US electrical power dangers

Any form of energy, when not properly controlled or harnessed, can result in serious danger to those who use it. Electricity at any voltage can be dangerous and should always be approached with caution. Direct Dangers of Electricity include a variety of hazards that include Electric Shock, Physical Burns, Neurological Damage and Ventricular fibrillation resulting in death. The indirect dangers of electricity include for example fall due electric shock, an explosion, or a fire.

Electric Current affects the body when it flows through. Human can feel around about 1 milliampere (mA). The current may cause tissue damage or heart fibrillation if it is sufficiently high. 10-20 mA is beginning of sustained muscular contraction (“Can’t let go” current) and 30 mA can cause the onset of potentially fatal respiratory paralysis. A low-voltage (110 to 220 V), 50 or 60-Hz AC current travelling through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60mA.

The National Fire Protection Association notes that faulty or damaged wiring and related electrical equipment cause 69 percent of electrical fires, followed by lamps, light fixtures, cords, plugs, transformers and other power supplies.

Today’s U.S. electricity system is a complex network of power plants, transmission and distribution wires, and end-users of electricity.
Electrical safety is the leading subject in the North American power industry, but at home people in USA are stuck with a 100+ year old plug design that is far behind other countries in terms of safety features.

ARE AMERICAN PLUG SOCKETS DANGEROUS? video gives some observations about the differences between the UK and US electrics and fire safety:

“Each year, approximately 2,400 children suffer severe shock and burns when they stick items into the slots of electrical receptacles. It is estimated that there are six to 12 child fatalities a year related to this.”
I guess that data makes me wonder about those who say they are safe.

Perhaps the weakest link in the US electrical system video gives on overview of dangers of electrical outlets and extension cords.

Most of North America (and Central America, and some of South America) use connectors standardized by the National Electrical Manufacturers Association. Those connectors are called NEMA connectors.

NEMA 1-15 ungrounded (Type A) plugs have two parallel blades and are rated 15 A at 125 volts. They provide no ground connection but will fit a grounding NEMA 5-15 receptacle. Ungrounded NEMA-1 outlets are not permitted in new construction in the United States and Canada, but can still be found in older buildings. You can shock yourself with many USA NEMA connectors if you just slipped around the end at the wrong moment. That is the original plug from the very early 20th century… It couldn’t be changed later because there were too many NEMA-1 outlets in service.

NEMA 5-15 grounded (Type B) plug has two flat parallel blades like NEMA 1-15, and a ground (earth) pin. It is rated 15 A at 125 volts. The National Electrical Contractors Association’s National Electrical Installation Standards (NECA 130-2010) recommends that sockets are mounted with the ground hole up so that a falling object makes first contact with the ground pin. This socket is recommended in IEC standard 60906-2 for 120-volt 60 Hz installations. NEMA 5-15 grounded (Type B) sockets accepts also NEMA 1-15 ungrounded (Type A) plugs. In stage lighting, this connector is sometimes known as PBG for Parallel Blade with Ground, Edison or Hubbell. “Typical” 120v receptacles are protected with 15A breaker. This protects the outlet against overload.


Starting with the 2008 Edition of the NEC (National Electrical Code) the NEC has required tamper-resistant receptacles be used in certain locations. The NEC has been increasing the requirement for receptacles to be tamper-resistant with the revisions after that.
Tamper-resistant receptacles work by having a plastic shutter in front of where the plug gets inserted, which is only moved out of place if objects are placed into both slots of the receptacle
TR-rated outlets feature “TR” engraved into the outlet faceplate, typically between the two prongs. The shutters remain closed until the proper plug is inserted. This ensures that items like knives, forks, or loose jewelry are not able to access plugs, thus reducing electrical shock injury.

Nothing is safe. There are only degrees of safety. None of these designs can always prevent a determined or negligent person from electrocuting themselves.


There are some people that think that TR Tamper Resistant Outlets Suck

There are also higher current than 15A outputs in use in USA, but a general-use receptacle cannot be on any circuit larger than 20 amps. The NEMA 5-20 AP variant has blades perpendicular to each other. The receptacle has a T-slot for the neutral blade which accepts either 15 A parallel-blade plugs or 20 A plugs. The NEMA 5-20 AP wall socket can accept both 20A plug and 15A plug.

