Main Panel diagram question

Old 07-11-05, 06:50 AM
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Main Panel diagram question

So I'm trying to understand the distribution of my main panel across 2 phases. The label on the panel shows that some breakers on the left side use the phase on the right (sorry if I don't have the terminology right). I was trying to find out which ones use which phase, but it's really confusing. Throw in a few twin breakers, and I have no idea which is using what. I'm curious, as I may have to move some circuits to balance out the draw.

Anyone have any insight they can share about interpreting the diagram?

Actually... I think I have it... it looks like breaker 1 & 2 share phase A. 3&4 share phase B. That sound right?
Old 07-11-05, 07:01 AM
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it looks like breaker 1 & 2 share phase A. 3&4 share phase B
In most but not all panels, this is correct.

Just curious, but why are you attempting to figure out what breakers are on what phase?
Old 07-11-05, 07:06 AM
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in talking to my neighbor, he had a similar problem with his power. We live in a new townhome (3 yrs old) and I'd not be too surprised to find out they did something on the cheap (i.e. a lesser grade e.c. that didn't pay attention to the circuit distribution). He was told the break would be quite expensive to replace and they wound up moving some of the higher draw circuits to the other phase. As I mentioned before, with all the lights and major appliances running, I was drawing 60 on one and 30 on the other. I'm hoping the main breaker is bad, but if it's not, and I have to move circuits, I'd want to know what's using what.

That and I'm anal retentive
Old 07-11-05, 09:34 AM
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It's best not to refer to the Service-Entrance Conductors as "Phase-conductors" because it's a single-phase system. A better concept is referring to the 3 SEC's that terminate on the lugs of the Service-panel as "L1", "L2" & "N".

"N" is obviousy the Neutral Service Conductor, and is the "Identified Conductor" because it is the "Grounded Conductor", being connected to Grounding Electrodes such as a metallic under-ground water-service line, and Grounding-rods driven into the earth.

The "identification" for the Neutral Service Conductor is either an un-insulated conductor, or, if insulated, the color White, and NO OTHER COLOR.

There are 3 voltage-values at the terminations of the 3 SEC's----- 220 volts L1-to- L2, 120 volts L1-to-N, & 120 volts L2-to-N. The "challenge" is to equally divide the wattage of the 120 volts loads across L1 & L2.

The Service-panel divides into 2 "Buses", L1 & L2 ,and into 2 vertical columns, with each column having a "L1"-"L2"-"L1"-"L2" "sequence" following the numerical progression. Could be, with "C#" = circuit-number----

C#1---- L1 C#2----- L1
C#3-----L2 C#4-----L2
C#5----L1 C#6-----L1
C#7----L2 C#8-----L2

Perhaps you could indentify specific "hi-wattage" 120-voltsloads and determine which breaker-bus--- L1 or L2-- - each load is connected to.Also, you will know what is connected to each breaker.

Good Luck & Enjoy the Experience!!!!!!!!!
Old 07-11-05, 12:52 PM
Join Date: Sep 2002
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60amps on one line and 30 amps on the other line is not a problem. You mention your neighbor having a problem. What was the problem that makes you think you need determine the breaker line connections? Are you experiencing a problem or you just trying balance your load. There is no reason to balance your load unless your service is a 60 amp service. If that is the case then you should be considering replacing the service.

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