50 amp sore cord question

[Kpackpackkelley]

I want to make my 50 amp shore cord out of 6/4 soow or stw cord. When I look at the amp ratings on these two cords its 45 amps.
When I looked at a 50 amp shore cord with moulded plugs at the rv supply its 6/3 + 8-1 its stw cord but it's rated for 50 amps. Does anyone know why it's rated 5 more amps ?
Thanks

[AllegroD]

What kind of heat is produced, with this cord rating, while coiled?

[bshpilot]

wa8yxm wrote:
Most wire ratings are for wire IN A WALL or Conduit,, The RV cord is rated for wire in air,, Better heat dissipation.

while i tend to agree w/ you, on external cords/extensions the jacket type also plays into the rating.

[wa8yxm]

Most wire ratings are for wire IN A WALL or Conduit,, The RV cord is rated for wire in air,, Better heat dissipation.

[Kpackpackkelley]

smkettner wrote:
Are you really going to be pulling a full 50 amps near continuous? How long is the cord?
Maybe you need #4.... I think the 45 amp rating will be a non-issue.

I believe 45 is plenty just wondering about the rating.

[time2roll]

Are you really going to be pulling a full 50 amps near continuous? How long is the cord?
Maybe you need #4.... I think the 45 amp rating will be a non-issue.

[bshpilot]

Kpackpackkelley wrote:
I've already got about thirty ft of 6/4 soow cord but it's rated at 45 amps. Just wondering why the stw rv supply 6/3 + 8/1 is rated 50 amp maybe less copper in the jacket because of smaller gd.
6/4 stw and soow are rated at 45 amps.

ill have to check the jacket stamping to confirm.

I've never seen more than 30A draw per leg. My wife can trip the breaker (on 30a shore power) when we have both AC's, her blow dryer and the coffee maker on.

[Kpackpackkelley]

I've already got about thirty ft of 6/4 soow cord but it's rated at 45 amps. Just wondering why the stw rv supply 6/3 + 8/1 is rated 50 amp maybe less copper in the jacket because of smaller gd.
6/4 stw and soow are rated at 45 amps.

[bshpilot]

I built a 50A (75ft) extension cord using 6/3 8/1 and found it in an SOO jacket rated for 600v & 50 (or more iirc) amps...it was almost as expensive as my basement electric cooler 😮

I could have bought TWO 30ft extension cords from camping world cheaper but i didn't want the connections laying in wet grass at my in-laws

[westend]

I think we have the amperage issue covered but I'll post a caveat about making a 50 amp cord. Unless you have some special need to make your own cord (distances involved, unique connectors, etc.), buying an off-the-shelf cord is going to be less expensive. I went through this exercise a couple of years ago and by the time you pay for the correct wire and connectors, a retail cord is less cost. I got lucky and found a Marinco cord at Camping World on the clearance table. It cost about half of what I was going to pay just for the wire.

[Kpackpackkelley]

Thank yawl for your help.

[ken_white]

Kpackpackkelley wrote:
Thank you ken . I understand you i just want to make sure if i build a shore power cord the neutral can carry 50 amps not 45.

Kpack, most service centers have a somewhat balanced load center so the current in the neutral is always less than 50 amps, that is why a smaller conductor is used.

The wire part of the cable gets hot but will not melt unless very high currents, called fusing currents, are present.

The insulation is what melts at currents higher than rated, but less than fusing.

So, build your extension cord and load it heavily and take some measurements or just see how hot it feels.

Quality plugs/receptacles and the cable selected should work fine as long as the cable length is not excessive.

If you plan on making a very long cable, then you may want to drop down a wire gauge or two.

[tvman44]

I too have amp meters in my 50 amp service and I almost never exceed 25 amps per leg. As for the neutral if the 50 amp power source is properly wired the neutral only carries the difference between the 2 legs due to phase cancellation, so no problem there. 🙂

[Kpackpackkelley]

Thank you ken . I understand you i just want to make sure if i build a shore power cord the neutral can carry 50 amps not 45.

[ken_white]

Kpackpackkelley wrote:

Big Katuna wrote:
You don't need 4 #6. The 4th green wire can be #10 and they DO make a product like that.

I have amp meters on my RV and you could really get by on an extension cord with 4 #8s. I have rarely seen a 30a draw on the front leg and the second leg just runs the rear AC.

If this is for your primary cord then by all means use the 3-#6, 1-#10 wire.

I'm just learning all these amp ratings.
I understand you would very rarely have even 25 amps a leg but you have the neutral being shared so it would have to be able to carry both 25 amps which would be 50 amps since its 120 volt only from a generator that's what I'm working on . I believe the soow cord is alright on shore power but from a 7 k gen you have 2 legs of 120 volt not 120/240. I'm just trying to figure all these amp ratings for different size and number of conductors plus which voltage it is rated for.

In a 50 amp RV service cable, the neutral will always carry 50 amps or less.

It will never carry more than 50 amps.

The reason is both hot phases are 180 degrees out of phase so the neutral always carries the difference between the 2 phases.