Prof. Trace
Dino Challenge No. 2: The saw at the bottom of the garden

Dino Challenge No. 2 · 28 October 2026

The saw at the bottom of the garden

Set by Prof. Trace, answered with one calculator

Prof. Trace has carried the table saw down to the shed at the bottom of the garden. The nearest outlet is on the back wall of the house, so the saw runs on a 100-foot extension cord of 16-gauge copper, which has a resistance of about 4.016 ohms per 1,000 feet of wire. The saw is rated 13 amps and the outlet gives 120 volts.

How many volts are lost in the cord before they reach the saw, and is that inside the 3% the Voltage Drop calculator checks against? Take the copper at room temperature and the current as steady (a motor draws more for a moment as it starts).

Hint. The Voltage Drop calculator in the Electrical folder. Its resistance field is for one wire, per 1,000 feet. Open the Voltage Drop calculator

The answer

The worked answer goes up with the next challenge, planned for 4 November 2026. Follow along with the RSS feed.

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