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50A rigs and wire sizing

RVnRobin
Explorer
Explorer
A post yesterday about a burnt neutral wire got me to wondering...
If;
A 50A rig has all 120v appliances and loads,
A 120v 10A load will measure the same amperage draw on both the hot side and the neutral side,
A properly wired 50A service will measure 240v from L1 to L2,
And L1 and L2 will each measure 120v to neutral,
50A load max on L1 and 50A max on L2,
The neutral is shared with both,
The load amps from each of the hot lines are additive on the neutral,
Potential load on the neutral wire could max out at 100A.

Question;
Why isn't the neutral wire at least a #2 as per the wire sizing charts?
Wouldn't cords need to be constructed with two #6 for each of the hot lines, one #2 for the neutral, and then the ground?
Is this why we see neutrals frequently have heat damage?

I'm not an electrician. I know rarely both L1 and L2 would run at max. But the amperage charts seem to be pretty clear about what "code" requires.
So much to experience, so little time.
18 REPLIES 18

tvman44
Explorer
Explorer
The 2 previous posters have it right. ๐Ÿ™‚
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SolidAxleDurang
Explorer
Explorer
RVnRobin wrote:
..
The load amps from each of the hot lines are additive on the neutral,


Incorrect.

The neutral always holds the delta between L1 and L2.

L1 is supporting 40 amps.
L2 is supporting 10 amps.
N would then be supporting 30 amps.

L1 is supporting 50 amps.
L2 is supporting NOTHING.
N would be supporting 50 amps.

L1 is supporting 50 amps.
L2 is supporting 50 amps.
N would be supporting NOTHING.
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Roadpilot
Explorer
Explorer
If all the load were on one side the neutral current would equal the hot side current. If you then add any load to the other hot lead the neutral current goes down accordingly since that load is of the opposite phase of the other.
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rhochnadel
Explorer
Explorer
L1 and L2 are on different phases and the neutral load from the two is zero or very small.
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