30amp @240v = 60amp @120v ?

[cocktail frank]

30A @ 240v = 60a @120v?
HELL NO
you can only pull 30 amps at 120v, per leg.
wire size on the 2 pole 30amp breaker is still 10 awg.
10awg is good for 30a only.

 

[bluenorth]

Well now you guy's got me all confused! I thought with a double pole breaker on 240v you basically have 2 30 amp circuts at 120v sharing a neutral. The double pole breaker has 2 breaker switches in one breaker for each hot? Does anyone really know their stuff! Hey cocktail frank, you can only pull 30amps on 10awg but you have 2 hots so why can you draw 2x30amps

 

[cocktail frank]

doesnt work like that.
your pulling 30 amps on each phase.
doesnt total to 60a at 120v.
its still 30a at 120v.

 

[FarmerTed]

Well now you guy's got me all confused! I thought with a double pole breaker on 240v you basically have 2 30 amp circuts at 120v sharing a neutral. The double pole breaker has 2 breaker switches in one breaker for each hot? Does anyone really know their stuff! Hey cocktail frank, you can only pull 30amps on 10awg but you have 2 hots so why can you draw 2x30amps

No, you have one 30a circuit and no there are not 2 breaker switches. The reason you can not replace a 30a 240v with 2 30a 120v is because you would most likely exceed the 60a main circuit breakers capacity.
Look at it this way, amps refers to rate of electrical flow. If you had a 2 inch water pipe with 30 gal of flow per minute & you split the end into two 1 inch pipes your total flow would still be 30 gpm. 15gpm through one pipe & 15gpm through the other.
If your main breaker is 60a, add up all the breakers in your box. The total cannot exceed 60a.

 

[bluenorth]

Okay, but your not splitting the warter pipe at the end, you are running four wires (pipes) right from the main breaker. the 2 hots have 120v each, the neutral, and the ground. It's my understanding that if you check your dryer recepticle there is an x and y slot, both would read at 120v. If you combine these 2 hot wires you will get 240v. The 2 seperate hot wires are 10awg capable of carrying 30amps each. I may be mistaken but I think your talking about 240v on a 2 wire (plus ground) cable that cannot be split to create a 120v circut. Someone should be able to put this to rest, I'll have to hop over to an electrical site for a clear answer.

 

[cocktail frank]

you need a neutral to get 120v.
if the 2pole 30amp breaker is only on a 2 wire (2 hots and a ground)
you cant safely have 120v.

 

[bluenorth]

I appreciate your help, cause I'm getting more confused or your playing with me. In a 10-3 wire there is a neutral. We are talking about running a line for a dryer, a 10-3 from a 30 amp double pole 240v breaker. You can test at your dryer receptacle, if you check between x and y you get 240v, x or y with white or ground (against code to use ground)you get 120. So I'm sure you can get 120v from a 30amp 240v circut. The question is; that x and y both carry 120v but can they both carry 30amps as they are sharing a neutral?

 

[FarmerTed]

Ok, you are talking about a 120/240 appliance circuit. The recepticle has 4 prongs,yes? the way its wired 2 prongs draw power from each hot to power the heating element of your dryer at 240. 1 prong only draws from 1 hot, this is for your control panel which operates on 120. I guess i assumed you were talking about a straight 240 recepticle, something used for an appliance that doesnt require any 120. Say a large compresser in your garage. Maybe i misunderstood your intentions. I thought you wanted to remove the 30a 240v circuit and replace it with 15a or 20a 120v circuits. You know, the kind you plug your lamps and stuff into. Or did you actually want a 30a 120v circuit?
I guess my water pipe explanation was clear as mud, sorry i tried. What i was trying to say was if your main breaker is 60a and you have 1 30a 240v and 2 15a 120v circuits you're drawing as much as you can because they total 60a. If you remove the 30a 240v you cannot safely add 2 30a 120v circuits. This would add up to 90amps when you only have 60a into your sub-panel. Drawing 90a would continually trip your main 60a breaker. Hope this helps to clarify-FT

 

[fumancu]

The total number of single breakers can exceed the total of the main.All the small breakers are not useing there max power.If you did happen to over power the main it will trip.on the 240v line he can get two 120v lines. If he has a 30amp double pole breaker he can get 2 15 amp 120v lines without changeing the wire.If he has a dryer outlet he could buy a dryer plug and wire 2 120v outlet boxes on the cord.

