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:

    USA ajautui ankariin ongelmiin aivan oudosta syystä: Taloja ei voi rakentaa, koska sähkömuuntajat ovat loppuneet
    Tilannetta ei ole kyetty paikkaamaan, koska USA:n kotimaisen teollisuuden kapasiteetti ei pysy perässä, kertoo New Scientist -lehti.

    Yhdysvaltoja koettelee ankara pula sähkömuuntajista, uutisoi New Scientist. Pulan seurauksena uusien talojen rakentaminen tahmaa, puhumattakaan sähköverkkojen korjaustöistä.

  2. Tomi Engdahl says:

    How to Replace an Electrical Outlet

    This video goes through the details for this simple DIY project to replace a damaged electrical outlet. This is a project that anyone with basic knowledge of how electrical outlets should be able to do.

    00:00 Electrical Outlet Crackling Sounds
    00:48 Why Electrical Outlets Get Damaged
    01:41 Removing the Damaged Electrical Outlet
    05:23 Comparing the Old and New Outlets
    06:18 Connecting the New Electrical Outlet
    10:51 Testing
    13:15 Project Wrap up

    How to Replace an Electrical Outlet – Replace Burnt Out Electrical Outlet and Old Damaged Socket

    If you’re a home owner, at one point or another an electrical outlet will probably have to be replaced. I’m not sure how this one got burnt out but it definitely needs to be changed. It’s pretty easy to do even if you’ve never done it before and I’ll show you step-by-step how to do it with some basic household tools. One of the things needed is a circuit tester. Start with a circuit tester to see if this is an active outlet. Then you’ll have to take off the face plate before the real repair work begins. And turn off the circuit breaker before working on any wiring.

    I bought a 10-pack of Leviton electrical outlets which was actually pretty inexpensive. You could just buy one but since this is a rental house I wanted some extras around in case I had more to replace. A pair of pliers and a screw driver is all that is needed for this DIY project.

    Hopefully in this video I’ve been able to show you how easy it is to replace a bad outlet in your home. I’m not an electrician but I’ve replaced several of these since being a home owner. If this video was helpful please give me a thumbs up and don’t forget to hit the subscribe button so you won’t miss any of my weekly videos!

  3. Tomi Engdahl says:

    #1 Best Video for DIY Electrical Outlet Basics

  4. Tomi Engdahl says:

    Do I have to have a junction box to splice wires?

    0:00 Intro
    01:04 The device
    01:30 How to connect the wires
    08:11 Taking it apart
    09:53 Real life installation
    14:41 Garage apartment build coming soon!

    If you choose to imitate, duplicate or copy anything you may have observed in these videos, you do so at your own risk. The creator of this content does not take any responsibility for any action taken as a result of the information or advice on this YouTube channel (or other platforms) and shall not have any liability in respect of any injury or damage that may result.

  5. Tomi Engdahl says:

    WIRE SPLICING step by step!

    If you need to splice into an existing line, this video will show you how to do it step by step and more importantly, how to do it safely!

    Point of note: when connecting the ground wire to the box, it is better to wrap the ground wire around the screw in a clockwise manner. Helps to self tighten that way. My left-handed brain always wants to go the other way. But at the end of the day, having the ground wire securely fastened is the most important thing.

  6. Tomi Engdahl says:

    Connectors: Which is the Weakest Link

    Here we test 6 common connectors used for household wiring: A standard wire nut aka Marr connector, a heavier duty wire nut Marrette connector, an Ideal In-Sure press-in connector, a Wago 221 Lever Nut connector, a regular 120V outlet connecting wires with its internal press-in connector, and a regular 120V outlet connecting wires with wit screw connectors. We try ever increasing currents from 20 to 70 Amps to see how they hold up to currents way beyond what they were intended for, and then finally over 270 Amps to simulate a short. Two of them even survived that.

    Viewer comments:

    When wires are twisted together the resistive load of the wire nut is zero because the wire nut isn’t need to create the connection. The push in and Wago add a resistive load because there is no direct connection between wires. They’re connected by a thin piece of metal inside the housing, so the probability is higher for failure compared to the wire nut.

