Most of the old school dimmers are good for at least 5-15 amps and my bench grinder runs at 15 amps with the dimmer it has never heated up and that's running constant for 20+ mins, i'm pretty sure the hoist will not be be running for more the 30 sec up and down , if the dimmer ever burnt out from two much draw it's replaceable from home depot under $5 , I would just make sure the power cord is 15 amps , this works great for my purposes .

 

Easiest solution.....just get rid of the electric motor and get the Lang hand crank.

I have the Lang with the hand crank....after reading your thread, I'm glad I didn't purchase the electric motor because I was highly considering it.

 

Well, I doubled the line by adding another pulley block and it definitely reduced the speed by about 1/2. I might look at putting double pulleys at 2 points to slow it down even more but I think it will be ok now, without wiring into the unit. I would still like to look into the electrical side becasue I think there will be a time where I would want to reduce or increase the line speed, but I might save this for a winter project when the hardtop isn't hanging from the ceiling. I use to have the hand crank (come-a-long) for my '06 Unlimited a few years ago and it worked great and was really slow when sitting it down on the Jeep but I wanted the electric hoist this time so my wife would also feel comfortable raising and lowering it as well, if she ever needed to.

Thanks for all of the advice and I will definitely come back to all of this over the winter and figure out what will work and won't work and then make the electrical changes.

 

The hoist is rated for home use on a standard outlet and a dimmer switch is as well, building codes have already taken care of the issue.

Also, if you understood motor specs you would know that the max amp draw of the motor is rated at stall. Take a meeter to the motor and you will find it is operating much lower (about half max).

 

Do you care to elaborate on that little tidbit of information?

Most standard dimmers are rated at 300-600 Watts. That comes out to be 5 Amps max for a standard dimmer switch, where a standard outlet is rated to handle 15 amps, which equals 1800 Watts. The last I checked 1800 Watts is higher than a 600 Watt dimmer and much more that a typical run of the mill 300 watt dimmer.

So I'm a bit confused by your statement, because a 1200 Watt heater is also rated for home use, but it sure wouldn't be safe to run that 1200 Watt heater through a 300 Watt dimmer controller switch.

 

Exactly. 3-5 amps max.

But it makes perfect sense to risk fire for the sake of saving $15 off buying something rated for the job

 

Sure, as to the dimmer switch I do agree 600 watts is a very common and available switch any any HD or Lowes. As to the hoist (not sure why you feel a heater is relevant to the hoist), Lange states that the hoist is warrantied through Harbor Freight in their instruction manual so I went to the HF web site for specs. Given that the shipping weight on a 2-Door hard top per the dealer is 90 pounds, I looked at HB's 440 pound capacity motor for specs. This is an assumption on my part, but makes sense. The watts of the 440 pound motor is ratted at 460 watts, well below the 600 watt dimmer switch. Additionally, the 460 watts would only be seen at stall versus the constant duty cycle of raising the hard top would be down around something like 200 watts. Thus, the dimmer is safe for use on the hard top hoist both at constant duty and at stall.

Additonally, as statted by others on this thread, the use of a dimmer for speed control has been a DIY trick used on pollishers, grinders and routers for at least 30 years (my grandfather had this setup when I was a kid, and still does). This has been a well proven method for speed control for many years on motors drawing far more amps than this thread is discussing.

 

That's all well and good, but you still didn't elaborate on your statement about building codes and being rated for "home use" which was what I highlighted in big red letters and had asked for the additional background information on .....thus, which was the reason for me using the heater analogy, because heaters are also rated for "Home use" like you described. What you just explained was the same things you criticized crazymike for outlining you need to do. So now you're criticizing crazymike for outlining things you need to do and now using the same analysis which crazymike outlined for safety precautions?? So how does what you just described above relate to both devices being rated for home use and being taken care of by building codes?

This is the statement I asked you to further elaborate on. I seem to have missed you doing that in your explanation.

 

Sorry, to gain UL listing for a residential aplication the device must demonstrait that it will not result in a fire do to an over current. I meant that the fire risk was covered by code, a risk that is not present because the hoist is within the operation limits of the switch.

 

Very interesting.

So being an electrical engineer you peaked my curiosity. The reason being is that I realize that using a dimmer for controlling a light source, the light element will have a very different load characteristic on a dimmer circuit than using that dimmer to controll a motor attempting to lift over 200lbs of weight. I found it hard to believe that their would be a UL test case that would cover both instances for a single dimmer switch controlling very different loads.

So with my curiosity peaked, I decided to do some homework.

Here's a list from UL's catalog of various device's tests.
http://ulstandardsinfonet.ul.com/catalog/

Quickly scanning through that list I found this test:
Title: Solid State "Dimming" Controls. Clicking on the "scope" of the test brings me to the following page.
Scope for UL 1472

The 1st outline is particularly interesting:
So being an electrical engineer, what that tells me is that the scope of the UL test for the type of dimmer we're discussing is conducted using an intended use case. So in other words, the dimmer is intended to dim lights, then the scope of the test will be using the dimmer while controlling lights.

This now peaked my curiosity even further, where I said to myself, "Well surely there are circuits which control the speeds of motors, so let's look to see if there is another UL test which is different for this type of device. Where I then again quickly scanned through the list of UL Listed tests and found this:
Scope for UL 61800-5-1

So if you bother to read through that link, you see the scope of the test is totally different as I would expect since the load differences between a light element and an electrical motor are very different. A motor with a heavy weight on it and started from a dead stop will have a very high in rush current draw. Physics apply here..."Objects at rest, tend to stay at rest", so it takes more force/power to set a 200lb object into its initial movement. So that 200 lbs current rating you looked up is probably closer to an equivalent 400lb rating or more due to the laws of physics. Not to mention the other differences the circuit would be subjected to like back EMF voltages from a motor that obviously didn't need to get applied as much for a "light" dimmer.

I guess the thing I learned by doing this homework is that the UL listing does not mean that a device will not catch on fire if a max current draw or over voltage is applied to it like you had mentioned. In a very generalized manor, it just means it won't catch on fire under it's intended use. Where the fact of the matter which I further found out, is that by using a "light" dimmer to control the speed of a motor is not the intended use that the product was required to pass to get that UL Listed sticker on it, and that use would make it fall out of the "scope" of the test that you seem to be assuming guarantees that it won't catch on fire by using it to now control the speed of a motor.

Thanks for the education on UL testing, but it seems to me that your assumptions of what UL listed means are not quite correct.