hey total if i was to use this powerbox http://www.ehydroponics.com/powerbox-dpc-7500-240v-30amp-six-240v-outletshardwire-3-wire.html?sel_size=2580 and use the 3 prong cord since my dryer outlet is 3 prong, i'll be okay since i'll be running all the ballast at 240v correct?
which is better 240v or 120v
- Thread starter bluntmassa1
- Start date
yes
- ETL Listed for use in the United States and Canada
- Built-in digital timer with battery backup
- Six timed 240-volt outlets (6-15r)
- Outlets 5 & 6 switchable to constant power
- Heavy-duty contactor relay to control load switching
- Detachable trigger cord can override the built-in timer, so Powerbox™ can be controlled by other devices
- 5' main power cord, hardwire or plug & play (10-30p or 14-30p)
- Durable powder coated seamless steel enclosure
- All components mounted from the inside for smooth outer surfaces and tight seals to keep out moisture
- Keyhole tabs for easy mounting
- Hand-built at our California factory, 5 year warranty, Legendary Powerbox™ Quality
ScoobyDoobyDoo
Well-Known Member
yep. and just cause you use 240v doesn't mean you can pull more off your breaker panel. 240v is using 2 legs wile 120v is only using 1 leg. so a 100amp panel will give you 100amps at 240v or 200amps at 120v or a combination of both. 240v allows you to run your electronics more efficiently and cooler. as well, it means smaller wire and load to those outlets.
Total.Hydroponic.Control
Active Member
kamie:7622372 said:
Correct.. as long as you have no plans to split off either leg to utilize the 120 volts to ground, you'll be fine.
Total.Hydroponic.Control
Active Member
ScoobyDoobyDoo:7622460 said:
Running 240 vs 120 does NOT reduce the heat. Elecrical losses are electrical losses regardless of voltage. The ballast has a fixed power consumption, along with fix electronic losses. You quoted watts being watts, and you are correct, however to tell someone that running a ballast at a higher voltage will mean cooler output is wrong. The temperature difference between the two operating voltages will be negligible. A watt is a watt... A watt of heat at 120 volts generates the same heat as a watt at 240 volts.
Unless circuit conductors are overloaded at 120 volts, moving to 240 volts will do nothing to decrease temperatures.
i think u are mistaken i qouted what the other guy said
i just said watts is watts
Total.Hydroponic.Control
Active Member
It was in reference to scoobydoos comment.
ok just making sure no one thought that was my position lol
Total.Hydroponic.Control
Active Member
I just don't want people thinking that if they move to 240 volt operation they are becoming more "efficient"... If we are measuring efficiency by power consumption they is absolutely no advantage to running a ballast at 240 vs 120.
The only change in efficiency is wire size. By moving to 240 volts you are reducing the current load, not the power load. Your ballasts run just as warm. You just have to spend less on circuit conductors. Last time I checked copper isn't cheap. If you have a large number of ballasts and you don't want to run several 120 volt circuits, a 240 volt circuit of identical ampacity can effectively carry double the power load.
The only change in efficiency is wire size. By moving to 240 volts you are reducing the current load, not the power load. Your ballasts run just as warm. You just have to spend less on circuit conductors. Last time I checked copper isn't cheap. If you have a large number of ballasts and you don't want to run several 120 volt circuits, a 240 volt circuit of identical ampacity can effectively carry double the power load.
i hear u on that
there are so many misconceptions about running 240 instead of 120
Total.Hydroponic.Control
Active Member
Let's do some more calculations to prove the heat loss difference is negligible.
100 feet of copper has a resistance constant of .158 ohms
Let's say that your outlet is 100 feet from your service panel. That means 200 feet of copper in series with the load circuit... Or twice our constant for a total of .316 ohms.
Another equation of ohms law is P = R x (I ^2), watts equals resistance times current squared.
So let's say our circuit draws 5 amps at 120 volts. To calculate the heat losses of this circuit we plug in the numbers from above.
P(loss) = .316 x (5 ^ 2)
Our circuit is wasting a wopping 7.9 watts of heat dissipation in the branch circuit conductors. Thats not enough to raise or lower the temperature of any sized space, unless your grow room is in a match box.
Now we reduce the current to half because we have doubled the voltage. Run the equation.
P(loss) = .316 x (2.5 ^ 2)
We are now only losing 1.975 watts.. or a quarter of what we previously lost...
Some of you may say "wow look your wrong you do lose more energy with a lower voltage." Let's face the reality of the situation. 7 watts, and 2 watts is laughably insignificant if your going to attempt to justify spending the investment to save the 5 watts difference.
If your goal is to run more ballasts on less circuit runs, 240 volt branch circuits are an attractive choice.
If your goal is to have a cooler running setup, I'm going to laugh at you for spending the money to save 5 watts, when you could invest the money in other viable heat reduction options.
100 feet of copper has a resistance constant of .158 ohms
Let's say that your outlet is 100 feet from your service panel. That means 200 feet of copper in series with the load circuit... Or twice our constant for a total of .316 ohms.
Another equation of ohms law is P = R x (I ^2), watts equals resistance times current squared.
So let's say our circuit draws 5 amps at 120 volts. To calculate the heat losses of this circuit we plug in the numbers from above.
P(loss) = .316 x (5 ^ 2)
Our circuit is wasting a wopping 7.9 watts of heat dissipation in the branch circuit conductors. Thats not enough to raise or lower the temperature of any sized space, unless your grow room is in a match box.
Now we reduce the current to half because we have doubled the voltage. Run the equation.
P(loss) = .316 x (2.5 ^ 2)
We are now only losing 1.975 watts.. or a quarter of what we previously lost...
