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Homemade Dimmer Box


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#1 Drew Hoffman

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Posted 05 November 2006 - 09:17 PM

I attempted to build my own dimmer box using a standard light dimmer from Home Depot. I've attached a very crude drawing of the rig, I'm not sure if that makes things simpler or harder. However:

I took an electrical chord shielded with three wires in it already. I attached it to my male edison and ran it through a box. I opened up the middle and snipped one of the cables, attaching a celing light dimmer rated for 1K. The other cable I let run free for a switch configuration and I spliced the ground wire from the dimmer to the ground wire in the cord. Finally I ran it back out of the box and attached it to the female edison. On the dimmer was another wire for a three switch set up which I just trimmed back and taped up.

The problem is that altough the switch will turn on and off... it won't dim.

Can anybody help me understand why this is happening?
Thank you.

dimmer.jpg
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#2 Luke Prendergast

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Posted 05 November 2006 - 09:34 PM

Did you get the input and output the right way around?
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#3 chris evans

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Posted 05 November 2006 - 10:49 PM

Funny. I just built one today too.

I'm not sure if this is your first time making one of these, but the dimmer I purchased is a single pole dimmer with three wires.
One ground
One hot IN
One hot OUT

The ground (green) will obviously be grounded. The neutrals (white) will just pass through. They don't get connected to the dimmer at all. And it really doesn't matter how you do it; the edison male hot (black) will get connected to one wire of the dimmer, and the female edison hot will get connected to the other wire of the dimmer.

If this is how you have it wired and it still only turns on and off, return it and get a new dimmer.

Good luck.
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#4 Hal Smith

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Posted 06 November 2006 - 12:16 AM

The problem is that altough the switch will turn on and off... it won't dim.
dimmer.jpg

The behavior you describe could be because you've hooked up the two "output" wires on the 3-way. If I'm correct, moving either the input or output wire to the unused wire could fix the problem. But it is possible that hooking it up wrong fried the dimmer. :(
Another possibility: home dimmers are rated for home type incandescent bulbs. If you're running the dimmer pretty close to maximum rating, a one or two large bulbs like 1kW BTR's in Babies, on a hot (full open) start might have too much in-rush current for the dimmer and fry it. Large incandescent bulbs are darn near a dead short at turn-on. If you decide to regroup, look at commercial rated dimmers, I've seen them at HD and Lowe's.
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#5 Bob Hayes

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Posted 06 November 2006 - 12:23 AM

If you are having troubles hooking up a dimmer I think you might not want do it. A dimmer is pretty simple and if you do it wrong you could get fried.

And yes, that is a pretty simple drawing.
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#6 alfredoparra

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Posted 08 November 2006 - 10:38 PM

what type of lights are you dimming? hologens require a special dimmer and the home depot rig wont work! you can buy a hologen dimmer kit for about $20.00 if you need for info email me on where to get the dimmer kits
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#7 Michael Morlan

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Posted 08 November 2006 - 11:23 PM

what type of lights are you dimming? hologens require a special dimmer and the home depot rig wont work!


AXP: Um, halogens (incandescents) don't require a special dimmer. You may be thinking of flouros, which do.

Drew: First, you're messing with dangerous stuff here. Second, I highly advise against anyone offering you feedback on electrical issues. This is the domain of certified electricians. If you want to DIY, either seek the help of an electrician, or buy one of the excellent home wiring books at your Home Depot. The Black & Decker publication is particularly good and chock full of photographs and illustrations.

Hope to hear back from you when you're done. ;)
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#8 Hal Smith

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Posted 08 November 2006 - 11:37 PM

Drew: First, you're messing with dangerous stuff here. Second, I highly advise against anyone offering you feedback on electrical issues. This is the domain of certified electricians. If you want to DIY..........

Drew's description of how he went about constructing a DIY dimmer box informed me that he's pretty aware of how to build such a device. I don't disagree with the general principle that a nOOb really should't get too intimate with electrical circuitry but everyone's got to start somewhere. As you point out, a well written home-owner DIY book is a good place to start, B&D's are good, Sunset's are also well done.
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#9 Ken Hendricks

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Posted 09 November 2006 - 01:54 AM

Hey Drew,

There is really no need to build your own dimmers. Harbor Frieght sells a "router speed control" that does the same thing. They are always on sale for less than you can build one, and they work very well. They are good for up to 15 amps! I have yet to find a downside to these:

http://www.harborfre...temnumber=43060

Good luck!

