FR 50 to 30 amp warning |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Topic: FR 50 to 30 amp warning Posted: 18 Sep 2018 at 5:42pm |
mcarter, its not about how many watts of load.
Its about the amps you can see in your conductors under fault conditions. The circuit the dog bone is connected to has overcurrent protection rated at 50A. The dog bone is required to use 6 AWG conductors which can handle 50A. The cord you connect into he conductors and the conductors between the receptacle on your trailer and the trailer power center are not rated for 50A, only for 30. Hence these conductors can overheat and start a fire in the event of a fault current which exceeds 30A but is less than the 50A that can trip the 50A service breaker.
Hope that makes sense. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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mcarter
podders Helping podders - pHp Joined: 07 Apr 2016 Location: Greenbrier, TN Online Status: Offline Posts: 3419 |
Posted: 18 Sep 2018 at 5:26pm |
So - you have a pedestal with a 50A and a 30A outlet, you plug into the 30A and you get 120V, 30A capability at 3600 watts. You get out your dogbone and plug your 30A connector into the 50A connector which has 2 independent 120Vs and about 12000 watts capability, however the dogbone only gives one 120V circuit and how is it that you can exceed the 3600 watt capability of your 30A service? I don't think you can.
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Mike Carter
2015 178 " I had the right to remain silent, I just didn't have the ability." |
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StephenH
podders Helping podders - pHp Joined: 29 Nov 2015 Location: Wake Forest, NC Online Status: Offline Posts: 6289 |
Posted: 18 Sep 2018 at 5:24pm |
I did not need to find the breaker since we did not have any issues. I don't think we will be returning to that particular RV park again. You don't need to look all through the RV park, just ask at the office.
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StephenH
Happy is the man that findeth wisdom,... ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
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lgblau
Senior Member Joined: 09 Feb 2018 Location: Arizona Online Status: Offline Posts: 140 |
Posted: 18 Sep 2018 at 5:04pm |
StephanH....Are you serious. Like I’m going to look all over the rv park to find a buliding that has the breaker for my outlet.
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Leonard🌵
2017/179 2017 Ram 1500 |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Sep 2018 at 4:12pm |
No, it is not the same thing as for example a table lamp that uses 16 gauge wire. The conductors between the receptacle on the trailer and the panel are not temporary wiring like a table lamp, they are permanent, and as such the NEC applies. The NEC is intended to keep those conductors from overheating and causing a fire. The breaker in the trailer panel does not protect those conductors as it is downstream from the source feeding the conductors. As I said, there are plenty of electrical faults which are sufficiently resistive that they do not trip the breaker. Not only can I imagine them, I've seen them. So, it is your option to use one of the dog bones but know that there is risk involved in doing that. if you don't believe me, that's fine, go read the warning label underneath your trailer receptacle. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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adventurelust
Newbie Joined: 16 May 2017 Location: Ventura, CA Online Status: Offline Posts: 20 |
Posted: 18 Sep 2018 at 3:57pm |
I see it all the time, where a connection is marginal, but is not enough current flow to cause the circuit breaker to trip, or a fuse to blow. It's kind of like a high impedance heater coil, but without the controlled resistance. True we use lamp cord all the time for appliances, but if you look at something with allot of wattage, the cord is usually sized for the load. JMHO
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"Eighty percent of success is showing up" Woody Allen
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Keith-N-Dar
podders Helping podders - pHp Joined: 03 Apr 2011 Location: Mayville, WI Online Status: Offline Posts: 1447 |
Posted: 18 Sep 2018 at 3:26pm |
The Pod is protected by a main breaker. The power cord draw is limited to the amperage of that breaker, unless there is dmage to the cord. A sudden defect causing a short circuit would cause sufficient draw that would trip the 50 amp breaker on the pedestal. I can't imagine any situation that would cause the cord to create heat and catch fire. This is like plugging a device with a number 16 power cord into a twenty amp outlet. The wire is much to small to carry 20 amps but we do it all the time. The
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Keith-N-Dar
Boris & Betty (Boston Terriers) 2011 R-Pod 177 2010 Ford F-150 |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Sep 2018 at 2:41pm |
The 2017 NEC requires disconnecting means at the pedestal. Could be a switch or a circuit breaker. I don't know how long ago that became a requirement though.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Sep 2018 at 2:31pm |
The UL listing for the dog bone only addresses the dog bone. It is sure enough safe to connect to 50A.
The NRTL is putting up an SEP (somebody else's problem) field around the dog bone. They were asked to evaluate and list a product to a standard and they did. If you've ever read the Hitchhiker's Guide to the Galaxy you'll know what an SEP field is. If you haven't read it, you should Besides, the manufacturer is their customer, not the consumer. Now its a little different for the manufacturer. They can't knowingly sell something to a consumer that creates an unsafe condition in normal use and hide behind the argument that its listed. Well they can try but they wouldn't be in business for very long that way. Internal memos from their engineers to management are discoverable and can lead to juries handing out huge product liability settlements.... That's why I'm curious to see what the instructions that come with the dog bone say. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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StephenH
podders Helping podders - pHp Joined: 29 Nov 2015 Location: Wake Forest, NC Online Status: Offline Posts: 6289 |
Posted: 18 Sep 2018 at 2:11pm |
It is possible that the breaker for that circuit is in a building. It isn't as if the RV park would have no breakers. We stayed in one like that and were told where to find the breaker if needed.
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StephenH
Happy is the man that findeth wisdom,... ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
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