 

[FarmerTed]

The total number of single breakers can exceed the total of the main.All the small breakers are not useing there max power.If you did happen to over power the main it will trip.on the 240v line he can get two 120v lines. If he has a 30amp double pole breaker he can get 2 15 amp 120v lines without changeing the wire.If he has a dryer outlet he could buy a dryer plug and wire 2 120v outlet boxes on the cord.

I was incorrect when i said the total amps of your breakers cannot exceed the amps of the main breaker. The 30a 240v circuit could be broken down into 2 30a 120v or 4 15a 120v and still draw the same wattage. I believe total watts of everything drawing power from your sub / 240v=minimum amps of main breaker. Example would be 12,000watts/240v=50 amp main breaker.

 

[PurplePotion]

This thread is trashed. I don't think anyone would know what to do after all of these garbage conflicting posts. Good luck to the OP .. I think I would be pulling my hair out by now.

 

[Guest]

30A @ 240v = 60a @120v?
HELL NO

Wrong

doesnt work like that.

Yeah, it does.

your pulling 30 amps on each phase.
doesnt total to 60a at 120v.
its still 30a at 120v.

That's wrong frank, you need to think about what you're saying.

 

[cocktail frank]

im not gonna argue with you, im done arguing w/ people when it comes to what i do for a living.
but.......
a 30amp line, regardless of the voltage, consists of what wire size?
if you are thinking 10 awg cu or 8 awg al, you are correct.

now tell me,
how can you get 60amps off a 10 awg line?

 

[cocktail frank]

Kingmaker is 110% WRONG!!! 30 amps @ 240 volts = TWO 15 amp single pole breakers @ 120 volts thus being 30 amps. Don't be making people burn down their house because you do not know what you're talking about!!!!!!!

dude, sorry to say, but you are wrong yourself.
30a at 240v is a double pole breaker.
thus having a 30 amp draw on each (of the 2) hot legs aka phases.
if you replace this dp 30a breaker w/ 2 15 amp 120v breakers,
you can still only draw 15amps a piece at 120v.
breaker size is the rating of the circuit, 15 amp.
ultimately, wire size will give you the maximum breaker size you can use.
if it is 10 awg wire, you can top out at 30amp.

if you mean pulling out the dp 30a breaker and installing tandem breakers, or piggybacks, then you could fit 4 single 15a breakers in the space open from the dp 30 being pulled out.
but you could only free up space for NEW circuits this way.
you still have the 2 10awg wires that the original dp 30a was on.
so, youre in the same perdicament you were in from the get-go.

 

[Guest]

im not gonna argue with you, im done arguing w/ people when it comes to what i do for a living.
but.......
a 30amp line, regardless of the voltage, consists of what wire size?
if you are thinking 10 awg cu or 8 awg al, you are correct.

now tell me,
how can you get 60amps off a 10 awg line?

How many lines are in a 10-3?

You were done arguing when you forgot how many conductors you have to carry 30 amps apiece, frank.

 

[bluenorth]

Hi kingmaker, I'm the op and I think I understand you. What frank doesn't get is that your not trying to carry 60amps on one line. it's 30amps on two lines which equal 60amps. My original question was very simple "30amps@240= 60amps@120". I feel confident that the answer is YES. You have two 120v hot lines from the breaker both able to carry 30amps each and the two of these 120v lines share the neutral. This is only true when you use 10-3 and not 10-2. With 10-2 there is no neutral so you are not able to get 120v off it, your stuck with 30amps and 240v. By adding a neutral your actually running two 30amp 120v lines.

 

[Guest]

Yeah bluenorth that's exactly right. Now all you've gotta get is a little breaker panel and four little inexpensive, 15 amp breakers, feed it with the tens, come out with 14 gauges to your receptacles, and you're all set.