Edited by Ken Hendricks, 09 November 2006 - 01:55 AM.

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#10 Chris Keth

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Posted 09 November 2006 - 03:29 PM

Since the switch works, it sounds to me like you put the neutral wire to the dimmer. If you put a switch in a neutral the switch will work but hot current will still be going through the fixture: a very dangerous situation.
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#11 Matt Sandstrom

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Posted 10 November 2006 - 05:35 AM

there's no "neutral" in one phase ac. after all you're free to plug things in both ways. and either way why would it make a difference which side of the bulb the dimmer was on? this thread is getting more and more confused with each post. i'm surprised so many filmmakers are still alive. :-)

/matt
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#12 Luke Prendergast

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Posted 10 November 2006 - 04:07 PM

there's no "neutral" in one phase ac. after all you're free to plug things in both ways. and either way why would it make a difference which side of the bulb the dimmer was on? this thread is getting more and more confused with each post. i'm surprised so many filmmakers are still alive. :-)

/matt


There is a neutral, an active, and usually an earth/ground. Suggest you don't do any mains wiring without further study.
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#13 Chris Keth

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Posted 10 November 2006 - 05:37 PM

There is a neutral, an active, and usually an earth/ground. Suggest you don't do any mains wiring without further study.


Exactly. The reason you can plug a light in either way is that it doesn't matter which way current runs through a lightbulb, it will still light up.
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#14 Matt Sandstrom

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Posted 11 November 2006 - 09:29 AM

well, there's a wire called neutral, but when wiring a circuit for plugging into a wall socket its function is no different from the other wire. in ac the current alternates in both directions, hence the name. the reason it doesn't matter which way you plug in an ac appliance is not that it works both ways but because there are no "ways".

*all plug in circuits have to assume that the "hot" wire can be either of the two*

/matt

Edited by Matt Sandstrom, 11 November 2006 - 09:30 AM.

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#15 Matt Sandstrom

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Posted 11 November 2006 - 09:41 AM

sorry, i read my first post again and i realize i expressed myself clumsily. the categorical statement made it sound like i meant there was never a neutral wire. there is obviously, just not in this case, which is plug in one phase ac. please don't use my advice the next time you install a washing machine. :-)

/matt

Edited by Matt Sandstrom, 11 November 2006 - 09:43 AM.

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#16 Luke Prendergast

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Posted 11 November 2006 - 04:13 PM

well, there's a wire called neutral, but when wiring a circuit for plugging into a wall socket its function is no different from the other wire. in ac the current alternates in both directions, hence the name. the reason it doesn't matter which way you plug in an ac appliance is not that it works both ways but because there are no "ways".

*all plug in circuits have to assume that the "hot" wire can be either of the two*

/matt


There is a significant safety issue in that the neutral is tied to earth at the fuse box of the building.

Example: If a single pole wall switch is wired to switch neutral rather than active, your toaster will still have live AC even when switched off, so when when you stick a knife in there to get your stuck slice of toast out, after switching it off the wall to be 'safe', KAPOW!

Even if it works, doesn't mean it's right.
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#17 Hal Smith

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Posted 11 November 2006 - 09:38 PM

If the outlet is wired correctly: Looking at the front of a US 120 volt Edison outlet, the wider prong slot is the neutral. If you look at the screw terminals inside a grounding Edison plug (three terminals), you'll notice that one of the blade terminals has a silver screw, and the other blade a copper colored screw. The silver terminal is the neutral and the copper the hot. The ground terminal is green. The National Electric Code requires that color coding - makes it real hard to screw up wiring.

To check outlet wiring, buy a HD or Loews outlet checker, they're pretty cheap, HD has one for $7.94 that also tests ground fault interrupters for proper operation. http://www.homedepot...S....0&MID=9876
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#18 Matt Sandstrom

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Posted 12 November 2006 - 06:53 AM

ok, part of the confusion comes from the fact that european outlets make no difference between the connectors. in some countries, like here in sweden for example, there are even two ground connectors so not even grounded plugs have to be put in a certain way.

as for the safety issues of grounding the neutral, i'm aware of that. i was trying to explain that it doesn't apply *in this case*. sorry for the confusion.

/matt
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