Electrical n00b question

[apartmentblower]

ok quick q

My room has a dedicated 30amp 240v circuit hardwired into an intermatic 240v timer. wired into the timer are 4x 240v outlets timed (for ballasts), 2x 120v outlets timed (for cooltube exhaust during lights on) and 2x 120v outlets untimed (for 24/7 fans and misc.).


so i have 4x1000w ballasts = ~20 amps @240v

and then my 120v fans and misc lets say all draw = 4 amps @ 120v


so is my total amperage draw:

20 amps @ 240v + 4 amps @120v = 24 amps total

or is it:

20 amps @ 240v + ((4 amps @ 120v)/2) = 22 amps total



also, so since running this i know its possible to wire a 120v outlet from a 240v circuit using this timer (is this even safe??? ijust told the grow shop i needed to run 4x 240v and 2x120v timed and 2x120v untimed off one timer and they just wired it up for me)... is it at all possible to do the opposite, wire a 240v outlet from a 120v circuit? i dont want to, im just trying to learn...

 

[jwop]

also, so since running this i know its possible to wire a 120v outlet from a 240v circuit using this timer (is this even safe???)... is it at all possible to do the opposite, wire a 240v outlet from a 120v circuit? i dont want to, im just trying to learn...

you would need two 120v circuits to wire a 240v receptacle

i would run a dedicated 120v leg and a dedicated 240v leg ... that way there is no questions ... but im not an electrician or anything

 

[apartmentblower]

ok thanks on the first answer, that makes perfect sense to me cause 240v is 2 hots.

i would run a dedicated 120v leg and a dedicated 240v leg ... that way there is no questions ... but im not an electrician or anything

hmmm... im just asking about safety because in my browsing of the ICmag boards ive never really seen or read anyone mention that they run a 120v receptacle from a 240v circuit... im not an electrician so i dont know if this is standard protocol or even safe. i mean, it works fine right now, and thats how the experienced guy at the grow shop wired the timer for me... i mean it was all wired up for 8x240v outlets and all he did was take one hot from each 240v line and put it into a neutral slot and shazam 4x 120v outlets and 4x 240v. i think.

 

[PharmaCan]

There have been any number of threads about 120v vs 240v here on IC, I'm not sure how you'd search for them.

However, to explain this in the simplest possible terms, here in the USA electricity is delivered to your home in 120v increments. To get 240v, you simply combine two 120v circuits. (It's just a tad more complicated than that, but that's about the easiest way to put it.) Anyhoo, you're not really taking 120v from a 240v circuit, the 240v circuit is actually 2 X 120 volts, so you are just using what is already there.

120v circuits need a neutral, 240v circuits don't need a neutral, they just use two 120v hots. To get 120v from a 240v circuit, you need to add a neutral wire to the configuration.

You can't get a 240v circuit from a 120v circuit. You see, electricity is a sine wave (kinda like if you stacked a bunch of 'S's on top of each other. You can take as much electricity as you want off of one side of the wave and you will still only have only 120v. Running multiple wires off the same side of the wave essentially just amounts to running one bigger wire. To get 240v, you need to take one 120v leg from one side of the wave and then another 120v leg from the other side of the wave and then combine them.

I hope this answers your questions.

PC

 

[apartmentblower]

you are awesome.