    In the 50 years I have been doing electrical wiring I have never had a wire nut joint fail. I have had many push in joints fail to the point I quit using them 40 years ago.I see no advantage in wago connectors.

    I had a wire nut fail. But it was exposed to the elements. The copper oxidized and the nut became the conductor. It was quite an impressive light and pyro show.

  7. Tomi Engdahl says:

    The FIRST Ever Fastest And Easiest To Install Outlet Ever Made! DIYers Best Friend! How To

  8. Tomi Engdahl says:

    GENIUS Electrical Outlet Built-In Features Most People DON’T Know About!

  9. Tomi Engdahl says:

    Easiest Electric Outlet to Install in 100 Years – Safest too!

    This outlet changes everything about how quickly & safely installing an electric outlet can be. It took over 100 years to get to this!

  10. Tomi Engdahl says:

    How To Add an Outlet to an Existing Circuit | Closet

  11. Tomi Engdahl says:

    American vs European Power Sockets: What’s The Difference?

    Today I’m taking a look at a standard power socket from North America and a Schuko one from Europe! We’ll be comparing them and showing how they’re wired up, as well as their respective wall boxes.

  12. Tomi Engdahl says:

    Debunking the Pros: Can WAGO Lever Nuts Handle Heavy Electrical Loads?

  13. Tomi Engdahl says:

    Open Neutral

    Demonstration and explanation of the effects of an “open neutral.”

  14. Tomi Engdahl says:

    Open neutral mini lesson

    Quick lesson on the effect of opening the neutral conductor in a 120/240 circuit.

  15. Tomi Engdahl says:

    Why are Switched Neutrals and Open Neutrals Dangerous

    Switched neutrals and open neutrals are among the many electrical defects we find during a home inspection. Switched neutrals allow power to the outlet being protected by the switch. Instead of breaking the hot wire at the switch, sometimes the neutral wire is mistakenly broken. This allows the power to continue to the outlet presenting a severe safety issue; if someone turned the switch to the off position, the power to the outlet would not be disconnected. If someone were to come into contact with the hot side of the outlet, severe injury or death could occur.

    Open neutrals are not always caused by miswiring a switch. The neutral connection can be broken in s number of ways. Any open neutral circuit presents the possibility of severe or fatal electrical shock. All electrical repairs should be made by a qualified electrician. If this was helpful, please subscribe to our youtube channel Hawley Home Inspections LLC, and visit our website, http://www.HawleyHomeInspectionsLLC, for more articles and videos on home defects maintenance

  16. Tomi Engdahl says:

    What is a Hot Ground Reverse?

    So your three-light outlet tester is telling you that you have a hot ground reverse. Chances are that your three light tester is wrong because it is almost never a real hot-ground reverse.

    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,” but it almost never is. A hot/ground reverse 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. This video shows how a fairly simple problem with the wiring can give the hot-ground reverse indication. I will also give you some tips to help you to locate and repair the problem causing it.

    00:00:00 – Introduction/Correctly Wired Outlet
    00:00:54 – Hot Ground Reverse Indication
    00:02:21 – What is Hot Ground Reverse?
    00:02:47 – 3 Light Testers Not Always Reliable

  17. Tomi Engdahl says:

    120/240 and 120/208 Volt Transformer Secondaries

    Explanation of how we derive 120/240 V and 120/208 V from various Transformer Secondaries.

  18. Tomi Engdahl says:

    The Neutral Conductor and What Happens When it Breaks

  19. Tomi Engdahl says:

    Wye Connected Motor Calculation and Phasor Diagram

  20. Tomi Engdahl says:

    Is the neutral wire safe? – Powerlines

    Deadly current exists on grounded wires – Powerlines

  21. Tomi Engdahl says:

    Understanding an Equipotential Protective Grounding Zone

  22. Tomi Engdahl says:

    Measuring VOLTAGE on 3 and 4 wire Dryers and Ranges. Be a Pro. Learn from the Pros.

