Code restrictions on breaker placement?

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Old 10-04-06, 06:19 AM
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Code restrictions on breaker placement?

I'm trying to plan out my wiring routes & breaker placement in my main panel. I have 'X' number of circuits that I want run up my wall out of the panel & 'Y' number of circuits I want to run down the wall out of the panel. I would like to locate the breakers in the box accordingly so I don't have wires crossing each other. I want it to look very neat. I know it's usually standard practice to locate the 240 breakers towards the top, but is this required or just general practice? As long as I keep the branches balanced, can I place a 240 breaker at the bottom of the panel?

Thanks again,
Dan
 
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Old 10-04-06, 06:50 AM
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There's no reason to put any breakers any certain place in the panel. I think most electricians tend to land the largest cables first and to work from the top down.

As far as balancing the circuits in the panel, it's an exercise in futility in a residential panel because you don't use more than a few circuits at a time and large loads that matter are 240 volt anyway. The load balancing really doesn't matter to anything but the transformer that serves the house and these are generally big enough the maximum load imbalance you can generate in a residence doesn't cause problems.

Unless you are dealing with multi-wire (shared neutral) circuits you can pretty much take the circuits as they come and work side to side or top down on one side then the other, which ever is "neater" in your eyes. Don't go nuts with "neat" either. While a panel certainly doesn't need to look like spaghetti inside it's not good practice to go nuts with wire ties and such either.
 
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Old 10-04-06, 09:56 AM
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spot on target itsunclebill,

there is no way to ballance cord and plug connected loads. in comercial or residential. there is no way for the person wiring the panel to have any clue as to what will be plugged into what circuit when. (or in use at any given point in time.)

I will add that if you have any MWBCircuits then the two breakers on these must be put on oposite phases in the panel.

As a refresher, A MWBC is when two hots serve 120 volt loads, and are in the same cable with one neutral wire. since the hot wires are sharing the neutral they must be on opposing phases in the panel.
 
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Old 10-04-06, 10:38 AM
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I will add my two cents to this topic.

While it is true that the an electrician initially wiring a house does not really know what will be plugged in on each circuit, he or she can make guesses that are educated.

If you have two kitchen small appliance circuits (the minimum for the current code) they can be put on opposite legs of the service. Likewise two bathroom circuits can be placed in a similar manner.

Further, an existing home is no longer an unknown, and information is available about what is plugged in to each circuit, if time is taken to look around.

While there are no guarantees about what will be running at the same time, you can put some thought into it.

For example, I have my refrigerator (on a dedicated 20 amp circuit) and my basement freezer (also on a dedicated 20 amp circuit) on separate legs of the service. Further, I have my sump pump and gas water heater (each on individual circuits) on separate legs of the incoming service.

No, they are not typically all running at the same time, and there is no guarantee that the loads will ever be equal on each leg of the service, nut this helps. This makes even more sense considering that I can feed my panel from a generator, and that I definitely need a balanced load when using it as my power source.

So, while I don't recommend going overboard in attempting to balance the load, I don't recommend no thought given to it either.
 
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Old 10-04-06, 12:18 PM
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Well, you get in trouble here for stirring things up too much.

But, my experience is that loads in a house are almost like hooking it to a setup that can randomly turn on any one load - or several, or all at the same time. Load balancing is a consideration in large commercial and industrial installations. Other than 240 Volt loads there is just no balancing residential loads. Generators for emergency/standby use have to be sized with this in mind. EVEN IF you put a refridge, freezer,pumps, heaters - whatever, on different hot legs there is no guarantee that the automatic loads that come on at the same time won't be on the same hot leg. There is also no guarantee that the one bathroom where a blow dryer gets turned on and the microwave to heat the waffles AND the kitchen counter circuit chosen for the coffee pot won't all be on the same hot leg. Absent some kind of automatic switching this has to be considered.

All you need to do to prove this is put a recording current meter on each hot leg a residence for 24 hours after you've balanced the loads the best you think you can. I've done this more than once and the results are always the same.
 
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Old 10-04-06, 01:57 PM
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I think you missed my point in regards to my generator. I have a 5000 watt generator, feeding my panel via a 20 amp 240 volt breaker. (And before anyone complains, I have a main breaker interlock installed, preventing me from back feeding the power company.)

In my main panel I better make darn sure that my refrigerator, freezer, sump pump and water heater (loads that I definitely want to supply in the event of a power outage) are split between the two legs. If they are all on the same leg then I will definitely have a problem.
 
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