Huff-n-Puff Kill-a-Watt

What Is An “Amp Draw” And What Does It Tell Us?

Dave S. from Frankfurt asks, “during my service your tech was using a meter that he plugged my treadmill into. He explained everything as he was working on it, but could you go over it again?”

Certainly, Dave, we’d be happy to. Treadmill amp draws are a very important part of our preventive maintenance service as they are an indicator of overall treadmill health. I find it to be an extremely valuable tool because it involves the precision of math and data, there is absolutely no guesswork. Sure, anybody can come out and slap some lube on your machine or vacuum it out. They may even offer a tip or two about how to extend the longevity of your machine. What separates the professionals from the amateurs are performing an amp draw, and, even more importantly, knowing what to do with that information and how to interpret it.

Kill-a-Watt Meter Plugged Into Wall


This article does go to great depth and is somewhat technical. If you don’t feel like the hassle, this test is performed on every treadmill we work on. Contact Us and we’ll be happy to handle it for you!

In simple terms, your machine’s amp draw measures how hard your machine must work to run. Think of it like your treadmill’s blood pressure. In the same way your heart works to circulate blood through your body, a treadmill requires electricity to flow through its components. The measurement we are taking indicates how much power is flowing through your machine, therefore how hard your machine must work in order to run.

Now, how do we complete this process? To take an amp draw, we have utilized three different methods in the field. I would only recommend the first procedure for a trained professional and someone who is comfortable working around electricity. I have shocked myself doing this, as has every single other tech I have ever met. The second method is better for the home user while the third method is the absolute best. To put it another way, we only utilize the third method now, using number two in rare occurrences and using number one only when we have absolutely no other options.

Method #1: For the first four years we were in business, we used only a standard clamp meter, available at any hardware store. We do not recommend this technique for the home user as the chance of electric shock is higher than I would prefer. Only proceed with this method if you are a trained professional and are comfortable working around electricity. Set your meter to the 20 or 30A setting. With the machine OFF and unplugged, place the clamp around ONE of the power wires going to the motor control board. These are usually white and black. Once again, clamp around only one of them, ensure the clamp closes fully. Hold or place the meter in an area where it does not come into contact with any other components inside the machine while it is powered on. That step is what makes this so difficult. Plug the machine back in, turn the power switch on and proceed with your readings. They will jump around quite a bit, take an average of the numbers you see displayed. As you can see in the pictures below, exposed wiring is present making this hazardous and the meter is in a very difficult position to read.

Method #1: Exposed Internal Treadmill Wiring

Method #1: Wire Selected For Clamp Meter Measurement

Method #2: This upgrade came about in 2011 when we first attended True Fitness certification in St. Louis. Joey Chirchirillo, a repair tech who has seen almost everything, showed our class an extension cord he had fabricated that made this infinitely easier. By removing the outermost layer of this cord and exposing the individual (still coated!) wires, he was able to then plug the machine’s power cord into this extension cord. Therefore he now had plenty of play in the cords to then hold his meter in his hand while using the machine. In the event you chose this method, any alterations made to this extension cord will void the Underwriters Laboratories (UL) certification and should only be used to test the machine for a short (under five minute) period of time. The cord must also be 12AWG or thicker, using a thinner cord than that will result in overheating and possible fire. As a reminder, the smaller the AWG number, the thicker the cord (12AWG is heavier duty than 14AWG). Our Power Extenders are properly rated for this application. Once the machine is plugged in and turned on it is MUCH easier to take these readings. They will jump around quite a bit, take an average of the numbers you see displayed.

Method #2: Thanks Joey, For Saving Our Fingers From Shock And Making This Much Easier To Read!

Method #2: See How Easy This Is Now?

Method #3: This upgrade was discovered during our first SportsArt certification in 2015. Because we’re nerds when it comes to this stuff, we were blown away and haven’t looked back since! Our trainer there was using a Kill-a-Watt amp meter and it made this even easier for us as technicians as well as end users. By plugging the Kill-a-Watt into the outlet, then plugging the machine into that, we saw a much smoother and accurate amp reading which was easier to record in the field after selecting the amp readout. Additionally, we discovered that when plugged into our Power Extenders we gained the best of both worlds, the flexibility of Method #2 with the smooth reading of Method #3! Full disclosure, that is an Amazon affiliate link above, by purchasing through that link we will earn a small commission, thank you for your purchase!

Method #3: The Best Solution To Date!

Method #3: Power Extender Plugged Into Back Of Kill-a-Watt, Treadmill Plugged Into Front Of Kill-a-Watt

No matter which method we use, we take four readings. Prior to lubricating the machine, both loaded and unloaded, as well as loaded and unloaded after lubrication. This allows us to determine a baseline and then determine how lubrication improves the machine’s amp draw. All readings are taken at 4mph, we have found this to be an adequate speed to accurately test the machine while not being too fast than would be safe while walking and holding the cord. Unloaded measurements are taken with no one on the machine, loaded measurements are taken with a user walking on the machine at 4mph. It is important all readings are taken at the same speed.