    3 and 4 Wire Range/Dryer Cords Explained

  23. Tomi Engdahl says:

    In today’s very competitive marketplace you need reliability, so you need to use circuit breakers that are high quality and technically correct for your application. Altech is a US leader in DIN rail mounted breakers with ratings up to 63A. Only Altech offers DIN rail mounted breakers that meet UL489, UL508 or UL1077 approvals with a short circuit interrupt capacity of up to 10kA. No other manufacturer offers this complete line. This assures you the right product for your application requirements.

    When you need branch circuit protection, Altech offers UL489 Miniature Molded Case Circuit Breakers in both AC and DC voltages. The AC version offers dual voltage rated circuit breakers at 0.2-63A/240VAC and 0.2-32A/480Y/277VAC in 1-3 poles. The DC version offers 0.2-63A at 125V (1 pole) and 250V (2 pole).

    If your application requires a manual motor controller, Altech is the leading US supplier of UL508 Manual Motor Controllers (MMC). In AC, we offer up to 60A in 1 to 3 poles at 480Y/277VAC. With 6 trip curves, Altech has the largest selection in the industry. This ensures you the selectivity you require for your application designs. Our MMCs have a 10kA short circuit withstand capacity, this is the highest rating in the industry. The AC version is rated up to 60A and is DC rated in 2 poles up to 80VDC.

    When your application requires supplemental protection for control circuits and on the load side of branch circuit protectors Altech has solutions. We offer a competitive line of AC Supplementary Protectors, up to 63A, in 1 to 3 poles at 480Y/277VAC with a 10kA short circuit withstand rating.

  24. Tomi Engdahl says:

    Why are CamLock dangerous? Often refereed to as ‘suicide connectors’, CamLock was outlawed across Europe because of the dangerous nature of the product. The connector has no locking system, cable strain relief or safety features that allow it to be disconnected under load, which is incredibly hazardous.

    CamLock Connector Alternative for US Industry

  25. Tomi Engdahl says:

    How I wire a panel (an in-depth tutorial)

    How To Neatly Wire A Residential Panel | Karly the Sparky

  26. Tomi Engdahl says:

    5 Common Electrical Panel Mistakes

    Joel continues to highlight some best practices pertaining to electrical panels and some errors left behind by a previous sub-contractor, particularly an incompatibility breaker, debris inside the panel, and mediocre mounting practices.

    Laced within the technical instruction are recommendations and points of professionalism employed daily by Jefferson Electric masters, journeymen, & apprentices.

  27. Tomi Engdahl says:

    How to Wire an Electrical Panel – Square D

    Attention! Square D QO Recalls Electrical Panels

  28. Tomi Engdahl says:

    What is a CAFI Circuit Breaker and How are They Installed on a Plug-On Neutral Load Center?

    How to install a Square D Arc Fault breaker/ why

  29. Tomi Engdahl says:

    How to find a circuit breaker – How to trace a circuit – The Electrical Guide

  30. Tomi Engdahl says:

    Troubleshooting 480v Light poles

    Step by step tutorial of how I figure out issues with 377/480v light poles in this commercial location! Part one I ordered all the material to have all of this fixed so once I get it I’ll be doing a new video on how I untangle those wires and fix basically everything lol #lextheelectrician #bluecollarbabe #electrician #electriciansoftiktok #commercialelectrician

  31. Tomi Engdahl says:


    Full tutorial of fixing this burnt to Sh$t panel. Equipment failure absolutely charred every single wire that was attached to this panel. So we are going to remove it and replace with a brand new panel and clean up all these wires. I’ll explain exactly how I go about replacing a panel.

  32. Tomi Engdahl says:

    Relocating an MLO (sub panel), branch circuits, & feeder to a new location | Tinton Falls, N.J.

    100A to 200A Panel Upgrade with Portable Generator Wiring

  33. Tomi Engdahl says:

    How to Properly Test Outlets with a Multimeter 5 Ways

    When electrical issues arise, these quick receptacle power tests will come in handy. Learn how to measure voltage, conduct a polarity test, and more.

