# 24v vs 12v solenoid



## Arris138

Is there any good reason to use 24 volt solenoids versus 12 volt in common haunt props? It seems that maybe the 24's are easier to find surplus, but is there any real mechanical advantage?


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## bradbaum

Not mechanical but electrical advantage.

the higher the voltage the lower the current required to fire the solenoid.

P / E = I

24 watts / 24 volts = 1 amp

24 watts / 12 volts = 2 amp

however, due to prop design, sometimes it is easier to use the 12 volts and waste the power.


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## HAUNTEDBARN

You are correct with the PIE formula.. But 1 amp will not change the wire size.In consruction this would effect the price/size on the cable and conduit (much higher amps).I think in this case use the solenoids you have just use the correct transformer of the job.24v or 12v both are low volts/amps.....


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## bradbaum

The values I used were just an example, the actual power a solenoid uses will be much less.

In an automated factory, where hundreds or thousands of solenoid valves are used in a giant machine - the current savings really add up.

In haunting, where we have one or two solenoids - it really doesn't matter. What does mater is matching it to the prop controller, some controllers can only control 12v while others like the PROP-1 sink the current to ground, so again it doesn't matter.


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## HAUNTEDBARN

yes I agree I lov ele. talk...


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## Arris138

Aah, makes sense. Thanks for the quick replies


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## ouizul1

I always thought Power represented the energy used/consumed. If a device consumes 24 watts...it should be the same amount of energy consumed whether it's using 1 amp at 24 volts, or 2 amps at 12 volts, it's still 24 watts, right? 

In this case, a 24 watt solenoid requires a set amount of energy to activate and do it's thing. If the energy is coming down at 24 volts (higher applied pressure) then it only needs 1 amp of current. But at 12 volts (lower applied pressure) it needs 2 amps of current to perform the same workload.


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## HAUNTEDBARN

ouizul1 said:


> I always thought Power represented the energy used/consumed. If a device consumes 24 watts...it should be the same amount of energy consumed whether it's using 1 amp at 24 volts, or 2 amps at 12 volts, it's still 24 watts, right?
> 
> In this case, a 24 watt solenoid requires a set amount of energy to activate and do it's thing. If the energy is coming down at 24 volts (higher applied pressure) then it only needs 1 amp of current. But at 12 volts (lower applied pressure) it needs 2 amps of current to perform the same workload.


you are correct ampsxvolts=watts (volt/amps)..just use the correct wire size and transformer/power supply for the job.If it is going outside add a GFCI too.:googly:


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## GhoulishGadgets

The other thing to remember is the voltage loss over the cable to the solenoid.
This can be a really significant factor and serious issue.

You will get a voltage drop end to end across the cable, dependant upon the current flowing through it and the resistance of the cable.

If a wire is thicker, it will have a lower resistance per length than a thinner wire.

For example, if you had 2 lengths of wire, one is thicker with an overall resistance of 1 ohm, the next is thinner with an overall resistance of 4ohms.

Assuming 1amp flows through both cables...

The voltage drop across the thicker cable would be V = I x R
= 1amp x 1 ohm = 1V

The voltage drop across the thinner cable would be V = I x R
= 1amp x 4 ohm = 4V

That all said....

When you run a higher voltage solenoid, using less current, you will have less voltage loss over the cable.

The worst case example is that you use a long thin cable, the voltage drop over this cable being too great and the actual voltage delivered to the solenoid is too low to drive it.

If you're concerned about your cabling, just use a test meter across the start of the cable, read the input voltage - then check the other end, get the output voltage - you will see if you have a problem.

Remember.. your circuit typically has two wires to your device, not a single wire.. 
Simply run your wire out, twist the wires of one end together and measure the resistance at the other end, this will give you the overall resistance.

Would this be a useful guide with images?? 
Let me know, I'll make one.

Hope that helps.

Si


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## HAUNTEDBARN

GhoulishGadgets said:


> The other thing to remember is the voltage loss over the cable to the solenoid.
> This can be a really significant factor and serious issue.
> 
> You will get a voltage drop end to end across the cable, dependant upon the current flowing through it and the resistance of the cable.
> 
> If a wire is thicker, it will have a lower resistance per length than a thinner wire.
> 
> For example, if you had 2 lengths of wire, one is thicker with an overall resistance of 1 ohm, the next is thinner with an overall resistance of 4ohms.
> 
> Assuming 1amp flows through both cables...
> 
> The voltage drop across the thicker cable would be V = I x R
> = 1amp x 1 ohm = 1V
> 
> The voltage drop across the thinner cable would be V = I x R
> = 1amp x 4 ohm = 4V
> 
> That all said....
> 
> When you run a higher voltage solenoid, using less current, you will have less voltage loss over the cable.
> 
> The worst case example is that you use a long thin cable, the voltage drop over this cable being too great and the actual voltage delivered to the solenoid is too low to drive it.
> 
> If you're concerned about your cabling, just use a test meter across the start of the cable, read the input voltage - then check the other end, get the output voltage - you will see if you have a problem.
> 
> Remember.. your circuit typically has two wires to your device, not a single wire..
> Simply run your wire out, twist the wires of one end together and measure the resistance at the other end, this will give you the overall resistance.
> 
> Would this be a useful guide with images??
> Let me know, I'll make one.
> 
> Hope that helps.
> 
> Si


Yes..Yes... you are correct... resistance is a important factor.Voltage drops should be computed in your circuit..


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