just picked up an old 400w hps wall type fixture plan on fab'n it to hang in my cab, my question is, is my cab even big enough to runn the 400. plan on venting my window A/C into the box with 4" ducting. tho i am sad, had to wire up the ballast since the ppl jus ripped it down with out caring. Ballast fires up can hear it humming tho i think the bulb might be blown since it is not lighting.... hope it actually works and not jus wasting money on a lamp for nothing..... anyway to test the igniter with out buying a new bulb?