Lesson Learned: Check Your Remotes!

[Dan Case LR]

We had some strange things happening in our bedroom recently. More specifically, strange things with the lights and ceiling fan. We'd come home and find the lights on and the fan spinning, even though we were sure we''d turned them off. More than once. I'd check to be sure before going out to the shop, then later they would be on again. It followed no discernible pattern. We concluded that the cats were walking across the hand-held remote control on the nightstand.

Night before last, I went out to check something in the shop and a short while later my phone rang.

"Did you just do something out there?"

"All I did was turn the dust collector on and off."

"You also turned the bedroom light off. Twice."

My engineer's mind went for everything but the obvious. The startup surge on that new 3hp Leeson motor is big enough to make the wires vibrate in the conduit. Could it be generating some sort of spurious emission that could affect the light controller? Fortunately, good sense returned after a moment, I pulled the wall plug on the cyclone and called her back.

In a moment, we confirmed my second instinct. The stop button on the cyclone remote also toggled the state of the bedroom lights. The two systems used RF remote controls that were on the same frequency and used the same code.

Since the code on the cyclone is non-changeable, I fixed the problem the next day by changing the code on the bedroom light controller. A simple fix (except for having to pull the fan down to get to the receiver and its dip-switches). But it's haunted me ever since.

What if the "start" function on the cyclone had been the same as one of the buttons on the light controller? The Cyclone might have started at random while I was working on it. And what if that had happened when I wasn't in the shop? Before I had the ductwork attached? With no resistance on the inlet, the motor could have burned up if left running. I'm not advocating paranoia, just due caution.

The moral of the story is twofold.

First Lesson: When you get a new remote control for a machine in your shop, know what you're getting and check for conflicts.

If it's an infrared remote (like my Jet air filter or my window AC unit) the remotes can't interfere with something outside your field of vision--they require line-of-sight to work. Just make sure that the new remote doesn't activate any of your other remote controlled stuff in the shop.

You can verify if your new remote is the RF variety by going outside or into another room where there's no line of sight and trying the remote. If it still works, it's the RF variety. Next, check every remote in your premises and make sure your new remote doesn't control anything it shouldn't and no other remotes can control your newly controlled shop device. If you find a conflict, consult the manufacturer's instructions for how to change codes.

If you live close to your neighbors, it wouldn't hurt to check with them, too. It's surprising how much range these little things can have at times.

Second Lesson: I have one more thing to do before I can declare my new cyclone complete. A cutoff switch in a location where it won't be bumped but is still within reach. Just like I did on my table saw and lathe to prevent unwanted startups when not in use (or when curious hands are roaming your shop).

Okay, I'm stepping down from the soapbox now. As you were.

D.

[Steve Peterson]

I am not sure what brand your remotes are, but most RF remotes have switches or jumpers inside the battery compartment that allow you to change frequencies. Some allow you to select A, B, or C. Others have a 4 switches that allow you to pick one of 16 different frequencies.

You might be able to pick different frequencies that don't interfere with the others. It's still a good idea to have a cutoff switch for your cyclone so it doesn't run all night because of a stray RF signal. Some people tie it to the shop lights, so it can't run after you shut off the lights and head back to the house.

Steve

[cody michael]

I have a lamp in my livingroom that randomly shuts off, I think the neighbors have something on the same frequency.

[Steve Peterson]

I have a lamp in my livingroom that randomly shuts off, I think the neighbors have something on the same frequency.

They are probably wondering why their ceiling fan is haunted.

Steve

[Ted Calver]

My dust collector remote turns on one of the fans in the family room. When I turn off the collector, the fan light goes on. We have just gotten used to it

[Dan Hintz]

The startup surge on that new 3hp Leeson motor is big enough to make the wires vibrate in the conduit.

Huh?

.........

[Bill Adamsen]

Now if it turned my teenagers mobile devices off ...

[John Lifer]

When I moved in present home 5yrs ago, I had to use garage as shop. Added x10 remote for dust collector and couple of outlets. Came home one day and found DC running, hadn't used in a week, and no one else home. Changed settings and hasn't read occurred. Assume neighbor had one too.

[Larry Edgerton]

Reminds me of a scene in Grumpy Old Men.....

