RV power is two 25 amp 120 volt circuits. RV cables could be 10 gauge for L1 and L2, 6 gauge for the neutral (return), and 8 gauge for the ground. It would make for a less expensive and easier to deal with cable. The problem, for all of this, is building codes. They content that if looks like a duck (a 240 volt circuit), it must be a duck. This is a huge dis-service to the RV community.
No, a 50-amp RV shore power feed consists of two 50-amp, 120-volt split-phase or 3-phase circuits (180 or 120 degrees out of phase with each other, so 240-volts or 208-volts leg-to-leg) which requires 6-gauge conductors for L1 and L2, plus a 6-gauge conductor for the neutral, plus an 8-gauge conductor for the EGC (ground). It supplies either 208-volts (3-phase Wye) or 240-volts (split-phase) to a NEMA 14-50 Receptacle in order to stop additive neutral currents from forming which could exceed 50-amps if L1 and L2 were connected to the same pole or phase.
You state that while using a 50ty amp, 240 volt, RV cable that the ground wire only needs to be 8 Guage. And the neutral needs to be the same size as the hot wires. However using the diagram that you supplied, you are splitting the 240 volts and you are using the 110V to ground the same as the 110V neutral and it too (the ground) may carry the same current as the neutral. So what am I missing?
The ground conductor is never supposed to carry any load current, so it won’t be heated during normal use. But when there’s a short circuit it only needs to carry a few hundred amperes of fault current for less than 100 milliseconds to trip the circuit breaker. I’ve done this demonstration on my lab bench dozens of times with videos and high rate data logging of the tripping event. I could publish an article on it if you all would like…
My trailer uses only a 30A cable but I value the fact that it is heavy duty and am willing to put up with a bit of extra weight and a larger diameter within reason. It has seen a lot of use over the years and my concern would be that a lesser cord might not hold up as well. It would be good to see the studies that were used to set the current code standards to see what data they are based on. As one might expect, one could probably pay more and get a thinner and lighter cable made from more expensive materials that met the same standards. It would be interesting to know how much difference it would make in diameter and weight for high-performance 30A and 50A RV cable of the same length.
Mike: While at the International Airstream Rally this past week SmartPlug was there and had a new 50amp cable, as light and thin as the 30amp. I made my own and look like the thickness you showed in todays post. Your thoughts on this new "thin cable". Thank You, Bud Roberts
I’m investigating if SJOOW (Junior SO portable cord rated for 300 volts instead of 600 volts) is allowed by code for RV power. But I’ve not seen any code exception for this application, so I’m not sure it’s allowed by code. What exactly does your “thin cable” have marked on the side? And please send any pictures to mike@noshockzone.org
Mike: I did not buy the cable from SmartPlug. My cables, I made with Smartplug connections are what I consider "true" RV cables. One is the large grey one which came with the trailer and the other is the newer black one from Airstream I cut down to 15' for a lighter cable used most of the time. Unfortunately, I did not look closely at the Smart Plug cable they were promoting. They are also coming out with one that hangs at 90 degrees from the side of the trailer, in the spring.
RV power is two 25 amp 120 volt circuits. RV cables could be 10 gauge for L1 and L2, 6 gauge for the neutral (return), and 8 gauge for the ground. It would make for a less expensive and easier to deal with cable. The problem, for all of this, is building codes. They content that if looks like a duck (a 240 volt circuit), it must be a duck. This is a huge dis-service to the RV community.
No, a 50-amp RV shore power feed consists of two 50-amp, 120-volt split-phase or 3-phase circuits (180 or 120 degrees out of phase with each other, so 240-volts or 208-volts leg-to-leg) which requires 6-gauge conductors for L1 and L2, plus a 6-gauge conductor for the neutral, plus an 8-gauge conductor for the EGC (ground). It supplies either 208-volts (3-phase Wye) or 240-volts (split-phase) to a NEMA 14-50 Receptacle in order to stop additive neutral currents from forming which could exceed 50-amps if L1 and L2 were connected to the same pole or phase.
Please read this article for an in-depth tutorial on how it works. https://open.substack.com/pub/rvelectricity/p/pedestal-power-principles-part-2
You state that while using a 50ty amp, 240 volt, RV cable that the ground wire only needs to be 8 Guage. And the neutral needs to be the same size as the hot wires. However using the diagram that you supplied, you are splitting the 240 volts and you are using the 110V to ground the same as the 110V neutral and it too (the ground) may carry the same current as the neutral. So what am I missing?
The ground conductor is never supposed to carry any load current, so it won’t be heated during normal use. But when there’s a short circuit it only needs to carry a few hundred amperes of fault current for less than 100 milliseconds to trip the circuit breaker. I’ve done this demonstration on my lab bench dozens of times with videos and high rate data logging of the tripping event. I could publish an article on it if you all would like…
My trailer uses only a 30A cable but I value the fact that it is heavy duty and am willing to put up with a bit of extra weight and a larger diameter within reason. It has seen a lot of use over the years and my concern would be that a lesser cord might not hold up as well. It would be good to see the studies that were used to set the current code standards to see what data they are based on. As one might expect, one could probably pay more and get a thinner and lighter cable made from more expensive materials that met the same standards. It would be interesting to know how much difference it would make in diameter and weight for high-performance 30A and 50A RV cable of the same length.
Mike: While at the International Airstream Rally this past week SmartPlug was there and had a new 50amp cable, as light and thin as the 30amp. I made my own and look like the thickness you showed in todays post. Your thoughts on this new "thin cable". Thank You, Bud Roberts
I’m investigating if SJOOW (Junior SO portable cord rated for 300 volts instead of 600 volts) is allowed by code for RV power. But I’ve not seen any code exception for this application, so I’m not sure it’s allowed by code. What exactly does your “thin cable” have marked on the side? And please send any pictures to mike@noshockzone.org
Mike: I did not buy the cable from SmartPlug. My cables, I made with Smartplug connections are what I consider "true" RV cables. One is the large grey one which came with the trailer and the other is the newer black one from Airstream I cut down to 15' for a lighter cable used most of the time. Unfortunately, I did not look closely at the Smart Plug cable they were promoting. They are also coming out with one that hangs at 90 degrees from the side of the trailer, in the spring.
I would like to see what the newer black “skinny” cable is from Airstream. Please send a picture if you can…