Why are contactors 24VAC?

All the 2-pole, 30A contactors I can find at Grainger are 24VAC. I would prefer 12 or 24 volts DC so I can use a common swithmode wall plug to get the DC and not have to mess with a transformer. What are other brewers using?

BetterSense said:

All the 2-pole, 30A contactors I can find at Grainger are 24VAC. I would prefer 12 or 24 volts DC so I can use a common swithmode wall plug to get the DC and not have to mess with a transformer. What are other brewers using?

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Auber Instruments sells 120VAC contactors. Those are the ones I use.

Heres what I'm using.... http://www.ebrewsupply.com/internal-hardware/contactor.html

Not to be a jerk, but you need to look harder. They're there.

Grainger doesn't even have a category on their site for 24VDC coil voltage. The only choices are 24VAC and 120VAC. It wasn't a question of whether DC contactors exist, but why 24VAC is so popular. Is it safer; like do DC coils have a risk of permanently magnetizing the coil?

What happens if I just buy a 24VAC coil and use DC to switch it?

BetterSense said:

... It wasn't a question of whether DC contactors exist, but why 24VAC is so popular. Is it safer; like do DC coils have a risk of permanently magnetizing the coil?

What happens if I just buy a 24VAC coil and use DC to switch it?

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A guess on why 24VAC contactors are so common is that contactors are common to all HVAC equipment, where 24VAC is standard low voltage. Transforming 240VAC or 208VAC to 24VAC for low voltage use is much simpler than converting it to DC for use.

DC may switch the contactor just fine but you have to consider the current draw, which may be well beyond the wall wart's specs.

Your home heating/AC probably runs on 24VAC generated by a transformer in the furnace. It's the red wire going into the thermostat.

24vdc is a pretty popular control voltage for automation. I wouldn't shop on Grainger because their prices always seem high. Try a dedicated electronics website like Mouser, where you can sort through contactors by coil voltage.

Also try www.automationdirect.com