Determining if Power Supply is Adequate

robfish · Post by **robfish** » Wed Jul 11, 2012 10:55 am

I've moved my Shopsmith to a detached garage which doesn't have adequate power to run the Shopsmith. The electrical outlet I'd use is about a 65 foot run from the house's electrical box, and I'm guessing the wires are 14 AWG.

I no longer use the Shopsmith regularly and don't want to go to the time, expense, and effort of running a dedicated 12 AWG line on a 20 amp circuit to the garage unless it is absolutely necessary.

There is a 15 amp outlet on the outside of the house that is on a circuit that is pretty much unused - if I use that outlet the Shopsmith would be the only thing running.

I am wondering if I can use an ammeter to determine whether on not that outlet and an extension cord would provide enough power to run the Shopsmith without damage.

My thought is that I could lug the Shopsmith over to the outdoor outlet and measure how many amps it drew while starting up at medium speed with the sanding disk and again at the highest speed with no tool (I'm guessing those are the two conditions that draw the most power).

Then I'd run an extension cord made of 12 AWG wire to the garage and repeat my tests with the ammeter.

If the amp draw was awfully close to the same as when plugged directly into the outlet, would that indicate the extension cord would be provide adequate power?

Thanks!

Ed in Tampa · Post by **Ed in Tampa** » Wed Jul 11, 2012 12:02 pm

Rob
If the feed to the garage is 14 guage I would say it is too small.
I think you mentioned you were having dimming lights and etc. That is an obvious clue.

It you have an outlet on the side of the house and you run a "GOOD" 12 gauge 65ft or less extension cord to your Shopsmith you should be fine.

If you shop wisely you may even find a deal on the extension cord. I did I got a top notch with 20 amp plugs on both ends for less than I could buy 12 3 romex for not to mention I would have had to buy plugs and recepticals also.

Since you have an ammeter go ahead and measure the current my guess it will be somewhere between 11-15 amps. Using the extension cord if it is a good one should only add a tiny bit of amperage to those numbers.

If you want to do yourself and the your Shopsmith a favor while you have every thing open to clean out the motor replace the original Shopsmith line cord with 12 gauge cord. I bought a "GOOD" 15 ft 12 gauge extension cord. Cut the female end off and wired it into my Shopsmith.

My Shopsmith could not be happier. It purrs for me even when I'm during full blade buried cuts in 4x4 oak.

dusty · Post by **dusty** » Wed Jul 11, 2012 12:55 pm

I have no argument with suggestions to operate the Mark V on a 20amp circuit while using 12ga wire. However, I contend that you can run your Mark V with no problems at all on a 14gauge, 15 amp service. I have been operating that way for years.

Furthermore, I do not run the speed control down before I shut down.

The fact that you have dimming lights when you turn the Mark V on does indicate that you are experiencing line level loses. The 120 vac service is probably dropping to an unacceptably low level for longer than normal. When the Mark V starts, the line voltage will drop; if starting at high speed, it will drop to less than 100vac for a short time. It is then then that the lights dim. A long extension cord will cause the same symptoms but I think you have said this happens without the long cord. Use your voltmeter and watch the voltage at startup.

If you are plugging the Shopsmith into a duplex outlet, just measure the voltage in the other outlet when you start the Shopsmith. When the current peaks, the line voltage will droop

If this was happening to me, I would go to the breaker panel and tighten ever screw that secures wires to the breakers in the panel. A couple loose connections anywhere in your power panel can cause that phenomena. A loose screw on the breaker that is drawing the load (the Shopsmith line) will certainly do that.

Keep your fingers out of the breaker panel. Insulated screw driver only.

Viewing this might help.

lightnin · Post by **lightnin** » Wed Jul 11, 2012 1:02 pm

I recognize that meter the one on the left in video it's a Simpson 270 just like the 260 except the mirrored scale.
A blast from the past... I got one packed away somewhere.

dusty · Post by **dusty** » Wed Jul 11, 2012 1:17 pm

lightnin wrote:I recognize that meter the one on the left in video it's a Simpson 270 just like the 260 except the mirrored scale.
A blast from the past... I got one packed away somewhere.

The military ruggedized version of that meter is the best multimeter available for this sort of application. Unfortunately, mine disappeared along with a bunch of my tools when I had a home invasion.

The meter, BTW, is a Simpson TS111. It is a specialized version of the typical Simpson. It was originally designed for use by the railroads.

lightnin · Post by **lightnin** » Wed Jul 11, 2012 1:28 pm

OOPS... thought it was a 270 I have a 270 and 260 I usually use a $2.99 cheapo disposable meter unless my LOGAS* is high

*LOGAS = Level of give a s@&#

robfish · Post by **robfish** » Wed Jul 11, 2012 3:53 pm

I watched Dusty's video and have a much more clear idea of what I'll be looking for when I do my testing.

If I understand correctly, if I feed my Shopsmith with a 15 amp breaker connected to 12 AWG wire, there's a chance I'll blow the breaker because the Shopsmith is trying to draw more amps than the breaker's rating, but I probably won't damage the Shopsmith.

