The Lights Turn On, That's All I Know
Electricity has changed our world forever and we depend on electricity for so many things in our daily life. When was the last time you stopped to think about the electrical systems in your house and your own safety when interacting with those systems?
There are two main ways that we interact with power in a house; the power receptacles installed in the wall and the batteries that we find powering many of the devices in our house. When we were little kids our parents always rushed to stop us from putting anything near the power outlet, but they weren’t as quick to stop us from putting the TV remote in our mouths. The TV remote and the power outlet both supply power, so why the difference in protective behavior?
The TV remote is supplied with Direct Current (DC) power from a set of batteries and the wall is supplied with Alternating Current (AC) power from the power grid. Does that mean that DC power is safer than AC power? The answer is; it depends. Both AC and DC power can kill a human at very low amperages which leads to the morbid question that everyone is asking; “how many amps it takes to kill a person?” Yet again the answer is; it depends.
The quick answer is that 0.1 Amps over a period of two seconds is enough to kill a person. To help us understand how small of an amount of electricity that really is, let’s compare that to a standard power outlet in your house which produces 120 volts at 15 Amps. A household power outlet is extremely dangerous, but there is something else within a fingers touch that produces more than 20,000 volts at 15 amps. This amount of electricity is 166 times more voltage while maintaining the same amperage as a power outlet, so what is it, and how dangerous is it?
The act of shuffling your feet while walking across a carpet could produce up to 20,000 volts and 15 amps of electricity. However, the electrical shock is completely exhausted within nanoseconds and due to the resistance of electricity traveling through your skin, the electricity that is produced is harmless.
Charge, Amps, Ohms, Volts, Watts…. What does this all mean? An easy way to think of electricity is in terms of a hose transporting water.
Charge – How much of a water supply there is and its source (AC/DC)
Amps – The size of the water hose and how much water can pass through it
Ohms – The resistance in a hose such as a kink or changes in size
Volts – The pressure inside the hose
Watts – How much water is used
A fire hose hooked up to a fire hydrant could be extremely dangerous because there is a never ending supply of water (Charge), the hose is huge (Amps), there are no kinks in the hose (Ohms), the fire truck pumps the water to a very high pressure (Volts), and the fire fighters will use a significant amount of water (Watts). This is very similar to the AC power outlet in your house.
Fire Hose = Dangerous = AC Power Outlet
Charge – High
Amps – High
Ohms – Low
Volts – High
Watts – High
A garden hose that is used to water the garden is less dangerous because it has a never ending supply of water (Charge), the hose is small (Amps), there are no kinks in the hose but the hose makes a lot of bends (Ohms), the pressure in a house is relatively low (Volts), and the amount of water used is low (Watts). This is very similar to the laptop charger that you would use to charge your DC laptop.
Garden Hose = Not Likely to be Dangerous = DC Power Supply
Charge – High
Amps – Low
Ohms – Medium
Volts – Low
Watts – Low
A watering can is not very dangerous at all because it has a very limited amount of water (Charge), the perforated openings at the end of a watering can are small (Amps), the spout goes from larger to smaller and back to larger again (Ohms), the water is not pressurized (Volts), and there is a very small amount of water used (Watts). This is very similar to batteries found in a TV remote.
Watering Can = Not Dangerous = Small DC Battery
Charge – Low
Amps – Low
Ohms – High
Volts – Low
Watts – Low
A small bowl of water is not dangerous in any way. The bowl has an extremely small amount of water (Charge), however all of the water can be used at once (Amps), there is absolutely no resistance (Ohms), the water isn’t pressurized (Volts), and very little water will be used (Watts). This example is very similar to a static shock that you get after shuffling your feet on the carpet. A static shock that you and I experience has a high voltage and that is because all of the electricity is going through one spot on your finger. For example; your yard might feel a “low voltage” when throwing water out of a bowl and across the yard, but a single delicate flower will feel a “high voltage” if the bowl were dumped directly on the flower all at once.
Small Bowl = Safe = Static Electric Shock
Charge – Extremely Low
Amps – High
Ohms – Low
Volts – Low or high
Watts – Low
Now that we know a little bit more about what makes different types of electricity dangerous, how do we protect ourselves?
There are three common ways of protecting ourselves and the people that enter our home. We could use a Circuit Breaker, a Ground Fault Circuit Interrupter (GFCI), or an Arc Fault Circuit Interrupter (AFCI). Describing the functions of each of these protection devices could take a while, so let’s save that for another time.
In greatly abbreviated and general terms, this is how each device works:
Protects against excess current (Overload)
This would be similar to a moisture meter that automatically turns off the water when the plants in your garden are getting too much water. This will prevent your plants from drowning.
For example: You are vacuuming in the house and your run over the cord. The wires become exposed and contact each other. This creates a short circuit and allows too much electricity to pass through the wires. The circuit breaker would then shut off to prevent a fire.
Protects against an interruption of current (Electrical Shock)
A drip hydroponic garden pumps a nutrient rich water solution from the supply basin at the bottom to the plants at the top of the hydroponic garden. The solution should then return to the basin to be pumped back up again. If too much of the solution didn’t return back to the supply basin then the system would shut down.
For example: You just got out of the shower, the floor and your body are soaking wet, and you plug in your hair dryer. When you start drying your hair water from your hand gets into the hair dryer. Luckily the GFCI outlet is monitoring how much power is going out and back into the outlet, so when you start to get electrocuted the GFCI will shut off the power in much less than 215 milliseconds and save your life.
Protects against arcing (Sparks)
If you had a leaky pipe in the basement of your house that drips just a little bit, over time that leak could damage the foundation or result in a flooded basement. If you had an automatic system that could detect the leaking water and shut off the supply, then your house could be saved from a flood
For Example: You got a new painting that you want to hang in your house. You picked the perfect spot on the wall and drove a 3-inch long nail right through the wall. You placed the painting on the nail, leveled the painting, and everything was perfect. Unfortunately, you pierced an electrical wire when you drove the nail through the wall and now it is creating sparks (Arcing) behind the wall and in a couple of hours your house will be on fire. Fortunately, the AFCI has detected the arcing and has shut off the power saving your house from a catastrophic fire.
Each of these types of protections can be mixed and matched inside of the electrical panel, and the installation of such devices is relatively simple for electricians and do-it-yourselfers who are familiar with electricity. If any of these devices trip it is your obligation as a home owner to determine the cause and keep your house safe.
At Two Moose Home Inspections we check the electrical panel, power outlets, and GFCI outlets in your house and ensure that they are operating correctly. Thank you for reading our article. If you have any questions about residential home inspections, please send us a message. If you would like Two Moose Home Inspections to inspect your property, feel free to schedule an inspection.