24v build plate heater vs 120v

  • I'd like to hear other's thoughts on using a 24v build plate heater vs 120v? What concerns would you have stepping up to an AC build plate heater that was properly grounded? Thanks

  • Moderator

    @oozeBot said in 24v build plate heater vs 120v:

    What concerns would you have stepping up to an AC build plate heater that was properly grounded?

    Well that's the biggest thing right there. Safety. Ensuring it's properly grounded and that it stays that way.

    Beyond that there is a "failed on" situation to consider where a thermal runaway could be worse since the 120v heater is likely to also be much higher wattage. (that's the whole point after all isn't it? Get hotter faster.) So having some sort of thermal fuse attached to the heater to kill power in a runaway situation is prudent.

    An inline fuse isn't a bad idea either.

    Going 120v also means you need an SSR. Don't skimp, avoid clones.

    And ensure your 120v wiring is labeled and protected and kept separate from your DC wiring as much as possible.

  • I haven't tried 24v as I went straight to 240v, so can't compare heat times.
    Safety wise you definitely need to consider runaway protection and earth leakage protection.
    In your context I presume you will be selling these machines?
    The big difference is going to be regulatory compliance in your market countries.
    In Australia the importer is legally responsible for compliance with our laws.
    Having a 240v bed puts all the wiring in a different test/compliance class.
    If it was a bed slinger that'd probably introduce more compliance issues with regards to wire type, but I guess any moving bed would fall into that.

  • All good advice.. and yes, the discussion stems from an internal debate we are having on what to offer in our kits. We use 120v for our own machines (switched by an SSR and an added thermal fuse for extra protection), but feel the liability would hinder us from offering them for sale, even stand-alone.

    However, as an aside, our machines are not bed slingers - in fact, the bed is completely stationary as the gantry moves in XY and Z..

  • Moderator

    A good quality 24v heater isn't too bad really. Depends how hot you want to get, how much mass you're heating, how much insulation you have, and how long you're willing to wait. A properly spec'ed 24v silicone heat pad properly installed on an aluminum plate should be able to reach ABS temps in a reasonable amount of time, especially in an enclosure and if insulated on the underside.

    The flip side of 24v heaters is that you now need a more powerful PSU and higher gauge wiring.

    As for compliance, that's for the lawyers, but I suspect that a DIY kit is treated a bit different than a prebuilt system.

  • If you spend the money to get the necessary compliance you will have covered all the safety concerns for wherever that compliance covers.
    Other countries can use that compliance as the basis for their own statements of compliance however in Australia it typically requires additional testing.
    Such things as proving that all wiring insulation is self extinguished in event of fire etc.
    Individuals are not exempt from these responsibilities.
    If I buy one online, I'm legally liable if it electrocuted someone.
    Naturally anyone injured is then going to seek damages from the manufacturer if that's possible.
    Normally it wouldn't be, but if you're in the EU it may be.

  • I appreciate the outside opinions on if we should even consider it. Even though I post here often, we are currently very much still living in a bit of a vacuum as we complete our prototyping. I think the choice is pretty clear in that 24v is the safer, more universal choice, albeit slower..

  • Moderator

    @oozeBot said in 24v build plate heater vs 120v:

    albeit slower..

    Market segment research would tell you if it would be slower relative to your competitors. And even if slower, there's likely a cost advantage there.

  • @Phaedrux Surprisingly, the costs are identical.. and you are right, it would not be any slower than most of the competition. One of the only manufacturers out there with a 120v build plate heater that I am aware of is gCreate..

  • Moderator

    @oozeBot said in 24v build plate heater vs 120v:

    the costs are identical

    Based on hardware and compliance testing combined? That is surprising. I can see how a larger PSU would be offset by the cost of an SSR, and the actual heating elements to be roughly the same, but I would think the compliance requirements would be different for mains powered heaters. But I guess everything would be a surprise to me there because I don't really know my own head from a hole in the ground in this area. Pure speculation.

  • @Phaedrux I'll let this thread die as I think we came to resolution on this, but did want to comment that I did not mean to imply compliance testing costs would be identical..

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