Ceiling Fan wiring

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Robert Reed
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Ceiling Fan wiring

Post by Robert Reed » Sat Sep 01, 2012 8:06 pm

I got a used ceiling fan and I want to add a wall switch speed control, rather than the usual fan mounted pull chain. I did a quick and lazy reverse engineering on the fan by opening up its junction box. It looks like the speed is controlled by a capacitor in series with it's armature : Hi-0 mf, Mid-10mf and Lo-5mf. it also appears that the field is tied across the line with a constant 4mf cap in series. I am assuming these are the field windings since they are tied to the rotation reversing switch. My plan is to hard wire the 120v directly to the motor and place the caps (10mf & 5mf) into the wall mount box with its own switch. To verify my findings, I have to tear apart the motor housing, something I really don't want to do. So I thought I would just post it up and see if anyone out there has done this before.

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MrAl
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Re: Ceiling Fan wiring

Post by MrAl » Sun Sep 02, 2012 7:15 am

Hi Robert,

How did you find out that there were three capacitors? Most of the fans i have dealt with have one capacitor and three wires plus a common. The three wires are for the three speeds. Energize each wire one at a time and that gives three different speeds. Yours could be different but i was wondering how you found out it had two or three caps instead of one, and if so, why do you have to take it apart?
If it does have three wires for the three speeds then you'd have to wire all three to the wall box. Not too difficult if you can run your own in wall wiring (using three conductor cable with a ground).
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gerty
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Re: Ceiling Fan wiring

Post by gerty » Sun Sep 02, 2012 8:36 am

Wouldn't the easiest thing be adding a wall mounted variable speed control and leave the the fan itself on high speed.

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Bob Scott
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Re: Ceiling Fan wiring

Post by Bob Scott » Sun Sep 02, 2012 9:51 am

gerty wrote:Wouldn't the easiest thing be adding a wall mounted variable speed control and leave the the fan itself on high speed.
Right. Ceiling fan wall-box controls are available, and they are aproved by UL/CSA. I'm pretty sure that house insurance companies frown upon the installation of home-made electrical devices.
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dacflyer
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Re: Ceiling Fan wiring

Post by dacflyer » Sun Sep 02, 2012 9:13 pm

make sure the wall controller is rated for fans and not lights.. they do make a wall mount switch 3 position. you just leave your fan on high. and control it with the box,.
they used to make a variable speed switch, but now they are all 3 position + off
usually they are in the ceiling fan section.. device looks just like a dimmer switch, but works totally different.
dimmers will not work properly and make the fan hum badly.

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Re: Ceiling Fan wiring

Post by Robert Reed » Sun Sep 02, 2012 9:22 pm

MrAl
As posted I found the caps by opening the fan junction box, a simple procedure. I have seen some ceiling fan internals in the past and they all used caps for speed control. I bet if you took a closer look at yours, you would find out that your "one cap" is actually a dual cap and singled or parrelled for mid & low speed control. There is only one set of wires in mine - hot & neutral wired directly to the ceiling box. all switching is done with fan mounted pull chain switch.

Gerty
I was assuming this was a synchronous motor but not sure. Don't know if phase control would work with this unless it's a universal motor. Hate all that EMI crap anyhow.

Bob
Goodness, in all your years of electronics you don't have any home lab devices mounted to your power lines? :eek:

All
The idea here is simply to transfer the caps to a switch in the wall box;Feed the input with120vac; use existing power line to ceiling box to feed fan motor. I think I have the wiring scheme worked out but this is the first one I have seen with a fixed cap seriesed up to the field winding. A little confused on that part.

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dacflyer
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Re: Ceiling Fan wiring

Post by dacflyer » Sun Sep 02, 2012 9:36 pm

sounds like it'd be more trouble than its worth..and 2nd is there even room in the box.
i'd go for the ready made speed control. they are about $13.00 at Home Cheapo...
and only 2 wires to connect :)

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Bob Scott
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Re: Ceiling Fan wiring

Post by Bob Scott » Tue Sep 04, 2012 9:00 am

Robert Reed wrote:Bob
Goodness, in all your years of electronics you don't have any home lab devices mounted to your power lines? :eek:
Actually, no. Anything I build to attach to the house wiring uses a U ground plug, whether it needs one or not. I've been careful to keep the insurers happy. Which brings up a little piece of irony: My house insurance company has just refused to renew my policy because the house has original aluminum wiring. I have never had it "pigtailed" with copper ends or replaced all the fixtures with cu/al type. I now have an uninsurable house until I get that taken care of.

The entire global insurance business is getting pretty sticky about risk lately, with all the flooding and tornado and hurricane damage claims for big bucks in the USA.
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haklesup
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Re: Ceiling Fan wiring

Post by haklesup » Tue Sep 04, 2012 3:42 pm

Fan speed control switches combined with lamp dimmers are available for wall mounting but unless you have a red and black wire leading to the fan, that would often require rewiring to use. wiring just one switch leaves the lamp or fan on manual pull string

The most convienient solution is a wireless fan controller. Its a small box with pigtails that fits in the fan base and a hand held remote that mounts on a wall hanger. No rewiring is necessary at the wall switch, just a little above the fan at the cieling J box or inside the fan housing. These things are reasonably cheap, usually around $50 to $80.

