15, 20, 30, 40, 50 amps

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Old 03-17-14, 12:40 AM
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15, 20, 30, 40, 50 amps

I installed an attic gable fan last year. It has been so effective for half of the house that I have decided to install another one on the other side of the house.

Master Flow 1600 CFM Power Gable Vent in Mill-PG3X at The Home Depot

As I climbed back into the attic, I realized that all of the Romex is 14 gauge. I was told to stick with 14 gauge Romex for 15 amp.

I decided to see which areas are effected by the 15 amp breaker. Once I went outside and turned OFF the 15 amp breaker, it shut down my entire second floor and garage (light and power).

Three questions:
  • Is it common that all sockets and light switches go off of one 15 amp breaker like this?
  • I was told that if I want to have the 15 amp change to 20 amp by an electrician, I would have to update all the 14 gauge Romex to 12 gauge Romex. Is this correct?
  • Is it safe to add another attic gable fan to the same Romex line (14 gauge) as the first? Each one uses 2.5 amps.
 
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Old 03-17-14, 05:28 AM
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1). Common, no. Someone did not do a proper load calculation for the circuit. I always separate lighting (usually 15 amps) from receptacles (usually) 20 amps just for load sake.
2) that is correct. Or else your wiring becomes your fuse link, since the breaker won't usually trip until it exceeds the capacity of the wiring.
3) if this is all on one 15 amp circuit, probably not. What loads do you have on this circuit. Don't forget the freezer, extra refrigerator, etc that sometimes gets put in the garage.
 
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Old 03-17-14, 06:13 AM
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How old is the house?

How many branch circuits does the house have? How many breakers are in the main panel?

At some time long ago there might have been just 3 or 4 circuits, one serving the entire upstairs.

At some time not so long ago, someone added a subcircuit to feed the garage and fed it using the upstairs circuit.

It's about time someone ran additional branch circuits and I guess that someone is you.

You will probably want at least one additional 20 amp garage circuit, plus a new 15 amp circuit to separate the existing 14 gauge garage feed onto. Also add two or three new upstairs circuits. (Use 15 amp breakers on these upstairs circuits if they are 12 gauge, as long as they are temporarily feeding existing 14 gauge wiring.)

It is suggested that additional new 20 amp circuits should be run, one for each bathroom. A not quite as good alternative is to include one new 20 amp circuit to serve all bathroom receptacles and nothing else. The work to reconfigure the bathroom wiring can be saved for a later date if no bathroom upgrades are being done now.
 

Last edited by AllanJ; 03-17-14 at 06:41 AM.
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Old 03-17-14, 11:11 AM
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I appreciate the replies Chandler and Allan.

I actually was wrong about all switches and receptacles on the same 15 amp. The switches on the second floors and some receptacles on the first floor are all together, instead of what I shared before all switches and all receptacles are on the same 15 amp. The receptacles on the second floor do have their own 20 amp.

Is there an easy way to test which receptacle socket has which amp? Right now, I have to test by turning off the breakers for each area.

Refrigerator and Electrical Stove have their own 20 amp.

I don't know what load that I have on the 15 amp circuit. It seems the only thing heavy is the garage and garden motion lights. My computer and LED is on another circuit.

So does this change whether I can add another 2.45 amp on this circuit? Lets say that I can put another one on the same circuit, does the length of romex matters?

Allan,

I don't know what you mean by how many branch of circuits. I just have one electrical box.

Here are the breakers: https://www.dropbox.com/sh/5l76cw4gd...317_094802.jpg

The house was built in 1971

Also, would you recommend a lock box on the electrical box? Do you recommend one because the original lock area was broken off.

Thank You
 
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Old 03-17-14, 04:16 PM
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One branch circuit -- One cable (not the main feed) leaving the breaker box and which may or may not have "sub-branches" up in the house. The cable is typically fed by one breaker, its own, but occasionally (a 240 volt circuit) it is fed by two breakers.

The term is sometimes confusing because once in awhile two entering cables are connected to the same breaker and some electricians consider them all as one branch circuit while others consider them as two.

Two breaker handles in the same "unit", sometimes the unit is the same size as a single breaker, mean two breakers.

A breaker panel does not need to be locked unless there is a problem with tampering.

The most easily described method to see what branch circuits the various lights and receptacles are on, although tedious to perform, is to turn off one breaker at a time and see what is dead. There exist tone generating tools that can be used to trace circuits with.
 
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Old 03-17-14, 04:27 PM
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The two fans may fight against each other. You also need to make sure there is enough makeup air for the two fans.

Depending on the current circuit load you are probably fine to add the second fan.
 
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Old 04-13-14, 09:56 PM
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Thank you for the replies. I have matched my receptacles and switches to each circuit breaker. Unfortunately, there are 3 breakers that I am not sure where they run to. Two are 20 amp and one is a 50 amp.

I actually was wrong about all switches and receptacles on the same 15 amp. The switches on the second floors and some receptacles on the first floor are all together, instead of what I shared before all switches and all receptacles are on the same 15 amp. The receptacles on the second floor do have their own 20 amp.

pcBoss, the fans will be 40 feet apart. I am not going to take a chance and add another 3 amp fan to the 15 amp circuit.
 
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Old 04-13-14, 10:07 PM
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A 50 amp circuit is commonly for an electric stove.
 
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Old 04-13-14, 10:19 PM
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The stove has a pair of 30amp and the oven has a pair of 40amp.

I did see this big weird ROUND plug out in the garage. Could that be for the 50 amp?

Also, could one of the remaining 20amp be solely for the electric water heater?
 
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Old 04-14-14, 04:18 AM
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Welders often use 50 amp circuits. Turn the breaker off and test the receptacle. Then turn it on and check it again.
 
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Old 04-14-14, 05:01 AM
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Common water heaters use a 30 amp 240 circuit.
 
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Old 04-14-14, 06:35 AM
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If you haven't identified a circuit (with a breaker pair) for the water heater and there are only 20's left then the water heater is probably connected to a 20 amp circuit. It probably draws 19 amps (4500 watt elements) during normal operation but because it cycles on for long periods it is a "continuous" as opposed to "intermittent load. Then the circuit has to be rated for 25% more amps, 24 amps requiring 10 gauge wire, round that up to 30 amps for the breaker..

Large "whole house" fans, whether in windows, attic floors, or gables, are not effective for their purpose unless several (other) windows are open in the house. The idea is that you want "cooler" outside air quickly replacing the "hotter" air inside. You keep the fan on because the first round of cooler air brought in will pick up heat from objects, furniture, and walls/floor/ceilings.
 
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