While normal electrical outlets in USA output 120V AC, that’s not the whole story and the voltage the power distribution to most houses work. The distribution voltage is normally the sum of the two 120V lines that are are at opposite phase (180 degree phase shift) plus neutral wire. But in some cases power can come from two 120V lines that have 120 degrees phase shift (some locations which use certain type of three phase power feed). Learn about the US electrical system in this The US electrical system is not 120V video:

US electrical system uses circuit breakers as wiring and fire protection. Circuit breakers are there to stop the cable in the walls of your house melting and possibly catching fire – circuit breakers and fuses perform the function of stopping a fire (which of course is also very dangerous to life). Standard circuit breakers shut off power when the current is too high, like 10, 15, or 20 amps, but a mere 0.030 amps through a body can cause paralysis of skeletal muscles and stop the human heart.

If you are at new house built according current code, you are likely to have also GFCI or AFCI designed trip before anything bad happens. GFCI can protect in many cases against human touching live wire and ground at the same time. But GFCI does not provide protection in all cases, for example if you have your finger between live and neutral contacts on mains plug. AFCI is designed trip if there is arching on the wiring like bad contact, loose wire or failing insulation on wire. AFCI can detect many problems, but not all.

Generally, when things get hot because of overloading, it’s at the connection point and not in the wire. For instance, a lot of electrical fires start at the plug/socket interface either because the connection is poor, there could be corrosion, etc. And sometimes they can happen when nothing is overloaded! This is one of the circumstances in which arc-fault circuit interrupters can save lives.

Overloading an electrical outlet is a common cause of electrical problems. Theoretically the breaker should protect the outlet against overloads, but it does not always do that especially if outlet or wiring is in bad condition. Do not use cords, plugs or outlets that appear damaged, replace them. Always ensure plugs are fully pushed in. Check all outlets to ensure they are cool to the touch, have protective faceplates and are in proper working order. Only grasp plugs by the plug body, keep fingers away from the front edge near the pins and do not pull plugs out by the cords.


There is a a recommendation that do not use extension cords or multi-outlet converters for appliances, because there are many problems related to US extension cords.

Damaged power cords are a serious residential electrical safety risk, and they are capable of causing both fires and electrocution. All power and extension cords should be checked regularly for signs of fraying and cracking. Power cords should not be stapled into place or run under rugs and furniture.

Besides making sure that the extension cord is in good shape, you need to be really careful that type of extension cord you use in USA. An extension cord essentially is a bundle of insulated electrical wires with a plug on each end. Electrical current flowing through wires generates heat, and when too much current flows through a wire, it can overheat and melt the plastic insulation of the wires, causing short circuits and fires.

But if you use an undersized extension cord to extend the reach of that appliance cord, you can exceed the safe load capacity of the extension cord, and the result can be disastrous.

When purchasing a power cord, consider the electrical load it will carry. A cord with a load of 16 AWG can handle up to 1,375 watts. For heavier loads, use a 14 or 12 AWG cord.

Equipment or in-wall wire heating is normally not a problem when you plug an appliance directly into an outlet using its factory cord because the manufacturer has sized the cord appropriately for the electrical current demand of the device. The size of wiring inside wall is rated based on the breaker size on the mains panel (typically 15A or 20A). The size of the wire on the extension cord can be condiderably thinner, and the mains panel breaker might not protect it against overheating due overload. Some better extension cords can have their own overload breaker built-in but not all.

I think allowing unfused 16 gauge (16AWG = 1.5 mm2) extension cords into the market is a potentially bad link in the chain that we could probably do with cutting out. That wire is still pretty OK up to 15A load current, will get warn. If you plug it to 20A outlet and load with 20A total load, it can get dangerously hot (around 1.8 times more power heating the cable at 20A than at 15A). Pulling 20 amps through that cord made it get very hot quite quickly.

In fairness, it used to be much worse. 18 gauge (maybe even 20 gauge) extension cords were available many years ago, but regulators had the sense to make 16 the minimum as time went on.

There are also small compact ungrounded extension cords that have such designs whete users can plug in plug so wrongly that they are halfway out leaving the live parts so that the live main voltage can be present on the exposed mains plug pins.


Most electrical fires aren’t the result of a single thing; they’re a cascade of individually not-great circumstances combining to make a bad situation. In order to reduce the risk of fires, we’ve continually been making the not-great things less bad.


  1. Tomi Engdahl says:


    Extension Cord companies aren’t gonna like this one! In this video we show you how to wire up your broken extension cords to make them better, safer, and essentially keep them forever. We hope you pick up a tip or two, let us know what you think! Thanks for watching and we’ll see ya on the next one!


    In this video, I do my first electrical project on my own. I think it came out great and was alot of fun. It also got me thinking about future little electric projects.

