question

It is always advised to mount things that (can) get warm / hot on a non combustible surface, wood tends to dry out over time to the point of being very easily combustible.

a layer of gipsum (?) board is an easy solution, or a sheet of aluminium (easy to drill / screw through the aluminium into the wood)

JFYI. My 75/15 barely gets warm with 210 watts going into it. My 100/50 gets very hot, with 400+ watts being consumed. I use wood for both and am also looking for something better. I would prefer something like a non combustable plastic or other insulator. I would prefer I not mount it to something that conducts electricity... Just my two cents. -Bill

Boekel, Thank you for your quick response. Gypsum might not be good on a sailboat, but the aluminum makes good sense and something I had be considering. Another thought I have had is to mount the unit say 1/4 inch off of the surface using stand offs. Thoughts?

Thanks bigbillsd, To add some information, The 75/15 is connected to a 30 watt solar array. This is connected to my start battery system on my sail boat. The start battery system is separate from the general use DC power system. The solar array and controller are used to maintain the start battery while I am sailing for prolong or anchor periods. By design the start system is separate form the general system, so as the general system becomes low, I am still able to start the engine to charge batteries. From your note, a 30 watt system should not pose a heat problem.. Eric