I used a remote 12v starter relay, wired direct to my accessory battery, triggered by a momentary push button on the dash. Ran the output from the relay to a 4-gang fuse block and wired the glow plugs parallel, each one fused with a 25-amp fuse. In this set-up, if one glow plug shorts, at least the others won't be affected. The added benefit is that, with the push button activation, the relay only cycles when I need it to cycle, which should extend its years of service. No timer installed, but trial and error gave me an idea of how long to depress based on how the engine turns over at various outside temps. Total cost less than 40 bucks. Fool-proof so far.