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50 Amp Question


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#1 Greg & Ann

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Posted 20 March 2013 - 09:46 PM

We're heading out for our most ambitious Casita trip yet. 6 weeks on the road.

I noticed a couple of the parks only have 50 amp service. Great if you're in a 40' Sunblocker (i suppose). I bought a 50/30 adapter but wonder if plugging directly into 50 amp will sizzle anything. Thoughts????

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#2 Mark Watson

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Posted 21 March 2013 - 12:01 AM

I've run into only one park in my travels that only had 50 amp electrical service. Office had a 50 to 30 adapter cable I borrowed for a small deposit. Plugged it up between the Casita and electrical post and it worked just fine. You shouldn't have any problems using a 50 to 30 adapter cable either.

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#3 Samarai

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Posted 21 March 2013 - 03:17 AM

Adapter should should work just fine. I have used mine several times.
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#4 Ed/Helen Pensacola

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Posted 21 March 2013 - 04:28 AM

I read somewhere on one of the forums that the 50 amp is a more stable line. I have the 50/30 adapter and if avaible, always use the 50 amp plug. Make sure the breaker is off before you plug in.

#5 ArizonaEileen

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Posted 21 March 2013 - 04:48 AM

Some owners use a heavy duty surge protector, no matter whether it's 30 amp or 50 amp service.

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#6 John Croom

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Posted 21 March 2013 - 06:19 AM

Your Casita have the correct circuit breakers to the outlets. Think of it as the electric service to your home, it is the breakers in the service panel that protect your appliances.

#7 Don in OKC

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Posted 21 March 2013 - 07:21 AM

A 50 amp RV service is really two 25 amp positive sources that use a common negative. This is to serve the big RVs with two Air Conditioners where the ACs are wired inside the RV so that they are on different circuits, each one fed by a different leg of the 50 amp. Keeps the load divided inside the RV. I'm not sure if this makes sense?! Anyway, all the Casita needs is one of these 25 amp positive and the neutral to make things go.......and you're still protected.

To think of it another way, if you plug the Casita in to a 50 amp service, using a proper adapter, you're only using ONE of the two legs of electrical service available at the box.

It's works OK if used as designed. Sometimes folks may make their own adapter and cause a small fireworks display.
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#8 jwpark

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Posted 21 March 2013 - 09:55 AM

Don,
I believe you have been misinformed. The 50 amp RV service is a 120/240 split phase service. The split phase service means you have two 120 volt 50 amp poles, which gives you a total of up to 12,000 watts. The 50 amp circuit breaker is designed to open both circuits if either one of the 2 circuits exceeds 50 amps. RV power cords are typically constructed with 3 A.W.G. #6 and 1 A.W.G. #8 braided copper conductors. If each pole of a 50 amp service was only 25 amps the cable manufacturers would not need to use such large conductors; A.W.G. #10 conductors would suffice.
Something no one ever mentions is if you use a 50 to 30 amp adapter your 30 amp power cable between the adapter and the Casita converter is no longer protected from exceeding 30 amps which is what the Casita cable is rated at. The Casita converter 30 amp circuit breaker is protecting everything downstream of it. A partial short in the Casita cable between the adapter and the converter could result in the cable overheating and even an electrical fire. It's a remote possibility but not an impossible situation.

The current rating of a circuit breaker or fuse should not exceed the maximum current carrying capacity of the conductor it is feeding.

jwpark

#9 Don in OKC

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Posted 21 March 2013 - 10:46 AM

jwpark;

Your description clears up some 'fuzzy wiring' thinking that I've been carrying around several years.

