Instructables

DIY Extension Cord With Built in Switch - Safe, Quick and Simple

Picture of DIY Extension Cord With Built in Switch - Safe, Quick and Simple
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This neat little device solves three problems that I usually come across when experimenting or doing work around the house or out in the yard:

1) No matter how long your extension cord is, it's always three feet too short. My project adds six feet to any extension cord. If you build one you can make the cord as long as you want. Just remember to derate the power of the appliance accordingly.

2) No matter where your extension cord is, you can never find it. Now I have an extra one in case I can't find my other one or if the other one is in use.

3)Some appliances do not have an on/off switch. I am doing some experimenting with hydronic solar thermal collectors and the pump I'm using does not have an on/off switch. To control the pump I have to plug or unplug it, which is annoying. Other things that usually don't come with switches are soldering irons and hot glue guns.

This project is safe because all materials used are CSA approved, the device is properly grounded, wires are properly sized and an appropriate strain relief device is used on the cord.

This project is quick; it only takes about 15 minutes to complete.

This project is simple with only a few components and straight-forward wiring.
 
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mrsayao1 year ago
Cool project... The box I have doesn't have a grounding bar. How would I properly ground the box? I'm making a switch box without the outlet that will allow me to switch on/off a pigtailed garbage disposal under the sink. The electrical outlet available to me is not controlled by any wall switches. The faceplate I have is metal and allows for a waterproof seal around the box while still being able to flip the switch on/off through a lever mechanism. This one linked here is non-metallic but I have a metallic version. Should I remove the vinyl squares too? http://www.lowes.com/pd_89198-334-S2983_0__?productId=3569290

the switch I'm using has a ground lug as well
EcoMotive (author)  mrsayao1 year ago
Hi, if I were you I would buy a combination switch/outlet and wire that up in the device box where your existing outlet is. Hopefully the outlet is the last one on the circuit or on it's own dedicated breaker. Make sure you have good ground first by checking the live and ground holes in the outlet with your voltmeter, it should read somewhere between 110 and 120 volts.
However, if you go the extension cord route, you don't need to ground non-metallic boxes, just make sure that the line ground and the load ground are twisted together with one of the ground wires secured under the green screw in the box.
Please make sure that garbage disposal is properly grounded. If not, your kitchen sink may someday become electricly live and you could get electrocuded if you touch it.
Basically I'm trying to put a switch in line with the live wire in a plastic box. Should I remove the vinyl squares? Can I use a metalic cover or should I switch to plastic.

The disposal has a pigtail connector, black, white and ground. ground on disposal to ground on switch to ground in outlet. Then white neutral on disposal straight through to outlet plug. and lastly the live wire from disposal to terminal of switch then from the other terminal of the switch to the outlet plug. The metal faceplate is a problem though correct?
Nice job. I've been using these for years.

A couple of improvements or options:
1. Use a lighted switch so you know at a glance if it is powered.
2. Use a GFCI plug for extra safety. (which you already stated) I wouldn't use the test button as an on/off. They aren't designed for too many actuations.
3. Make it smaller by using a combination, switch with single outlet. (you can wire the outlet through the switch)
4. Use a higher wattage dimmer switch to control the speed of a small motor driven device like a scroll saw or flexshaft rotary tool (similar to a dremel) Watch the temp of the switch, they can overheat because they aren't really meant to be used that way.
5. Use a rotary timer switch to power your Christmas lights. (Auto off after a couple hours)
6. Use a bigger box and wire a pool pump timer to control your Christmas lights. (quite a bit more money, but the small pre-built ones don't usually handle enough amperage.)
l8nite1 year ago
Thank you for sharing. One of the byproducts of my urban mining http://www.instructables.com/id/Mining-for-suburban-gold/
 is LOTS of electrical cords from lamps, stereos, tv's all kinds of things, the cords themselves are worth money in scrap copper even if the electronic device isn't. I usually just buy a couple of female ends for the longer cords (vacuum cleaners and steam cleaners usually have 10 or more feet of cord) but I'll have to make a couple like this