What is the point of multiple pole relays?

[Proximity 10+ year member]

Looking at bcae1.com about the relays, and in the table for different types of relays with multiple poles. http://www.bcae1.com/

My question is why? Instead of connecting one wire to each pole, couldn't you just connect all the wires to one pole with the same result?

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[scoob8000 10+ year member]

Looking at bcae1.com about the relays, and in the table for different types of relays with multiple poles. http://www.bcae1.com/
My question is why? Instead of connecting one wire to each pole, couldn't you just connect all the wires to one pole with the same result?

The other poles are all isolated, mainly for controlling different circuits.

As long as your not exceeding the rating of the relay, sure you can connect all your leads to one pole or terminal. Same holds true for switches with more than one pole.

 

[gotparts90 10+ year member]

sometimes you want something to open when something closes. That's the main reason i will use relays with multiple poles. I usually put in 3 pole.

 

[scoob8000 10+ year member]

I just thought of a good example. You could use two four pole relays to switch your speakers between head unit power and amp powered. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Rawr-DQ 10+ year member]

Looking at bcae1.com about the relays, and in the table for different types of relays with multiple poles. http://www.bcae1.com/
My question is why? Instead of connecting one wire to each pole, couldn't you just connect all the wires to one pole with the same result?

Depends, if the wires are all on the same circuit then yes, but if you have something like 220 volts, and 2 legs (voltage is 220 between the legs and 120 to ground/Neutral)

If you wired them together, instead of isolating the circuits you would short out the wires. Same goes if one wire was positive and one wire was negative. All relays have their place and reasons.

A single pole double throw relay is used in electric heat air conditioners. One of the contacts is normally closed, that contact is wired to the heater, the other side is Open and wired to power. When the heater come on, it puts power through the contact to the blower motor turning on the fan. When power is put to the relay, it throws the switch and puts power to the blower motor, turning on the fan.