On the other hand, if I were to feed my Shopsmith with a 20 amp breaker connected to a really long run of 14 AWG, I probably wouldn't blow the breaker, but I could damage the Shopsmith because the long run of thin wire wouldn't be able to transmit the amount of amps required to drive the Shopsmith.

I'm wonder what kind of damage would be caused in the second scenario, and why.

Thanks!
Rob

Oh... I am going to follow Dusty's suggestion on replacing the Shopsmith's power cord with a heftier SO cord and suspect I'll end up running a new 20 amp circuit with 12 AWG wire to a new electrical outlet on the side of the house closest to the garage, and then use a 20 amp 50' extension cord whenever I work with the Shopsmith. I believe the 20 amp extension cord is made with 10 gauge wire.

Ed in Tampa · Post by **Ed in Tampa** » Wed Jul 11, 2012 4:14 pm

What the video is showing is startup load.
Now Dusty needs to the do the same thing with the Bandsaw mounted. Or while cutting wood. Then instead of the amperage coming down it will stay up nearly to the startup draw and there lies the problem.

Run you Shopsmith at too high an amperage will generate heat, heat will generate destruction sooner or later.

I don't think you are allowed to protect 14 gauge wire with a 20 amp breaker. To use a 20 amp breaker you need at least 12 gauge wire.

Remember the breaker protects the circuit, it does not control the circuit.

If you have a 15 amp breaker you can pull 100 amps for a split second before the breaker blows. The breaker will trip before the 100 amps has a chance to do much damage like making the wire hot enough to ignite.

Dusty is right you can run your Shopsmith on a 15 amp breaker with a 14 gauge wire. But having done it both with 15 amp on 14 gauge and 15 amps on 12 gauge I can tell you the Shopsmith is a lot happier on the 12 wire.

Difference is day and night when doing full blade buried cuts in really hard wood. With 14 guage wire on 15 amp circuit the Shopsmith is laboring and almost any misque movement will stall the blade. With the 12 on the same circuit the Shopsmith is purring along and slight misques on feed will not stall the blade.

JPG · Post by **JPG** » Wed Jul 11, 2012 4:32 pm

The SS is 'designed' to run on a 15A circuit. That assumes no long runs of #14 wire(65' is long').

You were running successfully with a long run AND 2-200W lamps(1.74A) until the start switch got crappy.

So with a #10 extension cord connected to either a 15A or a 20A 'dedicated' circuit it should run well. That would be safer since the lights would not 'go out' if there is a problem with the ss.

IIWM, I would use the existing outdoor outlet with the heaviest(wire gauge) extension cord you could obtain. Using a ground fault interupting receptacle would be a good idea(replace the existing receptacle).

You can do the voltage measuring thing, but it will mean more after doing the IIWM!;) Measuring current is less meaningful than the voltage. It is the voltage drop that causes problems(it drops because of the current and is as good an indication).

Having the sanding disk mounted during startup greatly increases the inertia and therefore the starting time duration.

dusty · Post by **dusty** » Wed Jul 11, 2012 4:51 pm

Ed in Tampa wrote:What the video is showing is startup load.
Now Dusty needs to the do the same thing with the Bandsaw mounted. Or while cutting wood. Then instead of the amperage coming down it will stay up nearly to the startup draw and there lies the problem.

Dusty doesn't need to do this because Dusty knows what will happen. But are you needing to see what the voltage/current draw with a bandsaw load looks like?

Run you Shopsmith at too high an amperage will generate heat, heat will generate destruction sooner or later.

If I understand what you are saying here, I disagree. The Shopsmith (any piece of electrical equipment) will only draw the amount of current that it will draw. It matters not if it is supplied by a 15 amp source, or a 20 amp source or a 60 amp source. If the supply line used in my video had been from a 60 amp breaker, the meters would good exactly as they do.

I don't think you are allowed to protect 14 gauge wire with a 20 amp breaker. To use a 20 amp breaker you need at least 12 gauge wire.

Remember the breaker protects the circuit, it does not control the circuit.

If you have a 15 amp breaker you can pull 100 amps for a split second before the breaker blows. The breaker will trip before the 100 amps has a chance to do much damage like making the wire hot enough to ignite.

Dusty is right you can run your Shopsmith on a 15 amp breaker with a 14 gauge wire. But having done it both with 15 amp on 14 gauge and 15 amps on 12 gauge I can tell you the Shopsmith is a lot happier on the 12 wire.

The Shopsmith will remain as happy as can be as long as the voltage remains up at the levels seen in the video. The voltage going down (like to 105vac and lower and staying) is an indication that the Shopsmith is not seeing 110Vac or better which it won't like.

Difference is day and night when doing full blade buried cuts in really hard wood. With 14 guage wire on 15 amp circuit the Shopsmith is laboring and almost any misque movement will stall the blade. With the 12 on the same circuit the Shopsmith is purring along and slight misques on feed will not stall the blade.

If the Shopsmith continues to run at speed, it is happy. If it bogs down, voltage has dropped (current has peaked) and the Shopsmith will not be happy. Wait too long and the breaker will trip. Do this too much and the motor will heat and when that happens, you'll be unhappy.

I placed my comments in blue and within the quotes for ease of association.