Voltage drop on extension cord

My roasting location requires an extension cord. I have a 25’ unmarked cord (probably 16g).

I’ve recorded the voltage from RoasTime under P1-P9 power settings (F3 and D8 held steady) for both a direct connection and using the 25’ 16g extension cord:

There is a 3V drop from the extension cord. I’m not an electrical engineer (I’m a geologist).
It looks like that socket may already be underperforming its 120V potential.

  • I imagine <3% voltage shouldn’t affect my roasts much and I probably won’t upgrade my cord (please let me know if you think otherwise)
  • Also, the voltage did not change while cycling through different Drum Speed and Fan settings without changing Power. Voltage reduction seems to be only influenced by power.

The manual says 'If an extension cord is needed, please make sure it meets the minimum
requirements of power rating" but that seems to fall within the 110-127v range.

At 25’ you’re at risk of too much voltage drop with 16 AWG wire (that’s really small stuff). I think I would choose at least 12 AWG.

Better yet I would suggest rethinking the setup to shorten the length of extension cable needed. Or of all eliminate the cable.

What’s confusing to me is that there is obviously some (fairly long) length of wire running from the circuit panel to the wall outlet. If the extension cord has equal AWG size/rating to the wire running through the wall, what difference does it make? Is there some significant loss in the extra connectors? We don’t get any guidance about selecting an electrical outlet that is within some maximum distance to the circuit panel. Not being critical here at all, just lacking the electrician’s understanding.

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You need at least a 14ga cord- I use a 12ga which would match the wiring from the panel for a 20A circuit, which is what we should be using.

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For typical home construction, a 15 Amp duplex connector would require a minimum of #14 AWG from the circuit breaker in the power panel to that duplex, probably a 20A breaker. That duplex connector may be the only load on that breaker or it may be one of some number strung sequentially from the circuit breaker. So there are potentially other operating loads on the circuit as well as (in this case) the Bullet.

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Grab a cup of coffee (I’m having a dark Sumatra) and hang in with me.

Volts * Amps = Watts
Amps = Watts/Volts

The Bullet has a 1500 W induction board (from what I can find) and the power requirement on the web page states 1550 W. https://aillio.com/?page_id=23112

The Power settings change the wattage output from the induction board.

Assume your chart ryweller, Power @2 is a setting of 750W and Power @9 is 1500W for illustration purposes.

I’m approximating the voltage from your chart.

Extension: Power Setting 2 112 V @ 750W = 6.7 A
Direct: Power Setting 2 113 V @ 750W = 6.64 A
About 1% loss to resistance in the extension cord.

Extension: Power Setting 9 105 V @ 1500W = 14.29 A
Direct: Power Setting 9 108 V @ 1500W = 13.89 A
About 3% loss to resistance in the extension cord.

This is to be expected. Resistance is increased with the cable run and load. The direct connection will always have less resistance given an equal gauge extension because of the shorter run. Less resistance means a higher voltage and a lower amp draw. The longer run has a higher amp draw because of this resistance loss. Higher amp draw equals lower voltage given the relationship.

Think of voltage as pressure and amps as volume. Pulling more volume (amps) out will cause the pressure (voltage) to drop. If you are taking a shower and someone flushes the toilet, your shower pressure drops, same principle. The voltage drops as the amp draw increases which is what your chart is showing.

bradm If the wiring is to code, the outlet distance from the distribution panel shouldn’t matter. What you do downstream from the outlet does. You can calculate the wire gauge needed based on load (amps), run and conductor (copper vs aluminum).

For 20 amps over 25 feet with a 3% allowable voltage drop from source, you need 14g copper, 12g aluminum. 15 amps would be 16g and 12g respectively with a 3% allowable drop. Note: don’t use aluminum. If you want “no effect” over 25 foot at 20amps, an 8g copper would give =< 1 volt drop.

If you are using a 16g 25ft extension, 15 amps is about all you can reliably expect. The cord to the bullet adds a few feet more. Given the 14+ amps the bullet draws @ max, you are within specs but I would want a larger margin of error and not risk a failed roast.

You would also want to make sure you are on a 20 amp circuit, not 15. Watch for other loads on the circuit as well. If you’re drawing close to 15 amps for the Bullet @max, you don’t want to be on the same circuit as a hair dryer, toaster, microwave, etc.

The main power draw is the induction board. The fans, motors, etc. have negligible current draw comparatively so you won’t see much change unless you are doing more precise measuring.

Side bar: If you want to run the Aillio in your RV (we are planning on roasting on the road) a 50 amp setup has about 4 times the power of a 30 amp set up not twice. The 30 is a single 120 source but the 50 is a dual 120 source.

120V * 30A = 3600 W
120V *2 * 50A = 12000 W

Now, time for a refill.


Given the 1550 W power requirement Aillio states and knowing Watts/Volts = Amps;

1550W/110V = 14 amps

You need an extension cord with a minimal rating of 14 amps. The amp rating is usually stated on the label.

This is a 12 g 3 prong cord rated at 15A.


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105V is quite low. The nominal voltage is 120V so a lower wire gauge might be helpful. The V2 is better at compensating for lower input voltages but if you have a V1 you will most definitely get less power.

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I have used an old warhorse US made variac to make sure my voltage is both constant every roast and sufficient to get good roast times. This was all on a HotTop but I believe the premise is the same. I kept 119 V at full power (~124 at the wall). Look on eBay for a used US made one with sufficient Amps to run a bullet. I’m told the Chinese made ones don’t last very long. My bullet comes tomorrow so I will see if it works as it did on the HotTop.

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