My home is 42 years old. The kitchen lighting consists of 2 48" fluorescent shop lights each plugged into a normal 110v receptable. It uses a standard, 1 way, on/off switch. I want to convert from fluorescent to incandescent and still use the plug. I intend to use a 6 light incandescent vanity bar and low wattage (25w or 40w bulbs). However, since there will not be any other type of fixture being plugged into that receptacle except the incandescent light bar, can I use a dimmer switch without hard wiring the fixture? can I use the plug/receptacle? The circuit uses a 15A circuit breaker. I do not want to violate and electrical building codes.
No, you can't do that. It sounds great until the first time you are short a receptacle and plug in something else - perhaps a vacuum cleaner. And have big problems. Or to give a really bad scenario - your regular receptacle circuits in the kitchen are out but the lighting circuit is working so you move your refrigerator to the "oops, still dimmed" ceiling receptacle on an extension cord until the electrician can get to you...by which time your food has spoiled and your refrigerator ruined.
According to this reference there is a way to do it. But I don't recommend it.
It is usually not that hard to rewire the switch so that it controls a direct (hardwired) lighting fixture instead of a receptacle and change the receptacle to be always on. That is the first step for many people when they buy a house and find that all the light switches control receptacles instead of ceiling fixtures.
It is also very easy (no new wiring involved) to convert a ceiling receptacle to a hardwired light fixture, which would work well for your situation.
But the bigger question is: Why are you switching from fluorescent to incandescent?
You should be switching to LEDs. A LED bulb roughly equivalent to a 40W incandescent (and much brighter than a 25W incandescent) will use around 6W. Plus you'll be replacing incandescent bulbs on a regular basis while the LEDs will last for years. Just make sure you get dimmable LEDs - not all of them are dimmable.
You should also make sure you get enough light. Your 2 48" fluorescent bulbs (if you actually have 2 bulbs in each fixture then the numbers here all get doubled, but I'd actually agree that's more light than you need for a typical kitchen, so I'll stick with the 2 48" bulb scenario) are producing about 2400 lumens each for a total of 4800 lumens. Each 40W incandescent or 6W LED will produce about 450 lumens for a total of 2700 lumens - a little more than half the light. While you may think the current light is too bright, a lot of light is a good thing in a kitchen and the dimmer can give you less light but it can't (obviously) give you more. If you're stuck on screw-in bulbs in a light bar, then something like 12.5W, 75W equivalent, 1100 lumens will do quite nicely. 6 x 1100 = 6600 (more than you have now), total power at full brightness = 6 x 12.5 = 75W (that's less than 2 of your incandescent bulbs) and dimmable so you can lower the light when you want to.
Based on comments, the issue here is more than just making the lights dimmable. There are issues of light quality. Traditional fluorescent "work lights" are relatively poor quality and bother many people due to:
- color temperature
The flickering can be solved very easily with most other lighting technologies, including incandescent, halogen, LED and even more modern fluorescent fixtures.
The brightness problem can be solved, obviously, with a dimmer. I do recommend a dimmer for this situation as it allows for dim light for those who need it and bright light for more typical users. Working in a relatively dark kitchen is fine when you're pouring a cup of coffee. But if you're working on a Thanksgiving feast with chopping & mixing & cooking & baking & 3 people running around, a bit of extra light is very helpful.
Color temperature, CRI and other qualitative factors of a lighting technology have also been dramatically improved with the latest fluorescent and LED bulbs.
- Convert the plug-in fixture to a hardwired multi-bulb (Edison base) fixture
For the average user, I would pick a reasonable-looking LED fixture (i.e., not screw-in bulbs). In your situation since you have serious concerns about light quality, screw-in bulbs provide total flexibility.
Install a LED-compatible dimmer switch. Even if you don't end up using LED bulbs now (but please try - some of them are really good!), that will allow flexibility for any future user. Check the specs carefully - most LED-compatible dimmers are also compatible with a reasonable load of incandescent lighting as well.
Go to a lighting store or a big box store with a decent lighting department and compare light color/quality of the available options.
You're not allowed to dim receptacles, because dimmers put out a really weird wave shape (so they can be cheap). Dimming something other than a dimmable lamp can cause a lot of damage to equipment and can even cause a fire. It can't be "something you remember" because you're not allowed to build a house with dangerous secrets only you know. Doesn't work for guests, tenants, First Responders and the next person who will own the home.
There is one exception; you are allowed to use special receptacles keyed so normal equipment cannot be plugged into it. This requires the lamp(s) get new plugs keyed to fit in the special sockets (and they can also fit normal sockets).
However, due to the weird wave shape, dimmed incandescents can be more flickerey than fluorescents...
... and by the way, if she can see fluorescent flicker, then either she's The Flash, or you are using obsolete fluorescent ballasts (the kind that hum). Upgrade to modern ballasts and lamps and everything that is objectionable about fluorescents just goes away.
If you have a switch controlled receptacle that is then used to power a plug in lighting load you really need to keep the wiring infrastructure as it is. This has already been described in detail.
If you want to be able to have capability to dim the plug in lighting the way to achieve that is to acquire a plug in lamp dimmer. There are a quite a few options available for these now that there is smart technology at play. A plug in module of this sort can even be placed in an inconvenient location and operated remotely via a smart phone or voice assist unit.