    Ever wonder if power is reaching an outlet? The voltage reading on a multitester or multimeter can tell you. When you test outlets with a multimeter, you can tell whether the white and black wires are reversed, the receptacle is grounded correctly, and which cable entering the box feeds power to the outlet.

    If you don’t have a multimeter, you can use a voltage detector instead of the voltmeter and a continuity tester ($8, Home Depot) instead of the ohmmeter. If a problem arises with an electrical receptacle in your home, you can usually diagnose it by running one of these outlet tests

  34. Tomi Engdahl says:

    How To Test If A Wire Is Hot With A Multimeter (IN 6 STEPS)

    How to test if a wire is hot with a multimeter

  35. Tomi Engdahl says:

    Aluminum wire is notorious for catching fire, you’re lucky and yes, it should be replaced.

    They got away with aluminum wiring in houses for a while but found out the hard way to many times it just isn’t the same as copper and requires special everything.

    Aluminum wire isn’t in and of itself bad. The wires coming into your main breaker are very likely aluminum. For sure the wires coming into the meter base are. The problems arise when cooper and aluminum are improperly joined. The oxidation at those joints leads to higher resistance and can eventually lead to a fire.

    Wouldn’t hurt to have them all checked.
    Aluminum wire needs a product like Noalox on it or it oxidizes.
    It is also soft a and a bit of heat between the wire and the outlet screw can get it to disform a bit and go oval…..then is gets loose under the screw….then more heat…then more disforming …ect….ect..
    Good idea to make sure they are all clean and tight at the very least.

  36. Tomi Engdahl says:

    Federal Pacific was wiped out when they had to do settlements in their class action lawsuit

  37. Tomi Engdahl says:

    why does it warn against using on aluminum wiring?

    aluminum creeps and loosens under a screw connector, causing a high-resistance connection that gets hot under load. Aluminum wiring was common in mobile homes and caused many house fires. Spring-loaded connectors are made for safe use with aluminum wiring.

    bimetallic junction heating.

    Mercury also corrodes aluminum. That’s why it’s forbidden to bring aboard an aircraft.

  38. Tomi Engdahl says:

    I have a question.
    Why do some hospitals/doctors offices have their outlets mounted with the earth ground up?
    Some traditional….
    Was there a code timeline on this?

    Chad P DuBose there was a recent change to the Electrical Code- outlets should be mounted with the ground pin on top. The idea is something falling onto a partially inserted plug will contact ground instead of line voltage. I’ve never heard of that actually happening. But I never heard of electrocutions on metal garage doors from the opener either, but there’s a few deaths per year in the US and the updated code requires a GFCI.

    **Update** I stand corrected a bit. The Natl Electrical Code in the US does not dictate outlet orientation. NEC suggests that the ground pin on top has a safety advantage. However, ground pin on top *IS* a code requirement in many healthcare settings. The reason is the possiblility of an arc/spark while oxygen could be nearby.

    The large plugs are standard hospital-grade plugs, designed to be more tolerant of abuse and not expose wires. All AC cords, outlets, and equipment in patient care areas are tested periodically for leakage current. The limit depends on whether patient contact with equipment is incidental (lamp or hospital bed), skin contact (EKG), or under the skin (IV infusion pump).

    in certain commercial or medical environments this is code, even outlets have to be tested for tension. No less than 4 oz.

    NFPA 99.
    Healthcare facilities specific. But only if adopted by the jurisdiction.

  39. Tomi Engdahl says:

    Electrical safety basics Don’t work with exposed conductors carrying 50 volts or more. Make sure electrical equipment is properly connected, grounded and in good working order. Extension cords may not be used as permanent wiring and should be removed after temporary use for an activity or event.

  40. Tomi Engdahl says:

    80% of People Use the Wrong Screwdriver For Electrical Work

  41. Tomi Engdahl says:

    7 FATAL Wiring Mistakes Most DIYers Don’t Know They Are Making | Most Are Guilty of 3

    In this video I cover some of the biggest, most common, and potentially dangerous mistakes that people make when connecting electrical wires together. We are going to look at the mistakes of using wire nuts, wagos, and the wiring itself. Then I will show the correct ways each should be done and some better practices.


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