  2. Tomi Engdahl says:

    6 MISTAKES DIYers Make When Wiring Outlets

    These 6 mistakes that we make as DIYers can be dangerous. Are you familiar with all six and how to wire an outlet or light switch properly and safely? #electrical #diy #tipsandtricks

  3. Tomi Engdahl says:

    BEWARE Of These 3 Common Wiring Mistakes On Outlets & Switches

    90% of homeowners wire outlets wrong, learn how to do it right & AVOID these 3 COMMON ELECTRIC MISTAKES & learn an EASIER way to wire up your outlets with BETTER CONNECTIONS every time.

  4. Tomi Engdahl says:

    How To Wire A Room For Electricity – Bedroom Wiring Rough In

    In this video I will show you how to wire a room for electricity. I take you step by step on how to rough in a bedroom wiring. House wiring for electricity is something I learned over years of wiring my own houses. Electrical for beginners is the audience this is intended for. I go over switch wiring, outlet wiring, ceiling fan wiring, electrical box fill, and much more!

  5. Tomi Engdahl says:

    The BEST power strip for musicians and DJs? Furman SS-6b Quick Look

  6. Tomi Engdahl says:

    Electrical Mistakes That Every Electrician NEEDS To STOP Making!

    Electrical Mistakes That Every Electrician NEEDS To STOP Making!

    Welcome back to Electrician District, today on the channel we are going to check out the Electrical DIY mistakes people have made. Electrical work is dangerous. The Electrical Safety Foundation reported that electricity is the cause of more than $140,000 fires each year, resulting in 400 deaths, 4,000 injuries, and $1.6 billion in property damages. Many DIY (Do-It-Yourself) electrical projects violate building and safety codes and could harm the resale value of your home or business. Unfortunately, people still try to perform their own electrical work despite the dangers. Here is a list of the 5 common DIY mistakes:

    Not Securing the Outlet. It’s a simple thing to do. Make sure the outlet is secured in place. Grab a screwdriver and securely tighten the two screws (one at the top and one at the bottom) to the box behind it. If it’s not firmly held in place, it can move. This can result in electrical arcing, which can result in fire. It can also damage whatever you plug in to them. Securing the outlet also helps when you put on the plate, making sure everything lines up nicely. Not Using GFCI Outlets in Electrical Projects. GFCI stands for ground fault circuit interrupter and it protects people from one form of accidental electrical shock. They monitor the amount of power leaving and returning to the outlet. If a short-circuit routes current through you to the ground, they sense the drop in 1/40th of a second or less and cut the power. GFCI receptacles cut the power any time a slight variation is detected. Proximity to a water source offers a prime example of where a GFCI should appear in an electrical project. Finish this video for more Electrical DIY mistakes people have made.

  7. Tomi Engdahl says:

    AWG – American Wire Gauge Current Ratings
    Amp ratings vs. US AWG wire gauges.

    urces, Tools and Basic Information for Engineering and Design of Technical Applications!

    AWG – American Wire Gauge Current Ratings
    Amp ratings vs. US AWG wire gauges.
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    The AWG – American Wire Gauge – is used as a standard method denoting wire diameter, measuring the diameter of the conductor (the bare wire) with the insulation removed. AWG is sometimes also known as Brown and Sharpe (B&S) Wire Gauge.

    The AWG table below is for a single, solid, round conductor. Because of the small gaps between the strands in a stranded wire, a stranded wire with the same current-carrying capacity and electrical resistance as a solid wire, always have a slightly larger overall diameter.

    The higher the number – the thinner the wire. Typical household wiring is AWG number 12 or 14. Telephone wire is typical AWG 22, 24, or 26.

  8. Tomi Engdahl says:

    How much current can 2.5 mm2 cable carry?
    Current Ratings
    Conductor cross-sectional area, allowable continuous current and stranding. Maximum Current in amps for a single conductor at insulation temperature ratings
    Cross sectional Area mm2 60°C 105°C
    1.5 12 25
    2.5 17 35
    4 22 45

  9. Tomi Engdahl says:

    The reason you’re getting lots of different answers is that there is no hard maximum current a particular cable can handle since it depends on the application.

    You need to specify what physical limit you don’t want to exceed for your “maximum” criterion. Do you want the wire not to rise above ambient temperature some amount? If so, what amount? If you can only tolerate a 10°C rise, then the maximum current will be less than if you can tolerate a 50°C rise, for example. Or maybe the limiting parameter for your application is voltage drop, which could make the maximum current quite different again.

    AWG #16 copper wire has a resistance of 4.016 Ω per 1000 feet, or 4.016 mΩ/foot, or 13.18 mΩ/m. If you need to keep the voltage drop along 1 m of wire to 100 mV or less, then you can’t push more than 7.59 A thru it. If you need to limit the power dissipation to 1 W/foot, then you can’t push more than 15.8 A thru it. 1 W/foot would get noticably warm, but should not be dangerously so for most uses.

