Very basic wiring questions

[GarageEnvy]

I don't know that much about electrical but some of the things I'm seeing in my house just don't seem right at all. First, I have a 200 amp service but I see 480 amps of breakers in the box. 100amps for a subpanel and 50 amps for a second subpanel in the shed. Isn't this way overloaded? I know that it's supposed to be a load test rather than simply adding them up but there are quite a few tandems. Second, I need to reroute two circuits to prepare for the relocation of the panel. Both these circuits are fed from one run of romex which goes to a junction box in the attic where it splits off. Obviously they share a neutral. Is that OK or should I run 2 separate runs of romex when rerouting. Finally, when I relocate these circuits it would be easier to feed them from the 100amp subpanel than take them back to the main panel but that would result in a total of 145 amps out of a 100amp panel. Granted 40amps are feeding this ridiculous heated shower waterfall that we never use but it's still there. The 100 amp subpanel is fed by #2 wire over about a 75' run and I'm wondering if it will support a larger subpanel.
This is not my handywork so please don't shoot the messenger.

 

[sberry]

I probably got 1000A of breakers in my 200 main, doesn't matter, not all of them are working at once.

Granted 40amps are feeding this ridiculous heated shower waterfall that we never use but it's still there.

You answer your own question, you are not using it then its irrelevant.

 

[oleguy]

load is based on load calcs not the value of all the breakers.if it was, we all would need a 600 amp panel.

 

[oleguy]

example;load calcs

 

[Norcal]

All that needs to be considered is the calculated load, the sum of the breakers installed is irrelevant as residential services rarely have much of a load........

 

[Charles (in GA)]

Second, I need to reroute two circuits to prepare for the relocation of the panel. Both these circuits are fed from one run of romex which goes to a junction box in the attic where it splits off. Obviously they share a neutral.

This is, quite simply, how wiring is done. You don't run one wire to each light or outlet, you run one wire to some point, a junction box, a receptacle, a light fixture, and from there you run to one or more others. If its a 12 gauge wire, and has a 20 amp breaker to protect it, there is no concern. In fact, when I replaced the aluminum wire in a house I used to own, that is how I wired a room, one run to a junction box, and usually four or five individual runs to receptacles on different walls of the room, it was more efficient than the daisy chain of wire from one receptacle up and over to another and again up and over to another, and so forth., one splice and then the receptacle, rather than going thru several receptacles to get to the end.

Charles

 

[tcianci]

Something that people seldom remember...the size of the breaker is to protect the circuit wiring, not an indication of how much power is being consumed or to even protect the connected device. It is entirely possible and not a hazard or overload of any type to see the total of the breakers in a panel to exceed the current capacity of the main breaker. Think of it this way... you have a 15 amp breaker to feed a circuit in your living room for instance. There are 4 outlets on that circuit, that doesn't mean that the circuit should be expected to deliver 60 amps. If you exceed the 15 amp capability of the breaker, it will trip whether it is all drawn from one outlet or split up among all 4 outlets.

 

[PassnThru]

Something that people seldom remember...the size of the breaker is to protect the circuit wiring, not an indication of how much power is being consumed or to even protect the connected device. It is entirely possible and not a hazard or overload of any type to see the total of the breakers in a panel to exceed the current capacity of the main breaker. Think of it this way... you have a 15 amp breaker to feed a circuit in your living room for instance. There are 4 outlets on that circuit, that doesn't mean that the circuit should be expected to deliver 60 amps. If you exceed the 15 amp capability of the breaker, it will trip whether it is all drawn from one outlet or split up among all 4 outlets.

I think I see what you are saying but let me clarify for my own sake - at the end of the day so to speak, the breaker will not trip until you try to draw more than 15 amps from it. So each 15 or 20 amp breaker in the box will stay live until you exceed the max for that circuit. That basically means that it is the main breaker that is your last line of defense. Because if you work at it really hard you can overload your main breaker while staying within the limits of each individual breaker. Obviously, not all the circuits in the box are at full capacity at all times - that is what allows us to have a total amperage above that of the main breaker. I have a 200A main panel in the house - I have a 100A breaker feeding the detached garage. Right now, I'm in the house - the garage is 'powered down' so all of those 100 amps are available to the house. But if I went out there and plugged every power tool I own in and fired them up an told my wife to turn up the heat and cook dinner while running the vacuum cleaner we might have a little problem.

 

[6768rogues]

If everything is wired correctly with the appropriate breaker for each wire size, don't worry about it. In the unlikely event that you repeatedly trip a breaker, you can add a circuit. You will probably never exceed 200 amps.

 

[tcianci]

I think I see what you are saying but let me clarify for my own sake - at the end of the day so to speak, the breaker will not trip until you try to draw more than 15 amps from it. So each 15 or 20 amp breaker in the box will stay live until you exceed the max for that circuit. That basically means that it is the main breaker that is your last line of defense. Because if you work at it really hard you can overload your main breaker while staying within the limits of each individual breaker. Obviously, not all the circuits in the box are at full capacity at all times - that is what allows us to have a total amperage above that of the main breaker. I have a 200A main panel in the house - I have a 100A breaker feeding the detached garage. Right now, I'm in the house - the garage is 'powered down' so all of those 100 amps are available to the house. But if I went out there and plugged every power tool I own in and fired them up an told my wife to turn up the heat and cook dinner while running the vacuum cleaner we might have a little problem.

OK you're gettin it I think, but you still referenced that 100 amps being available to the house. Kinda correct but a better way to think of it is that you have 200 amps available to the building and any other building connected to it. The decision to supply 200 amp service to your building was made on the basis of the typical combined loads being applied at any given time. You do have it correct in assuming that if you were able to turn on and run just about everything you own at the same time you may exceed the 200 amos available.

 

[GarageEnvy]

Thanks for the help. So if I have 12 gauge wire but 15 amp plugs would the breaker be sized by the wire or the outlet?

 

[comedyman809]

Thanks for the help. So if I have 12 gauge wire but 15 amp plugs would the breaker be sized by the wire or the outlet?

size by the outlet, the wire doesnt determine the size of the breaker, it just provides the correct size path for the current to flow. 15a outlet with 12 g wire depending on the the length of the run, you should be ok.