I have a project where I will be putting a 180W PSU (80+) and a bunch of N-Channel TO-220 MOSFETS, a few PWM PCBs, and an ESP8266-based controller in a wall cavity for a ≤150W LED lighting system.

  1. If I don't want to PCB-mount the MOSFETs (since this is a one-time design and I'd love to get good heatsinking for the FETs), what material/bar/whatever should I mount them to? Since IIRC I can't mount all to a metal strip since that'd be shorting them all together on their ground side.

  2. This is a new space with decent room in the cavity (≥ 2m^3), so waste heat can go in there, so is there a project box that's OK to receive 110VAC, output lots of 12VDC, and not give an inspector fits?

I'm comfortable with conventional 110V wiring (outlets, switches, fixtures, etc) and I'm comfortable with wiring up ≤10W PCB-based systems (like ESP8266 work), but this combo of house voltage and (marginally) higher wattage is a bit out of my comfort zone and I want to do it safely.

I'm OK with (indeed would prefer) an access panel through the drywall, but would want any fans out the back if possible because of noise. Preferably fans that are heat-activated.

I have a 3d printer and could print something, but I suspect melty thermoplastics are no bueno in this case.

Thanks in advance!

  • \$\begingroup\$ Probably a decent sized junction box with punchout holes for the cabling. An example is powerstarelectricals.co.uk/… \$\endgroup\$
    – Reinderien
    Commented Sep 5, 2017 at 4:12
  • \$\begingroup\$ If there's to be any heat, go metal, and be sure to ground the case. \$\endgroup\$
    – Reinderien
    Commented Sep 5, 2017 at 4:24
  • \$\begingroup\$ Thanks! Assuming I'm freeballing the MOSFETs (i.e. I just have leads running to them, not soldered into a PCB), what do I screw them into? A terminal strip, or...? \$\endgroup\$
    – BJ Black
    Commented Sep 5, 2017 at 4:29
  • \$\begingroup\$ So evidently to220 isolation kits are a thing that I didn't know about. Mica to insulate the MOSFET from a heatsink electrically and use thermal paste on both sides of the mica to transmit heat. Probably good enough for my purposes--just drill/tap appropriate holes into a large heatsink and voilà--a dozen MOSFETs on a block of metal, electrically isolated from each other! I'll also have a look and see if my terminal blocks are spaced right for the 10mm to220 package--might be good enough by itself. \$\endgroup\$
    – BJ Black
    Commented Sep 5, 2017 at 8:28
  • \$\begingroup\$ Can you post your circuit diagram? More often than not it's actually safe to connect the backs together. \$\endgroup\$
    – Reinderien
    Commented Sep 5, 2017 at 11:37


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