    If you are using it for house wiring, then it becomes a legal matter and you simply look up the answer. One chart I looked at says the limit is 3.7 A for “power transmission”. That was chosen to be very conservative so that some amount of degradation and screwups can happen and your house is unlikely to burn down due to overloaded wiring. Legal limits will vary by jurisdiction and which electrical code is being applied. You will have to consult the electrical code that applies to your area and circumstance to get the answer.

    That same chart that shows 3.7 A as the maximum for power transmission also shows 22 A maximum for “chassis wiring”. Presumably more temperature rise is acceptable inside a chassis.

    So to get a straight answer, you have to tell us what you are really trying to do. There simply is no inherent maximum current until you get to where the copper melts. Even that depends on ambient temperature assumptions.

    It is important to note that the current that can flow through a wire depends on a few factors:

    allowable voltage drop. As mentioned in the answer by stevenvh, it depends on the length of wire you are using and the application in question

    allowable temperature of the wire, and insulation

    I’ve usually worked with the idea that a wire at 70 degrees is pretty damn hot. I believe a lot of the time the ratings for cable insulation sheath is rated to 100 degrees.

    If you have 16 AWG wire with a silicon insulation you’ll find its rating to be substantially higher than cheaper plastic insulation.

  10. Tomi Engdahl says:

    How to Wire 208V & 120V, 1-Phase & 3-Phase Main Panel? 3-Φ Load Center Wiring

    In the USA, 208V single phase and three phase voltage is one of the standard voltage levels used for commercial applications. It can be derived from Wye-Wye (Star to Star), Delta-Wye or High leg delta configuration of primary and secondary windings of the transformer.

    In this post, we will consider the Wye-Wye connection for the single phase and three phase 208V and additionally 120V single phase distribution panel wiring.

  11. Tomi Engdahl says:

    How to build a Multi-outlet Power Distribution Box (Power Strip).

    In this video I will show you how to make a multiple outlet Power distribution box (Power strip). It can be convenient for plugging in power tools, DJ equipment or anywhere you need multiple outlet extension cord.

  12. Tomi Engdahl says:


    Extension Cord companies aren’t gonna like this one! In this video we show you how to wire up your broken extension cords to make them better, safer, and essentially keep them forever. We hope you pick up a tip or two, let us know what you think! Thanks for watching and we’ll see ya on the next one!


  13. Tomi Engdahl says:

    What is the difference between an orange isolated ground outlet and a standard outlet?

    This video is a quick explanation of the differences between an orange isolated ground outlet and a standard outlet.

  14. Tomi Engdahl says:

    Isolation Transformers, Variac’s and Current Limiters – Which comes first?

    When setting up a well equipped electronics lab or test bench, there is a proper sequence in which these items should be connected. They are: Isolation Transformer – Variac – Dim Bulb Current Limiter. This video explores the reasons for this sequence.

  15. Tomi Engdahl says:

    How to Fix an Open Neutral Receptacle When the Problem is Upstream in the Circuit

  16. Tomi Engdahl says:

    What is a Hot Ground Reverse?

    One of the few common light configurations on a three-light tester is one that is labeled as a “Hot-Ground Reverse.” This is a very rare situation that would be very difficult (and dangerous) to achieve. However, it is not too difficult to achieve a totally different wiring configuration that can cause a 3-light tester to give the indication of a hot-ground reverse.

  17. Tomi Engdahl says:

    Understanding an Open or Loaded Neutral

    What is a loaded or open neutral, and why did I get a shock from it? This video is about getting a shock from an open or loaded neutral conductor. The problem in this example was an electrical circuit that was being worked on during a renovation. A junction box had been taken apart and the splices undone. When the power was restored to the circuit with these splices not reconnected yet, that’s what caused the condition. The neutral needs to be a direct path back to the panel and never switched, or left undone. Here is more detail on my website that has a diagram to better illustrate the concept.

  18. Tomi Engdahl says:

    How to Wire a GFCI Outlet – What’s Line vs Load? – Electrical Wiring 101

    This video covers the essentials of installing a GFCI Outlet (or GFCI receptacle), including line vs load terminals, wiring basics, why back wiring is OK and much more!

