I hope someone can clear up something I saw while camping this weekend. A gentleman came in with a TT and plugged a 50 AMP to 30 AMP reducer into the pedestal, then plugged his 30 AMP TT into the reducer. Had the 30 AMP on the pedestal not been working, I could have understood it, however I know it was working because I had left the spot he was put in about 1 hour before to the spot next to it. I am wondering if anyone knows of a reason to do this and if there is a advantage. Thanks for everyones input in advance.
Todd
Todd, Kris (wife), Jarrett (7 yo son), Emily (4 yo daughter), and usually Jim and Dee (the in-laws.)
A lot of times, the 30 amp is worn. The 50's seem to get less use, therefore less worn. A worn out plug can burn up the end of your cord in a heart beat so some people go straight to the 50amp
When a reducer is used, the 30 amp system in the coach has access to 50 amps, which is the point the circuit breaker on the post is designed to trip. That could cause the plugs and cord to get warmer than they should, and possibly cause a fire or other overheating problems in the coach. Hopefully, the circuit breaker or breakers in the coach would prevent this excessive current flow.
The advantage is avoiding the lower voltage from drawing too much current thru a worn plug. Low voltage can cause all kinds of problems with electric motors, like the one in your air conditioning. JMHO
Holiday Rambler Navigator DP, Mustang Convertible, and Honda VT1100C Shadow.
Ok-I need to ask - never having plugged into 50 Amp service, are there actually two 25 Amp breakers hooked together? Being as the two 25 Amp lines can be in phase or out of phase, does the NEC require any particular phase relationship between the two feeds?
Just curious,
Joe
"Ok-I need to ask - never having plugged into 50 Amp service, are there actually two 25 Amp breakers hooked together? "
There are two 50 amp breakers hooked together. A properly wired 50 amp service will supply up to 12,000 Watts. (P=V * I, so 120V * 50A * 2 or 240V * 50A) In a properly wired 50A service, there will be 240V between the two hots. While it's a subject of semantics around here, in your lingo, the two hots would be "out of phase" with respect to the neutral. The proper term used by the electricians, I believe, is "split phase". This needs to be the case so that the neutral conductor will carry the difference current between the two hots. If they were "in phase", then the neutral would carry the sum of the two hots, and would require a neutral wire that can carry more current than either hot. With typical lengths, 50A service is 3-6 gauge wires (2 hots and 1 neutral) and one ground, usually 8 gauge.
A 30 amp service receptacle can supply up to 3,600 W (120V * 30A).
~Rick
2005 Georgie Boy 3625 DS on a Workhorse W-22 (Class A)
Rick, Gail, 1 girl (12-Angel), 1 girl (7), 2 boys (8 & 5), 1 plump Golden Retriever.
2001 Honda Odyssey with Demco Aluminator tow bar & tow plate, SMI Silent Partner brake controller.
Rick - your explanation was beautiful. If I understand correctly, each hot leg can supply 50 Amps, and as long as the two hots are out of phase (allow me this nomenclature), the receptacle can offer 12kw. I wonder why it's not called 100Amp service, as each leg offers 50 Amps? Normal house wiring has two 100Amp feeds, and it's called 200 Amp service, no?
Joe
I believe your posts on this issue are exact copies of some posts I made way back when and some good folks here talked me through it all! LOL
I believe that what you say about the 2-100 amp breakers being called 200 Amp service was an older convention. I believe what was explained to me is that a new home with 200A service will have 2-200 amp breakers. By the old terminology, it would be 400A, but it's called 200A.
But I know the more technically savvy electricians here can give you a more detailed explanation.
nbounder wrote: Rick - your explanation was beautiful. If I understand correctly, each hot leg can supply 50 Amps, and as long as the two hots are out of phase (allow me this nomenclature), the receptacle can offer 12kw. I wonder why it's not called 100Amp service, as each leg offers 50 Amps? Normal house wiring has two 100Amp feeds, and it's called 200 Amp service, no?
Joe
- Each "leg" can indeed supply 50 amps, but at 120 vac per side.
- They are indeed out of phase, so it's not called a "double 120vac circuit" or anything like that - It's simply a 240 VAC circuit fused at 50 amps - It's a 240 vac circuit that just happens to consist of two "out of phase" 120 vac circuits. Let's try saying it this way...If you run the circuit as a 240 vac circuit and exceed 50 amps the circuit shuts down.
- Most RV's don't utilize 240 vac circuits, but they could
- The circuit is just like your home's incoming power feed except for the size of the main breaker - just as in your home, you "could" run all 120 vac appliances - if you did and you had a 200 amp main fuse box, (remember that it's a 240 vac panel) you could "theoretically" run 400 amps of 120 vac appliances.
When we had a 30 amp coach, we always used the 50 amp outlet if available.
following the plans of somebody here, I built a 50 amp male plug with two 30 amp female outlets. he claimed that one side of the 50 amp is sometimes "better" than the other, probably because original campground was 30 amp and rewired? So can check which side of the 50 is better. also, as stated, 30s get worn.
bumpy
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