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I recently bought a Titan Aero hot end which came with a 24 V 30 W heater cartridge from E3D. I'd like to use this but the cable length is only 1 meter long and I need it to be 2 meters. The ends terminate with prong connections and there is no polarity to the prongs. How can I safely extend the leads one meter and then connect to my Duet 3 Mainboard 6HC?

Should the cable terminate with a JST connector instead of the prongs to connect to the Duet board?

heater cartridge duet

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Heater polarity doesn't matter

The heater cartridges are just large resistors and so polarity is irrelevant. Either can be positive or negative.

You can extend the leads by cutting and splicing in ~20 gauge wires* to a two pin JST connector line you suggest.


*At 24 volts and 30 watts, you need wire that is rated to carry at least 1.25 amps. The US National Electric Code dictates that this should be 20 gauge wire, but their standard is very conservative. Since you don't need to adhere to NEC codes, you could get away with something thinner (ie higher gauge number).

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1 meter puts you far enough away from the heater than you don't need high temperature wiring to extend it. The larger the guage(e.g. 20 guage) the less resistance you will add to the heater circuit. This doesn't matter as long as you can still achieve your maximum temperature (if you can still achieve the same current without maxing out your voltage on the heater).

Your sensor is where added series resistance is critical. Series resistance to the thermistor will give a negative error in the temperature.

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  • $\begingroup$ I see, looks like for 100k thermistor sensor the difference in resistance is less than 1 Ohm when comparing 250C and 249C so resistance drop here will matter quite a bit. $\endgroup$
    – Feynman137
    Apr 16 at 14:00
  • $\begingroup$ Tarnished or worn out connectors can be an issue with thermistors. $\endgroup$
    – Perry Webb
    Apr 16 at 14:19
  • $\begingroup$ @Feynman137 The absolute value of the temperature doesn't really matter: you just adjust the setting used in the slicer. What would matter would be a poor connection that changes the resistance during a print. $\endgroup$ Apr 16 at 15:33
  • $\begingroup$ @Feynman137 That's true for extensions, but worn our connectors may not keep a constant resistance. That's why they are more of a problem. $\endgroup$
    – Perry Webb
    Apr 16 at 20:26

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