Some of you may say "wow look your wrong you do lose more energy with a lower voltage." Let's face the reality of the situation. 7 watts, and 2 watts is laughably insignificant if your going to attempt to justify spending the investment to save the 5 watts difference.
If your goal is to run more ballasts on less circuit runs, 240 volt branch circuits are an attractive choice.
If your goal is to have a cooler running setup, I'm going to laugh at you for spending the money to save 5 watts, when you could invest the money in other viable heat reduction options.
skunkd0c
Well-Known Member
the resistance of copper is dependent on length diameter and external heat
weather you apply a 240 or 120 v potential difference across the copper it will not effect the resistance of the wire itself .. but i don't think you meant that
the higher current 120v supply would use thicker wire to support the higher current needed to produce the same wattage at the lower 120v this thicker diameter wire would have less resistance, than the thinner wire used on a 240v ballast and would overall produce less heat and resistance on the load itself .. but it will be tiny
i am not sure what extra lengths you need to goto to run on 240 in the usa,
in the uk you can draw 13 amps at 240 v from a standard wall socket, i prefer to use the metal wallsockets, and rubber plugs
with a standard 6kw contactor unit
the plastic 3pin plugs get pretty hot and crack at getting close to 4kw 15 amps LOL
peace
weather you apply a 240 or 120 v potential difference across the copper it will not effect the resistance of the wire itself .. but i don't think you meant that
the higher current 120v supply would use thicker wire to support the higher current needed to produce the same wattage at the lower 120v this thicker diameter wire would have less resistance, than the thinner wire used on a 240v ballast and would overall produce less heat and resistance on the load itself .. but it will be tiny
i am not sure what extra lengths you need to goto to run on 240 in the usa,
in the uk you can draw 13 amps at 240 v from a standard wall socket, i prefer to use the metal wallsockets, and rubber plugs
with a standard 6kw contactor unit
the plastic 3pin plugs get pretty hot and crack at getting close to 4kw 15 amps LOL
peace
Total.Hydroponic.Control
Active Member
My calculations were done based on 12 gauge wire, and under the assumption that we are only changing voltage not wire size which is the resistance.skunkd0c:7623312 said:the resistance of copper is dependent on length diameter and external heat
weather you apply a 240 or 120 v potential difference across the copper it will not effect the resistance of the wire itself .. but i don't think you meant that
the higher current 120v supply would use thicker wire to support the higher current needed to produce the same wattage at the lower 120v this thicker diameter wire would have less resistance, than the thinner wire used on a 240v ballast and would overall produce less heat and resistance on the load itself .. but it will be tiny
i am not sure what extra lengths you need to goto to run on 240 in the usa,
in the uk you can draw 13 amps at 240 v from a standard wall socket, i prefer to use the metal wallsockets, and rubber plugs
with a standard 6kw contactor unit
the plastic 3pin plugs get pretty hot and crack at getting close to 4kw 15 amps LOL
peace
We can also achieve the same heat loss of the 240 volt circuit in the 120 volt circuit by reducing the resistance of our conductors by a factor of 4, or as you said increasing the wire size. All of this costs money which is why I have consistently stated that moving to a higher voltage for heat reasons is not a smart decision.
Either way, as you can see by the calculations, the power loss difference from 240 vs 120, is insignificant, given a constant wire size. That energy is dissipated along the entire length of wire.... 7 watts distributed over 200 feet of conductors won't even be enough to cause a temperature increase of the conductor.
Your going to have way more heat loss through loose connections than you EVER will from actual conductor resistance.
Total.Hydroponic.Control
Active Member
If you double check my equations you'll see I never changed the resistance value.
skunkd0c
Well-Known Member
to be honest m8, i never knew folk thought they could reduce heat by going to 240 this is a usa thing
in the uk we all use 240 we don't get a choice lol
i agree with you, you are right, its a silly idea thinking changing voltage will make any significant differences to anything
peace
in the uk we all use 240 we don't get a choice lol
i agree with you, you are right, its a silly idea thinking changing voltage will make any significant differences to anything
peace
Total.Hydroponic.Control
Active Member
That's why I'm trying to use science to prove otherwise... It's a myth, that needs to end here.
ScoobyDoobyDoo
Well-Known Member
you are actually incorrect and you quoted me wrong as well. runnin 20amps to 2 1,000w lights will create more heat in the wire than running 10amps will. and electronics run more efficiently at higher voltages. 240v runs more efficient than 120v.
Total.Hydroponic.Control
Active Member
ScoobyDoobyDoo:7623474 said:
Your splitting hairs when you use the word efficiency... The math and theory is all above... Read through it and do the calculations yourself. I studied electrical theory for three years. Just think about copper... It's a conductor, it is chosen as a conductor because it is efficient at transmitting energy without consuming it.. we'll do some more math.
P.loss = .316 x (10 ^ 2) ( 10 amps in your example, at 240 volts.)
31.6 watts of heat loss.
P.loss = .316 x (20 ^ 2) (20 amps for your 120 volt circuit)
126.4 watts of electrical loss...
The difference is 94.8 watts.
Dissipated along 200 feet of conductors.
That's still less than a watt per foot of copper.
I could never in good faith suggest someone spend all the money to upgrade their operation to 240 volts to save 90 watts of heat that's being dissipated by the conductors...
Just remember... These calculations are being done on 200 feet of copper... Most people won't have anywhere near that distance to their outlets.
If your 25 feet away from the outlet in the above example you've just cut the loss to 30 watts....
Additionally most of this copper is in the wall, which means its not even reacting with your environment.
Unless your branch circuits are incredibly long runs... Heat dissipated by conductors carrying current under different potentials shouldn't be a deciding factor when determining an operating voltage... Capacity is the only reason.