I agree, 38AC, the standard junction boxes you can get at any electrical supply house are a very good choice and are often priced right. I used a die cast aluminum box with lid that I had on hand. I put the bridge in a bigger box on the wall with my homebrew AVR, it's 240-120 step down transformer and the adjustable power resistor for the harmonic backup system; I figured why vibrate the bridge and it's spade connections when I don't have to. The wall box also has a DPDT switch for brush polarity reversing, a switch for AVR or Harmonic selection and the manual flash field buttons. I should have put the voltage, current and frequency meters in that box but they predated the homebrew AVR.