50 amp wire size

[TXduo]

Given each hot leg of a 50 amp cord could be 6 ga for a margin on the rating, does the neutral wire need to be at least 4 or perhaps 3 gauge? Assuming a 4 wire 50 amp range pig tail is actually carrying the 50 amps across the two hots (240 volt), that pig tail neutral wire does not see the same load as an RV extension where each 120 leg may be pushing 40+ amps thus more load in the RV neutral wire? So, would this typical pig tail
HDX 6 ft. 6/8 4-Wire Range Extension Cord-HD#575-052 - The Home Depot
be INAPPROPRIATE to use in wiring up an auto former as the neutral wire is only 8 gauge? To reach ventilation for a Hughes autoformer installation, I need a little longer pig tail than the Hughes installation kit provides, so I think I need to fabricate my own and thus want to verify safe stranded cooper wire sizes, or if this range pig tail is really okay to use.

[hypoxia]

That cord has 6 ga for the hots and 8 ga for the neutral and ground. You need 6 ga for the neutral IMHO, thus it would not be recommended.

If you look at a 50A RV cord it is normally 6/3-8/1.

RV FLEX50A - Super flexible 50A cords | Technology Research, LLC

[twinboat]

The neutral only carrys the difference between each leg.

Example, 30 amps on L1, 20 amps on L2. Neutral is carrying 10 amps.

So the max amps a neutral will ever carry is 50 amps, if one leg is carrying 50 amps and the other is carrying 0 amps.

240 volt dryers and ranges use 240 volts so the neutral only carrys the 120 volt timer or clock current.

Some more explanation.
https://www.rvtechmag.com/electrical/chapter3.php

[TXduo]

Okay. Got it. With a split phase, neutral sees only the difference between the legs, not the sum.

[A32Deuce]

Same size difference on the 12 volt side. You can use one size smaller gauge for grounds.

[Sbrownstein]

Originally Posted by A32Deuce

Same size difference on the 12 volt side. You can use one size smaller gauge for grounds.

Definitely not the case for 12 V DC. The same current is carried by the "ground" that is carried by the "hot." Matched wire sizes required and the voltage drop on 12 volts is far more serious so conductor size is always a factor depending on run length.

[Steve Ownby]

Originally Posted by TXduo

Given each hot leg of a 50 amp cord could be 6 ga for a margin on the rating, does the neutral wire need to be at least 4 or perhaps 3 gauge? Assuming a 4 wire 50 amp range pig tail is actually carrying the 50 amps across the two hots (240 volt), that pig tail neutral wire does not see the same load as an RV extension where each 120 leg may be pushing 40+ amps thus more load in the RV neutral wire? So, would this typical pig tail

HDX 6 ft. 6/8 4-Wire Range Extension Cord-HD#575-052 - The Home Depot

be INAPPROPRIATE to use in wiring up an auto former as the neutral wire is only 8 gauge? To reach ventilation for a Hughes autoformer installation, I need a little longer pig tail than the Hughes installation kit provides, so I think I need to fabricate my own and thus want to verify safe stranded cooper wire sizes, or if this range pig tail is really okay to use.

If wired correctly, the neutral wire only carries the difference between the split phase legs. If one leg is carrying 40 amps and the other leg 10 amps then the neutral is carrying 30 amps. If both were running at full rated output of 50 amps each then the neutral wire would be carrying zero amps. Conversely, if one leg was carrying 50 amps and the other leg was zero then the neutral would be carrying the full rated 50 amps.

[twinboat]

Originally Posted by A32Deuce

Same size difference on the 12 volt side. You can use one size smaller gauge for grounds.

Not sure I understand what your saying.

In a 12 volt system there are only 2 wires used. If one is smaller, it will cause a drop in voltage and overheat, if you draw what the positive wire is rated for.

[A32Deuce]

You are using current to do something so there is a loss.

[A32Deuce]

Battery wiring is different. They should be the same size.

[TXduo]

This topic has made me a firm believer in always should check the pedestal with a meter before plugging in. I remember one RV park where I plugged into their 50 amp box and thought all was good (voltages on L1 and L2 looked normal on the inside Aladin) but a couple days later when doing laundry, the 240V dryer would not run. Turns out pedestal had both legs powered from same leg! (BTW, the park general maintenance guy first said all was okay as he saw 120 on each leg to neutral. I asked him to show me 240V and he couldn't so he finally called in the park electrician to explain it to me that my dryer must be broke. Electrician said said "oops" and traced problem back to distribution panel. They had had a lightening strike a few days earlier and had to replace/rewire several things and I guess got several main distribution breakers inserted wrong somehow...) So no split phase and thus I see now that the neutral wire could have been theoretically overloaded returning the sum of the current... 2 A/C's, microwave, washer, hot water, etc drawing on effectively parallel legs that were not split phase.

Anyway, FWIW...