I found this on Amazon:
Something doesn't smell right with this. Anyone know if this is safe?
Something doesn't smell right with this. Anyone know if this is safe?
15/30 to 45-amp Y adapters?
- Thread starter Wayne
- Start date
ctechbob
Well-known member
Well, it would work, but you'd be limited to 15 amps on that half of your breaker panel. If you knew the box was laid out, you could make it work but I'd imagine that in a camper with 2 AC units, one would be on each 'half' of the 50 amp plug, so you might still not be able to run both of them, but you'd be able to run the one unit on the 30 amp side and then pretty much everything but the other ac unit on the 15 amp side.
I would think that if the 15 amp plug-in had a GFCI that the breaker would trip immediately, as there would be two neutral paths. If the GFCI detects a very slight delta in current between the hot and the neutral, it will trip. I have seen pedestals with and without GFCIs on the 15 amp plugin.
ctechbob
Well-known member
I'd think that would be right.
I've taken to 'cheating' when I'm at parks with 50amp plugs and it is summer. A couple times now when we've been on the 30 amp plug we'll trip the 30 amp breaker on the post if the AC is on and we're using the electric hot water somewhat hard. With both of those on it is juuuuuuuust over the point where it will eventually trip the 30 breaker on the post but not in the camper.
I'll usually pull out the 50 amp adapter at that point and ride on that 50 amp breaker.
I find it sortof odd that the 50 amp RV outlet/plug is really a 100 amp connection. No one asked me though when they came up with that. If they would beef up the neutral connection on the posts and in the camper, you'd have 100 amps to play with.
MSCH
Well-known member
AC current is sort of weird, so I don't know the answer. I do know if you run on 30A you can run the AC and maybe the microwave which is a short duration surge, but if you try to use the AC and the electric water heater its probably going to trip the breaker.
I've successfully ran the AC off a 15A wall outlet, but couldn't turn anything else on.
what they supply at the campground is basically a welder setup if its 50A. I'm not knowledgeable enough about AC wiring to do anything but replace parts with same stuff because delving off into that neutral stuff gets off into electrical weirdness I don't understand.
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I believe per NEC regulations the neutral must be rated to carry the full load of each 50 amp 120v leg. I have seen 74 amps additive between the two 120 legs in our trailer and we regularly will draw 60 amps. I have yet to see smoke coming from the wires.
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ctechbob
Well-known member
Makes me wonder why they didn't call it a 100-amp connection then.
Because at 240v the current limit is 50 amps and all 50 amp pedestals are 240v.
However, to us 120v folks, it's a 100 amp pedestal.
ctechbob
Well-known member
Good point. Are there any RV's that use 240v? I'm guessing that is super rare if they did.Because at 240v the current limit is 50 amps and all 50 amp pedestals are 240v.
However, to us 120v folks, it's a 100 amp pedestal.
You'd really hose someone up if you wired your pedestal so that the 50 amp circuit had both legs tied to the same phase. (If they had a 240v unit)
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I have heard there are, but I've never talked to anyone who had one.
You couldn't, because it would fault and trip the protection on the other end of the circuits and you would get one heck of a arc flash. It's 120v split phase so the power is 180° opposite on either leg, hence the potential of 240v between the two legs.
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ctechbob
Well-known member
I don't think it would. If you sent the same phase to either side of a water heater element, the current just wouldn't flow. That's the easiest way you could think about it. You're not using the neutral in that case, so the result would be a whole lot of nothing.
If you tried to wire both 120s to the same terminal in the plug, I promise you that you would get a LOT of sparks and arcing before the protection tripped. You would not end up with one plug terminal at 240v. As my EE friend would say, "you would let the smoke out of the wires."
ctechbob
Well-known member
Ohh, no, not that.
If you took a single phase at the box and wired it to both of the pedestal 50a breakers and sent the same phase of 120 into the RV.
Yes, you might as well practice your welding if you slam the opposite phase 120's together.
Edit - Yes, I know it wouldn't be practical since that's not how those boxes are built, but some redneck somewhere has run single phase 120 to one, almost guaranteed.
Ah, you would have 120v on both RV busses, but only 50 amps total. I'm sure you would violate some NEC rules doing that.
This is how both 30-to-50 and 15-to-50 work. They wire a single 120v leg to both hot legs of the 50 amp cord.
ctechbob
Well-known member
Yep, and if there was someone with 240v accessories they'd be SOL and wondering why things weren't working.
That's correct, because there would be no potential, so nothing.
However, if they started poking around assuming there was no power, they could easily get electrocuted. Each bus (electrical) in the RV would still have 120v to neutral and to ground.
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