The following are the same guidelines found in the Electrical Safety section of the Cool Lights Video. Please read this before completing any electrical projects! We take the operation of electrical devices for granted as an unconscious thing nowadays. You can’t afford to do that once you start building electrical devices…
Electricity will always take the path of least resistance to get to “ground.” If you provide a path to ground, it will use you as it’s conductor with horrible results.
Question: Why does a bird not get shocked on a power line but you might?
Answer: The bird is touching one wire and nothing else. Touching two wires or touching one wire and ground at the same time gives a complete circuit for conductance (also known as a short circuit). The bird is doing neither although there have been instances where a bird with a large wingspan spread it’s wings, touched two wires and was killed. If you tried touching the power line, you would most likely be touching the wire and ground at the same time (probably through a ladder) so you would be electrocuted.
Short Circuits: using a conductor to touch two wires or touching ground while touching one wire yields the same result: a short circuit. If you are part of the conductance path making the short circuit you will be electrocuted.
Water and metal are great conductors. Humans are 75% water!
It should be self-evident but I will say it anyway: leave all devices unplugged from the wall while working on them!
When you are done and ready to plug the device in for the first time, watch for any sparks, smoke or any other danger sign and unplug it immediately. Don’t touch the metal at all during the first power up. Later, after satisfactory test, you should still only touch the metal of your energized device with the back of your hand. The reason for this is that electrocution causes muscle spasms which could very well make you grab the device and not let go–guaranteeing full electrocution. So you should never touch with the palm side of your hand. Touch with the backside of the hand and only one hand,never two.
Grounding of the chassis to properly grounded wall outlets reduces likelihood of shock. Just because you have a three prong plug available doesn’t mean the ground pin is hooked up or even properly grounded in the wall. An ground fault receptacle checker obtained at a home improvement store will go a long way towards verifying this.
Do not count on special insulated gloves or rubber-soled shoes like electricians wear. Unless you are an electrician, never work on an energized device or even one plugged into the wall at all.
Have a partner around the first time you power up your device. If something goes wrong it helps to have two people that coordinate cutting power, etc. There can be some panic when something goes wrong and you have to move fast; two people are better than one.
Under no circumstances touch someone who is being electrocuted unless you want to be also. This is a clear instance where a partner, ready on a cutoff switch, is invaluable.
Use only 3 wire grounded power plugs. White is neutral, black is hot (or sometimes known as “line” also) and green is ground. Do not confuse neutral and ground, they have different functions. Make sure the ground wire is attached to the chassis of your device and that you are plugging into a properly grounded wall plug. Proper wiring of the chassis ground does no good if you plug into what is effectively a 2 prong or ungrounded wall plug.
Regardless of which wire is hot, neutral, or ground in any wall plug, match all color coding inside your chassis. In the USA, black with black, white with white and green with green. Not matching colors can lead to a short circuit.
If the wall plug you are plugging into is wrong, it’s the wall plug that should be corrected, not your device.
No parts of the power from the wall and leading into your chassis should be exposed. Make sure all connections are covered completely with wire nuts, modular connectors, butt splice connectors or electrician’s tape. Do not leave even the slightest part of any power wire conductor exposed.
Use a proper strain relief on your power cord and chassis interface to make sure the plug can’t be pulled out of the chassis.
Water and Electricity
Only work on circuits with dry hands–even when the circuit is not energized.
If there is water on the floor, dry it before using electrical devices.
Never use water to put out an electrical fire, only fire extinguishers rated for electrical fires.
People work with electricity both directly and indirectly every day. Things go wrong even with UL Approved devices built in factories with quality control so always be careful. We forget all the complex chain of events that happens when we flick a power switch and take the process for granted. Actually when you participate in the building of an electrical device, this necessitates a greater level of consciousness on what’s going on “behind the scenes”, so-to-speak. I’ve worked with electricity for around 30 years now and I still don’t take it for granted even today.
Electrical Safety Foundation International
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