[Dan Case LR]

I am not sure what brand your remotes are, but most RF remotes have switches or jumpers inside the battery compartment that allow you to change frequencies.

The DC remote is from Oneida and isn't switchable. I'm sure it could be changed by changing jumpers in the remote, but not worth the hassle. Fortunately booth of the remote controlled fan/light units on our house have dipswitches and are easily changed.

I've got to admit that I'm surprised -- and disappointed -- that Oneida used such a low-end wireless remote unit. I guess that's why they're so ready to throw them in free when you order a cyclone.

D.

[John Donofrio]

This thread has me worried that when I get the system up and running I'll go into the shop one day to find the DC running... possibly for days. Yikes.

[Dan Case LR]

Huh?

.........

Every AC motor draws higher current when it's first energized, a fact referred to by the terms "starting current," "startup surge" or "inrush current." Different motor designs behave differently in this respect, and High-Efficiency motors like the 3hp Leeson on my new cyclone are especially fond of high inrush current. I read somewhere that the inrush current on these high-efficiency motors is roughly equal to the locked-rotor current, which in the case of my Leeson is around 100 Amps (vs 10-12 amps in normal operation). Because the inrush lasts only a few seconds, the #12 wire that supplies this motor handles it fine--with one little exception.

During that inrush period, the higher current flow through those wires generates strong 60 Hz magnetic fields that interact with the steel (EMT) conduit where they reside. In many cases where the wire tension is just right the result is audible vibration inside the conduit that can get louder than you might think--loud enough to to scare the whatever out of you the first time you fire it up.

There are several factors that affect how audible this phenomenon is, including size and type of conduit and what else is in it. The biggest factor is how tight the wires are pulled and how full the conduit is, which determines how much they can vibrate. If the electrician that did the install is one of those stingy types who never uses an inch more wire than required and wouldn't upsize a conduit if his life depended on it, the sound will tend to be less prominent. I'm a Service Loops kinda guy who hates overstuffed conduit right at its fill limit, so in my case it's quite audible.

But of course, since I understand what's happening I've learned to ignore that first second or two when the cyclone starts. I usually don't even notice it now, but it's fun to show it to other guys.

D.

[John McClanahan]

The wires resonate at 60 Hz., right? What frequency do the remotes operate at?


John

[Steve Peterson]

The wires resonate at 60 Hz., right? What frequency do the remotes operate at?

There are only a few frequencies available for RF remotes that don't require special transmit licenses. Most operate at 315MHz or 434MHz in the US. Europe might use 868MHz. More expensive devices could be using 2.4GHz. All frequencies are way outside the 60Hz resonance in the wires.

Steve

[Dan Hintz]

Every AC motor draws higher current when it's first energized, a fact referred to by the terms "starting current," "startup surge" or "inrush current." Different motor designs behave differently in this respect, and High-Efficiency motors like the 3hp Leeson on my new cyclone are especially fond of high inrush current. I read somewhere that the inrush current on these high-efficiency motors is roughly equal to the locked-rotor current, which in the case of my Leeson is around 100 Amps (vs 10-12 amps in normal operation). Because the inrush lasts only a few seconds, the #12 wire that supplies this motor handles it fine--with one little exception.

During that inrush period, the higher current flow through those wires generates strong 60 Hz magnetic fields that interact with the steel (EMT) conduit where they reside. In many cases where the wire tension is just right the result is audible vibration inside the conduit that can get louder than you might think--loud enough to to scare the whatever out of you the first time you fire it up.

There are several factors that affect how audible this phenomenon is, including size and type of conduit and what else is in it. The biggest factor is how tight the wires are pulled and how full the conduit is, which determines how much they can vibrate. If the electrician that did the install is one of those stingy types who never uses an inch more wire than required and wouldn't upsize a conduit if his life depended on it, the sound will tend to be less prominent. I'm a Service Loops kinda guy who hates overstuffed conduit right at its fill limit, so in my case it's quite audible.

But of course, since I understand what's happening I've learned to ignore that first second or two when the cyclone starts. I usually don't even notice it now, but it's fun to show it to other guys.

D.

I'm trying to imagine the magnetic field of a single, straight, solid-conductor wire running at 120V that's strong enough to make the cable move within conduit... and I can't.