another electrical question....

[PoopyTeaBags]

i am running a 30a single pole breaker on a 10 guage wire to a junction box... now from this junction box im going to put 3 15a plugs... my question is since the plugs will not be carring anything close to 20a can i then use 12g wire for all the plugs and then tie them all into the 10g wire in the junction box... ?

 

[Panama Red]

12g is fine for 15A runs even if it's a bit of overkill.

But if I understand correctly, you're going to do 3 runs to the junction box, tie them all together and let the 30A breaker back at the main panel be your protection?

No, no, no. Any one of those 15A's can start drawing more current than the receptacle or the 12g can handle and start cooking long before that 30A will trip.

Spring for a small sub-panel instead of a junction box and put three 15A breakers in it.

 

[solarz]

Panama, in this situation, how is it possible to run 3 x 15amp circuits off of a single 30amp circuit? Maybe i'm understanding it wrong.

solarz

 

[PoopyTeaBags]

really panama? so what your saying is sense they are 15a plugs and there all tied together at the junction box then there a chance for all the power to run through one plug and fry it? is that what your saying?

then how would you piggy back plugs with out them over loading??

right now what i got is a 30a single pole ran to a junction box and then connected 3 other 10g wires to 15a plugs....

so that wont work??? is there bigger plugs then 20a 120 plugs? im confused now... i was always told you can piggy back plugs... or sense they are all tied at one focal point its not considered piggy backing? sigh.... im 45 min away from home depot this is getting tireing....

 

[Panama Red]

If you get an overload/short condition on any one of them, the 15A receptacles and the 12g wire will fry before the 30A breaker trips.

You can piggy back outlets as long as your breaker is rated the same (15A) not higher.

Basic rule of thumb: The breaker controlling the circuit should be the weakest link in the chain.

Go to Home Depot, get a 15A breaker to replace the 30. And pick up one of these while you're there so I can stop worrying.

 

[Tilt]

Hey p.t.b., P red is right you can put 15 or 20 amp rated receptacles on a 20 amp breaker. In commercial applications we hardly ever go above 9 receptacles per circuit. What equipment are you running look and see what current it draws on a nameplate. You might be fine at 20 amps

 

[GeorgeSmiley]

The U.S. National Electrical Code Article 220.3 (B) (9) has guidelines for calculating general 120 volt dwelling-unit receptacle circuits as having a load of 180 volt-amps per receptacle.

Because a normal circuit breaker can only be loaded to 80 percent of trip rating, then 0.80 X 15 = 12 Amps. 12 Amps X 120 volts = 1440 Volt-Amps per 15-Amp circuit. 1440 VA / 180 VA per receptacle = 8 duplex receptacles per circuit allowed.

For a 20-Amp circuit, you are allowed (.8 x 20 X 120)/ 180 = up to 10 duplex receptacles per circuit.

Found this a while back when wiring my panel. So yeah as Tilt said what's your load gonna be?

Smiley

 

[PoopyTeaBags]

thanks guys i went with a junction box and 3 20a plugs on 10g wire and am makeing sure i dont over load the individual plug/ lines.... thanks again for the input

 

[rives]

thanks guys i went with a junction box and 3 20a plugs on 10g wire and am makeing sure i dont over load the individual plug/ lines.... thanks again for the input

Did you change the breaker out to a 20 amp unit?

 

[Marshall]

In simple terms, a breaker protects everything downstream, wiring, outlets. The issue is not your projected or expected loads. The issue is when shit goes wrong, wire gets shorted, etc.

Personally I have used 15A outlets on 20A circuits. It was a risk but a calculated risk as I felt like if the circuit got overloaded, the outlets could handle it as I used the side screws, not the stab ins. I felt like the metal plates could handle the higher amp and the outlet was not actually providing 20 amps. If something shorted or went bad that was plugged into the outlet, I may have been in trouble

To be 100% safe your breaker should never be rated higher than your wire or outlets

 

[Marshall]

Panama, in this situation, how is it possible to run 3 x 15amp circuits off of a single 30amp circuit? Maybe i'm understanding it wrong.

solarz

The circuit is rated 30A MAX. each outlet is rated 15A MAX. That doesnt mean each outlet can actually use 15A at once. In theory you could wire 100 15A outlets.

To provide a visual, take a 1" water pipe and tee it off to 3 3/4" pipes. The 1" pipe can not provide enough water to flow all 3 pipes at once at max, but 1-2 pipes at once could run at max.

hope that makes sense

 

[dansbuds]

basicly what it comes down to is change your 30 amp breaker to a 20 amp because your 12 gauge wire is good for 20 amps . then if you overload the circuit nothing will burn up & worse case is you'd have to run another 20 amp line for more power .but doubt you'll need it unless you have alot of equipment going at once.