So You Think You Can Replace That Broken Light Switch?

diagram of a single pole switch

the inside of a simple light switch

Take this simple test and see.

That light switch has quit working. Or maybe your significant other desires another color. You can’t afford to hire someone to do it, so you decide it should be fairly simple. Not so fast my friend. You may want to do a little homework first.

I am not a master electrician but I have had extensive experience with home electric repairs. I have had formal training in basic electricity, motor control circuits, and NEC (National Electrical Code) class.

I have come up with this simple test to let you know if you have enough knowledge to change a light switch. If not, some basic information could save your life.

I am leaving a nice space between the questions and answers. So please do not cheat. You will only be cheating yourself.

Here is the test:

1. Describe what a single pole switch is.

2. Which polarity is always the one broken in a single pole switch?

3. Why are the wires black, white, and bare?

4. How do you “kill” the circuit to change a switch?

5. How do you know if a circuit is dead?

6. What is a loop circuit?

7. Why is this white wire marked with black electrical tape?

8. Why are all of these white wires splices together in this electrical box?

9. Does it matter which way I wrap the wire around the screw?

10. Why do the neutral and the ground wires go to the same place in the fuse box? Does that mean they are the same thing?

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1. Describe what a single pole switch is. Answer: a single pole switch is a simple switch with two screw terminals. It is designed to break and connect the connection of a single black wire.

2. Which polarity is always the one broken in a single pole switch? Answer: the “hot” wire is always the one broken. The reason for this is simple. If you break the neutral wire, the circuit will be hot again if it comes in contact with any ground. Break the hot wire and the circuit will always be dead.

3. Why are the wires black, white, and bare? Answer: black is “hot”, white is neutral, and bare (sometimes green) is ground.

4. How do you “kill” the circuit to change a switch? answer: flip the proper breaker in the breaker panel.

5. How do you know if a circuit is dead? Answer: check both wires with a circuit tester or VOM (volt-ohm-meter) do not just assume it because a light has went out.

6. What is a loop circuit? Answer: in a loop circuit, power goes to the ceiling light first and then the switch. Power is broken at the light and looped through the switch. In that case, you will have a white wire and a black wire going to the switch. It may look like a possible problem, but it is perfectly normal.

7.. Why is this white wire marked with black electrical tape? Answer: in certain cases (like a loop circuit) the end of the white wire is marked with black tape or paint to show it is a “hot” conductor. (At least it is supposed to be marked.)

8. Why are all these white wires spices together in this electrical box? Answer: Often times you will encounter several white wires spliced together, when changing a switch. The reason is quite simple. A switch only breaks the black wire. So the white ones need to be spliced to carry on the neutral conductor. If you have a loop circuit (black and white going to a switch), make sure that you mark that white wire with something black, in case the neutral wires become un-spliced. That way they will not get mixed up and cause a short circuit.

9. Does it matter which way I wrap the wire around the screw? Answer: yes, wrap the wire clockwise around the screw terminal. That way it will not want to come off when you tighten it. Often times you can use the quick connect terminals on the back of the switch. The line shows you how much wire to strip and you simply insert it into the hole. If you need to remove the wire, you can place a small flat tip screwdriver in the slot to release the wire.

10. Why do the neutral and the ground wires go to the same place in the fuse box? Does that mean they are the same thing? Answer: The neutral wire is the grounded conductor; the ground wire is the grounding conductor. Electricity runs from the hot (black) to the neutral (white) and into the ground to be neutralized. The bare (or green) wire simply grounds the appliance. That keeps you from getting shocked if anything goes wrong with it.

Anything with a metal chassis will have a green wire running to the “third prong” on its plug. When you plug it in, it connects to the bare wire, which is grounded, and that grounds the appliance.

The ground wire only carries current in case of a short circuit. The white wire carries current whenever anything is on. That is why they both run to the same place (neutral buss bar) in the breaker panel.

Here are my interpretations of the results:

10 of 10 correct. You will have no problem as this is obviously not your first time.

8 of 10 correct. You have a pretty good grasp of basic home electricity

7 of 10 correct. You know quite a bit, but it wouldn’t hurt to refresh your knowledge online.

5 of 10 correct. You know some and you don’t know some. That may be just enough to cause you trouble. Please review what you know and maybe look up some online tutorials.

4 of 10. You need to learn some basic information before you start this project, please!

3 of 10 correct. Hoo boy, what can I say? Get someone to help you or study study study this subject,

2 of 10 correct. Don’t you dare go near that switch!

1of 10 correct. Any money that it costs you to have someone else do this is money well spent.

0 of 10 correct. Are you kidding me? Uh uh. No way, OK? Let someone that knows something about electricity handle this…….please!

And of course, any time you take off the switch or outlet cover and you have no idea what someone has done there, please get some help! Electricity is a wonderful thing and enriches our lives. But is also has the power to take our lives. So please never take any chances and never guess when it comes to this stuff!

electro_master 5 years ago

Not all switches control the hot side of our AC circuit. Older homes would commonly switch the neutrals.

A loop circuit which you are talking about must be a switch loop.

I hate the new code where we identify our neutral with black tape. What are we doing, making it consumer friendly. It really helps to identify switch loops when they are not marked, or heat in a panel, or when working with a three-way. Sometimes I wonder about the guys who write the code.

Here is one for you. Plugs no longer accept 12 wire with a quick-wire connection (friction). That is fine, but why do they still allow these quick-connect blocks used typically in commercial applications with 20 amp circuits. What a discrepancy.

Hope to talk to you in the future. Take care.

gf899 5 years ago from Central Florida Author

Thanks electro_master. You make some very good points :)