Thank you, Don in OKC
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#10 Muttley

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Posted 21 March 2013 - 04:43 PM

10 years ago we bought a used stick built and an adaptor was included with it. The trailer is long gone, but we still have the adaptor. We have used it once in that time.
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#11 borderbrae

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Posted 21 March 2013 - 06:55 PM

jwpark, on the rare occasions that I've used the 50 amp outlet with my adapter I've also used my 30 amp surge protector, so it is wired, 50 amp to 30 amp adapter, 30 amp surge protector, then the electric cable from the trailer. Having the 30 amp surge protector in the line should protect my trailer, right?
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#12 Bobinyelm

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Posted 21 March 2013 - 09:55 PM

The current rating of a circuit breaker or fuse should not exceed the maximum current carrying capacity of the conductor it is feeding.

jwpark


Could you then explain why virtually EVERY power cord plugged into most home outlets (protected w/ either 15a or 20a circuit breakers, depending if the house wiring is #12 or #14ga) is 18 gauge stranded SJT not rated for more than 2.3 amps ?

Should lamp and interior extension cords all be #14 or #12 depending upon the outlet breaker capacity?

#13 buzzard

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Posted 22 March 2013 - 05:45 AM

Lamp cords, etc are out in the open, where you can / smell / hear them if they short and catch fire. Assuming you are home and awake, I suppose. I guess the same thing could be said for the shore power cord.

#14 jwpark

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Posted 22 March 2013 - 08:16 AM

Could you then explain why virtually EVERY power cord plugged into most home outlets (protected w/ either 15a or 20a circuit breakers, depending if the house wiring is #12 or #14ga) is 18 gauge stranded SJT not rated for more than 2.3 amps ?
Should lamp and interior extension cords all be #14 or #12 depending upon the outlet breaker capacity?

Bob,
In an ideal situation each device or extension cord plugged into a receptacle would have its own fuse or circuit breaker. You can buy extension cords that are fused. Most folks will not buy them because they are more expensive. Have you noticed that most all strings of xmas lights you can add strings to now have fused plugs.

The following exert is from my college text book entitled Electric Circuits and Machines by Eugene C. Lister. This is taken from the chapter Circuit-Protection and Switching Equipment. It is referring to the typical thermal operated circuit breaker such as you find in a home electrical distribution panel.

"The current carrying ability of a conductor is limited by the temperature at which the insulation may be operated safely. The operating temperature of the conductor is the sum of the temperature of the air in which the conductor is operating and the temperature rise due to the (I squared * R) [watts] loss in the conductor. A circuit-breaker that uses a thermal element for tripping depends upon the same two sources of heat for its operation and, therefore, affords a good conductor protection. Thus, when circuit-breaker sizes are properly selected, they have approximately the same response to temperature as do the conductors which they protect, and they will act to trip the circuit before dangerous overheating can occur in the conductors."

A typical house wiring circuit will have multiple receptacles connected to it. The common factor is the current carrying capacity of the conductor feeding the receptacles. There is no practical way to limit the amount of load that can be connected to an individual circuit by someone.

Let's say you have a 20 amp circuit breaker protecting a circuit consisting of #12 conductors feeding multiple receptacles. And, let's say you have a microwave, cube heater, toaster oven, hair dryer, etc. plugged into the receptacles on this one circuit and the combined load of all these devices is 30 amps. Now the power cords for the individual devices would not overheat since they are designed to carry the load of the device. However the combined loads of these devices far exceeds the current carrying capacity of the #12 feeder. To prevent exceeding the current carrying capacity of the #12 conductors, the circuit breaker trips, thus protecting the #12 conductors, not the individual devices or their power cords.

I only mentioned this in my prior post because I think folks using the unprotected 50 to 30 amp adapters should be aware that their 30 amp cable is now protected by a 50 amp circuit breaker instead of a 30 amp circuit breaker.

jwpark


#15 jwpark

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Posted 22 March 2013 - 09:00 AM

borderbrae

A Surge Protector's primary function is to protect against voltage spikes, not current. If the voltage rises to an unsafe level the spike is bled off to ground. In the case of 120 volt circuit the spike will have to reach about 330 volts before the MOV (Metal Oxide Varistor) does its thing. They will take themselves out of the circuit if the spike is of sufficient energy for the MOV to become a fire hazard. You can find lots detailed info on the internet by doing a "surge suppressor" search.

jwpark