Nichrome Wire Calculator

• https://www.easycalculation.com/engineering/electrical/nichrome-wire-calculator.php
• Issue - above calculator does not fix voltage

Procedure

• Select convenient length
• Select max temp - such as 550C = 1000F
• Match gauge to proper voltage drop of 120V
• Find out max gauge that is within current limits (15A) and has correct voltage
• Limit for 15A outlet is 1800W

Sample:

• Remains within 15 amps
• Shows correct voltage
• Max temp - select it to match voltage - you determine max possible temp and judge whether it will burn out your system if you have temperature sensitive components
• Note that Gauge 17 is the max fatness that stays within 1800W
• Note: 22' of 18 ga gets us right at 120V, and 1560W. Good. But temperature of 1260F is a little high.

Examples

8" bed

• 12' of 26 ga draws 450 Watts.
• This was acceptable, but burns out thermistors if placed directly on heater.
• Point: the shorter the nichrome, the hotter it will get while remaining at the correct voltage
• Keep conservative on the bed power,then.
• For same power density on large bed (7W/sq in), would need 4000W of heat. Can't do that. Limit is 1800W. the question is how best to achieve it - what length of nichrome is required for a workable length, while keeping temperature lower rather than higher.

2x2 foot bed

• 1800W limit
• To cover bed - try 6 lines separated by 4" of space. This means 12' + 2 feet return or 14' of sleeve
• Gauge 17, 28' long, gets max 1090 and 1570 watts
• sleeve it in 14' of sleeve. Quite doable.

Links

• 120V Heatbed