Well, Bob, at least you're qualified to change out the receptacles yourself. That should have been done 20 years ago, the insurance companies gave you a heck of a grace period since the risk was identified in the 70s. My dad had this done in our house like back in 1980. In addition to changing out all CU/AL receptacles and switches, all the screw terminals were coated in an anti oxidation jel (I forget what it was called but it was brown and smelly). If you can't find the approved fixtures, you will have to do the pigtailing which is way harder and much more work.

Robert Reed
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Re: Ceiling Fan wiring

Post by Robert Reed » Tue Sep 04, 2012 7:01 pm

Bob
What is a U Ground plug?

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MrAl
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Re: Ceiling Fan wiring

Post by MrAl » Wed Sep 05, 2012 5:48 am

Hi Robert,

From what you were saying it sounded like you were not sure about how to wire this up even though you had taken something apart and examined the contents. You said you found three caps and that they appeared to control the speed, so why not try connecting one the way you think it should then and see if it acts the way you think it should.

None of the fans i have worked with in the past have had three caps to control the speed. They all had only one cap and three windings to control the speed low med and high. That's not that there are no fans out there that use caps, but just that i've never had the opportunity to open one up.
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Bob Scott
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Re: Ceiling Fan wiring

Post by Bob Scott » Wed Sep 05, 2012 9:41 am

Robert Reed wrote:What is a U Ground plug?
http://www.acclaim-music.com/Hubbell/Ca ... tors-Bulk/

Maybe it's a Canadianism? The same connectors can be seen at at the US homedepot.com, but the decription does not include "U ground":

http://www.homedepot.com/Electrical-Dim ... reId=10051
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dacflyer
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Re: Ceiling Fan wiring

Post by dacflyer » Wed Sep 05, 2012 1:24 pm

AL wiring was such a failure, i have heard of many houses catching fire or almost catching fire.
multi-strand AL wire it ok, its the single strand wire that is not good... i have seen wires had scorched the paper on fiberglass etc.

i had my insurance cancel on me because i had installed solar panels on my house, i asked my insurance about an increase on my policy, but their understanding was that i was making holes in my roof for skylights.. they did not understand, so i had them come out and have a look, they came out and instantly canceled me policy
their claim was that i had a dangerous dog,, ( cuddly german shepherd ) i had him over 8 yrs and they knew about it. because they seen him and made notes about it way back when i sign on..
IMOP i think they just did not want to add my panels into my policy, and used that excuse to drop me.
i got new insurance 2 days later......and cheaper :D and no clauses about dogs, or solar panels..lol

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Re: Ceiling Fan wiring

Post by Robert Reed » Wed Sep 05, 2012 10:03 pm

Bob
Looks like a garden variety NEMA standard plug to me (for 3 wire cords).Don't know where the "U" fits in other than a vague outline of contact array.

MrAl
Have just completed a lot of internet research and also the opportunity to tear down three more fans (ranging from 3-15 years age) since my original posting. In a nutshell here are my findings:
(1) The motors in all cases were some kind of weird synchronous induction type. They use a split Phase consisting of a rotating magnetic field stator. The fan blades are attached to the rotor.They have many poles (12-16). They have upwards of 2000 ft. of copper wire in the windings.
(2) They all use two capacitors in their speed control. Hi speed -motor direct to line.
Mid speed-Capacitor of value "C" in series with the line
Lo speed- capacitor of value "C" divided by 2 in series with the line.
In all cases capacitor "C" was between 2-10 mf, with 9 mf being the most common.My tear downs used a single case dual cap of 4.5 mf each.
(3) Both windings see this capacitance change. The voltage across these windings were Hi-120vac;Mid- 85vac; Lo- 55 vac. Now as to what changes speed - voltage or phasing, I don't know as I am not fully up to speed when it comes to induction motors, but I do know that they intentionally operate very close to stall speed due to high slippage.
(4) No mention anywhere of three windings and one cap such as your motor. Don't know if yours is an early design or possibly a very high end motor. Was it expensive?

That said, it was a simple matter to control the speed of any of my tear downs by just setting the pull chain to Hi-speed and placing the correct capacitance value in series with the line. These were inserted into the wall box with the proper switch and works just fine. The wall box was originally installed with a standard on-off switch that fed the fan assembly, so it was a simple matter to add speed control in that box.
As Dac flyer mentioned, Home Depot sells these wall mount fan speed controls
for $13. I have to check out two things about these controls - Are they truly capacitive or are they phase choppers like light dimmers? Also if capacitive, the values have to match the particular fan that they are used for.

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MrAl
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Re: Ceiling Fan wiring

Post by MrAl » Thu Sep 06, 2012 12:59 pm

Hi Robert,

Wow that's amazing about you finding several caps in the fans and me finding always only one. Maybe it has something to do with the type of fan. I've played with so many of these things i thought it was almost standard to use one cap and three windings :smile:

Of course i havent opened up every single fan on Earth. But maybe yes these fans were a little more up in price but im not sure now. They were generally high velocity fans that put out a lot of air where you can feel it from 6 feet away with no problem.
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