capacitor.   There is a specific unit required for each: brand, model and size HVAC System.


  • Damaged Contactor Relay Switch:  This is a low-voltage switch controlled that is controlled by the thermostat inside the house.  This low-voltage relay then operates the high-voltage relay switches for the: outside unit compressor, the outside unit fan, & the furnace blower fan.  The high-voltage relays turn on 120V electrical power (to fans) or 240V electrical power to the compressor in the outdoor unit.


Image Source: Amazon embedded link

SHOWN: Contact Relay Switch.  There is a specific unit required for each: brand, model and size HVAC System.

  • Damaged Compressor:  The compressor moves the refrigerant though the outside unit & the cooling-coil inside the furnace or duct work.   Being an electrical device with a lot of wiring, the compressor can be damaged by a large power surge.   A small power surge that damages a capacitor can also damage a compressor over time
  • The cost to replace a central a/c compressor typically exceeds the value of the outdoor unit unless it’s quite new.   In most cases, the outdoor unit must be replaced if the compressor is damaged due to a power surge.   When looking inside the outdoor unit, the largest component is the compressor.

There are many HVAC components that can be damaged by a power surge.   In summer, a power surge can damage the control board in the outside unit + the furnace’s board if the central a/c is running at the time of the surge.   A surge caused by a restoration of electricity can damage HVAC — if the thermostat setting is calling for cooling when the power is restored.  The HVAC System will start up the moment power is available, and that could be accompanied by the power surge.


Symptoms Of A Central A/C That Is Not Working Correctly

These symptoms tell you something is wrong with your central a/c — regardless of what caused the problem:

  • Nothing working (thermostat turned off, failed thermostat).
  • Outside unit suddenly not running  (tripped circuit breaker, thermostat changed from “cooling”).
  • Tripping Circuit Breaker.  A/C starts tripping the circuit breaker (overloading the circuit due to malfunction in HVAC system).
  • Furnace blower suddenly not running (tripped circuit beaker — furnace on separate breaker as outside unit, thermostat changed from “cooling”).
  • Fan is in the outside unit is not running (capacitor has failed, relay switch has failed, other).
  • Air coming from the outside unit is not warm (compressor not running).
  • No air coming from the ducts (furnace blower fan not running, cooling coil inside furnace has iced up due to low refrigerant or failed control switches).
  • Less air coming from ducts than in the past (dirty air filter needs replaced, dirty cooling-coil — above or inside the furnace).
  • Output air not as cool as in the past (low refrigerant and / or dirty outside unit).
  • Refrigerant just recharged, now blowing much colder than in the past (refrigerant overcharged — to much refrigerant).
  • Warm air blowing inside (compressor not running).
  • Outside unit is making new noises you have not heard before.
  • Outside unit shakes when it turns on (compressor is likely hard starting).
  • Ice is forming on the outside a/c unit (low refrigerant or failed control switches).
  • “Burned” smell (wiring is burning out).
  • A/C is running constantly during extremely hot weather.  This may not be a problem — the system is trying to keep up.
  • A/C is running constantly during only warm weather (low refrigerant, dirty outside unit, dirty air filter).
  • Electricity bill has spiked upward (low refrigerant, dirty outside unit, dirty air filter).

Note: Frost will form on the outside unit of a Heat Pump in winter.  It will defrost itself as needed.

Catch HVAC System Problems Before The System Stops Working

Due to its complexity, there are many things that can go wrong with a central a/c system.  The Best Defense Is An Annual Maintenance & Cleaning Of components (as needed).   The system will be checked for refrigerant level and components that have failed, or are near failing.   The system’s operation will be tested to ensure it is working at its maximum cooling ability and energy efficiency.

Your a/c is most likely to stop working when you need it most (because that’s when it is running the most).  A failing component (such as a capacitor) may be able to function when the a/c is not cycling a lot, but then fails when heavy demand is placed on it during hot DFW summers.

Discovering upcoming problems will save: being miserable with heat, being inconvenienced, and possibly after-hours repair charges (they are often higher than during normal office hours).   It may also catch the need for an inexpensive repair (such as capacitor) from causing very expensive repairs (such as a burned out compressor due to failed capacitor).


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Home Pro Plumber provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  We are near near your home in Richardson, TX; Garland, TX;and northeastern Dallas, TX.  We service all homes in southern Collin County TX and Denton County, TX with no travel charges.

Call Home Pro Plumber today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.