  19. Tomi Engdahl says:

    DEWENWILS Outdoor Extension Cord Cover

    This weatherproof extension cord connection box provides a watertight sealed space to protect outdoor & indoor plug connections from the elements like water, snow, rain, dust, and dirt to ensure circuit safety ( Note: It is just water-resistant. Do not submerse it in water)

  20. Tomi Engdahl says:

    How to DIY install an outdoor outlet

    Hey guys, this is how I installed an outdoor outlet for my new patio. Fairly straight forward, the hardest part is just making sure that everything is water tight.

    Outdoor Outlet from Indoor Outlet Installation

    Extend power from an indoor outlet to an outdoor outlet. Pretty easy to do, just need to make sure you secure power or call an electrician if you are not comfortable doing this kind of work.

  21. Tomi Engdahl says:

    Setting Up and Monitoring Power Distribution for Lighting and Audio with Richard Cadena – Webinar

    Freelance lighting professional, author and trainer Richard Cadena explores safely setting up portable power distribution systems, avoiding problems like overloaded circuits, excessive heat, ground loops and induced noise, proper system monitoring and how to prevent electrical accidents.

  22. Tomi Engdahl says:

    Inspector Finds DANGEROUS Federal Pacific STAB-LOK Electrical Panel

    The Federal Pacific Stab Lok has a history of problems. For safety reasons these panels need to be replaced.
    Here is a informative article about the Federal Pacific Stab Lok panels:

    Federal Pacific Electric Stab-Lok panels are hazardous

    The most notorious electric panel is the Federal Pacific Electric Stab-Lok panel, also known as an FPE panel, Federal Pacific panel, or Stab-Lok. All Stab-Lok panels were made by Federal Pacific Electric, and most panels I’ve found made by Federal Pacific are the Stab-Lok type. In other words, you can usually use these terms interchangeably.

    I recommend the proactive replacement of FPE Stab-Lok panels, whether the panel has previously caused a house to start on fire or not. Here’s why:

    Federal Pacific Electric (FPE) sold millions of panels between the 1950s and 1980s.
    Testing by the Consumer Product Safety Commission has shown these breakers to have an unacceptably high rate of failure, which creates a safety hazard.
    Testing has proven that virtually every panel installed in the United States contains defective breakers.
    FPE committed fraud by falsifying their UL testing, making their UL listing void.
    If a breaker fails to trip when it should, the wires in the home that are supposed to be protected can start on fire.

    So why don’t we recommend having an electrician evaluate the panel? There’s no point. There is nothing that an electrician can do or say to make an FPE Stab-Lok panel safe. Some electricians are under the impression that FPE panels are safe if they can turn every breaker on and off, if every breaker is tightly attached, and if there is no evidence of overheating or scorching in the panel. These things would be dead giveaways that there is a problem, but to truly know if the breaker would trip when it needs to, each breaker would need to actually be tested. This testing would be more expensive than having the entire panel replaced.

    What does it cost to replace a panel? Replacing an old, unsafe electrical panel is not a huge investment. In most cases, the total cost for this project is less than $1,500. Not only does this eliminate the hazards associated with this panel, but all newer panels have the option to have Arc-Fault Circuit Interrupters (AFCIs) installed, for added fire safety. AFCI devices are not available for older Stab-Lok panels.

    The bottom line is that hazards associated with FPE panels are a known issue throughout the electrical, insurance, and home inspection communities.

  23. Tomi Engdahl says:

    How To Add An Outlet To A Finished Wall

    I will walk you through the process of adding an outlet to an existing circuit without going up to the attic or down to the basement. This also will make it so you will have no drywall repair or painting to do after the installation.

    Viewer comments:

    Industrial electrician here – this tutorial was brilliant. It’s so annoying when someone shows how to run wire and they have a big ol basement under it to run it through – ya obviously that’s easy if you got that but most people don’t. The trim trick and even pre-installing the connector was very clever and as someone who does work on his own house I really appreciate it – thanks and bravo!

    Your video taught me a great deal. Until now I’ve been more surgical at this type of work–cutting smaller holes just at the studs, then passing the wire through notches and kick plates. But that leads to occasional difficulties remounting the trim or sheetrock between the added space of the kick plates and their nail-repelling properties. Your method, with the wholesale removal of the sheetrock at the beginning, avoids all those problems and only adds a little extra cleanup. Thank you for showing us!

  24. Tomi Engdahl says:

    A Guide to the 2023 National Electrical Safety Code Updates cover how to incorporate 5G and other technologies

    Since 1914, the National Electrical Safety Code has been a go-to standard for electric and telecom utility companies. The code is updated every five years. The 2023 edition, scheduled to be released on 1 August, becomes effective on 1 February.

    The NESC updates better protect workers, the public, and facilities during the installation, operation, and maintenance of power and communications supplies.


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