Unloaded, a very healthy machine should be consuming no more than 2 amps. A moderately healthy machine will be reading 2-4 amps, a mediocre reading is 4-6 amps and anything over 6 amps will undoubtedly signal an issue that will require diagnosing. Loaded readings will be different depending on the weight of each user, but the general rule is that a very healthy machine should be consuming no more than 4-6 amps. A moderately healthy machine will be reading 6-8 amps, a mediocre reading is 8-10 amps and anything over 10 amps will indicate an issue that will require diagnosing. Regardless, the loaded reading should be no more than 4A more than the unloaded reading.

If your amp draw is high unloaded, there is an issue with the system as it is currently running. The issue is NOT going to be the belt and deck (at least not entirely, more on that later). A high unloaded amp draw signals an issue with the drive motor, over tensioned drive belt, bad bearings in the front and/or rear rollers, and/or an over tensioned walking belt. At this point, you will need to isolate each component to determine the issue. Check the tensions of your belts. Are they too taut? Loosen them up, see if that corrects the issue. How easily do the front and rear rollers spin, are they noisy? Do they bind up? If so, they need to be replaced, they should spin freely and quietly. Is your drive motor noisy, does it bind up? If so, the motor will need to be replaced or rebuilt.

Start at the beginning by testing the drive motor’s amp draw only and add components until everything is back together. Disengage the drive belt and test the amp draw. This will give you a reading on the drive motor only. Reinstall the drive belt, check tension and loosen the walking belt so the belt does not spin. This reading will give you the amp draw of the drive motor and front roller. Retension the walking belt, check the tension and take another reading. This will test the entire system and should be similar, if not identical, to the unloaded reading you took before. The component(s) added that resulted in a dramatic spike in amperage will be the source of your issue.

If the amp draw is within specifications while unloaded, but high when loaded, that is indicative of a high amount of friction between the belt and deck surfaces. Lube the machine, walk the lube in and retest. If your amp draw improves to the measurements outlined above, wonderful, your machine is operating as designed!

Excited workout man with red glasses giving thumbs up

Obligatory Stock Thumbs Up Picture. Sorry, I Couldn’t Help Myself

If your amp draw is still high, investigate the belt and deck surfaces. Decks should be completely smooth with a glass-like smoothness under the entire area the belt is over. Belts should be fibrous underneath, with no smooth burn-in spots. If a deck needs to be replaced the belt MUST be replaced as well. If the deck is in great condition, you may get away with just replacing the belt, make absolutely certain the deck surface is perfect prior to making that determination. Below are two examples of decks that should have been replaced long ago. These are extreme examples, once more, the deck must be smooth and free of any imperfections to not require replacement.

Grooved Deck – Over time, the friction between the belt and deck surfaces wore away at the laminate exposing the unlaminated core.

Spiderwebbed Deck – Over time, the heat buildup generated between the belt and deck surfaces will weaken the laminate surface of the deck resulting in cracking. 

By testing your machines amp draw you will be able to accurately determine if components of your machine are in need of replacing. All too often, generally due to a lack of lubrication, we are called out to diagnose a machine with no motor movement. We usually find this is due to a damaged motor control board that overheated due to a high amp draw, caused by the high belt and deck friction which all began with inadequate lubrication. A $20 bottle of lube and basic maintenance could have prevented what has now developed into a $400-$1000+ repair. Once again, if this is more than you would prefer to tackle yourself, Contact Us and we’ll be happy to take care of it for you. Just like your car, proper maintenance is vital to extending a machine’s longevity.

Thank you again for your question Dave, we’re always happy to explain in detail the processes and techniques we utilize to keep your machines in top shape!


Special thanks to Jake Williams at 2nd Wind Exercise in Merrillville, IN for letting us use their showroom for these equipment photographs. 


Ruth in Georgia

Just wanted to say THANK YOU for this very informative and timeless article. Because you shared your expertise, I will buy a gadget through your link, earning you a few cents! :-) BTW, it’s taut, not taught.

And I love your sense of humor!

Dan Thompson

Ahhhhh, how did I make that mistake!?! Thank you for pointing that out, that has been corrected! We’re glad you enjoyed the article, thank you for your purchase!

Duncan Burbidge

Hi there – I did the amp test and all was well. My reading ranged from 1.5A draw at 4mph to 3A when loaded. It only changed by about 10% between lubed and un-lubed. The issue is that the speed will go no higher than about 8mph. A this level the draw is very close to 6A. The machine (Life Fitness T9i) should reach about 12.4mph (20kph). Do you think the issue is likely to be the motor or my power supply? (Or something else!) Many thanks.

Duncan Burbidge

I just had a thought: – I’m on a 230V UK source, so perhaps my readings are all too high (and I should work through the other tweaks)?

Dan Thompson

Hi Duncan, thank you for your inquiry. I believe the amperage should be the same regardless of the input voltage, but don’t want to give you bad info as we’re not familiar with UK power sources. Your best bet would be to contact Life Fitness directly at 01353 665507 or Monday-Friday 8:30 a.m. – 5 p.m. GMT


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