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Old 09-15-2013, 05:18 PM   #1
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2 30 amp plugs to a 50 question

Hello all,

Apologies if this has been covered but I could not find it. At our tailgating we share a pair of boxes with another rig. One box is a 50 and it seems we both want it. We've split so far this season. The other box has 2 30 plugs with individual breakers and 1 20 with a breaker. I ended up using one of the 30s with my 30 to 50 cord. Some one came up and offered the use of his "2-30s to a 50" cord and says it will give me everything I would get from the 50. Since I'm new to this, I said thanks but stayed with the 30.

Did a search after I got home and found this
Amazon.com: Conntek RV 50-Amp Power Optimizer (2) RV 30-Amp Plug to 50-Amp 125/250-Volt 14-50R Female Connector: Sports & Outdoors

I own a 2013 Berkshire and, as you can tell, I'm not electric savvy. Will using this give me all the power that a 50 will and will I be safe from any potential damage to my system?

Thanks in advance,
JJ
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Old 09-15-2013, 05:32 PM   #2
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Originally Posted by JJvike View Post
Will using this give me all the power that a 50 will and will I be safe from any potential damage to my system?

Thanks in advance,
JJ
It can't give you ALL the power that a 50 amp service is capable of. A 50 amp split phase service is capable of giving you 50 amps per leg...or two lines/legs for a total of 100 amps of potential power.

Your 50 amp RV, in simple terms, utilizes two legs of incoming electricity, which are 50 amps per leg...or 100 amps total. It's very doubtful though you are using this many amps....but you do have the means if necessary.

Using the cord adapter you are asking about, the best you can get is 30 amps per leg.... on two legs/lines for a total of 60 amps of power.

As long as you don't exceed 30 amps of usage per leg, I would think you would be OK.

We have some great electricians here, and they should read this to confirm.

Here is a link that may help in your understanding of a 50 amp service:

http://www.rvcruzer.com/electrical/chapter3.php

When you use the adapter you are currently using, to plug your 50 amp RV into just one 30 amp outlet, you are limiting your total electrical usage to only 30 amps total...that comes from one line at the outlet, then is shared across both sides of your RV.
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Old 09-15-2013, 05:39 PM   #3
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Good question! The answers are "no" and "maybe not".

On a 50-amp service you have 2*50= 100 amps available. With two 30's, you have 60 amps available. Not technically the same, but maybe close enough for your purposes.

The problem is that it may not be safe. As you know. your power cord has wire rated for 50 amps. So how can you put 100 amps thru the shared neutral? The answer is you can't (safely). It works because the two hot sides of the 50-amp service are opposite phase, so in the neutral, the currents actually subtract, giving you zero amps in the neutral wire if you are pulling 50 amps out of each side.

How can you make this work for the "cheater" box you found? Using a volt meter, check to see of you have 240v between the two hot terminals present in the two 30-amp outlets.

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Don't be tricked if the outlets are upside down from this picture. You will either read ~240v or you will read 0v. (If you read 120v, either you're doing it wrong or the outlets are wired incorrectly.)

If you read, 240, you have no worries and can use the cheater with no problems.
If you read 0, both outlets are delivering the same phase and it will be up to you to ensure that you don't go over 50 amps total for the two legs.
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Old 09-15-2013, 07:11 PM   #4
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I found a 15 amp and 30 amp to a 50 amp adapter. Checked the 15 amp side and corrected my electrical panel so the smaller bedroom ac is on the 15 amp leg. It is a pain to check and set up, but, I don't have to worry about an over loaded neutral wire and most camp grounds have the 30 and 15 amp outlets together with each on its own breaker.
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Old 09-15-2013, 07:56 PM   #5
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The adapter you found will work fine. You don't need to be confused by all the logistics of the 50amp electrical system . The most that would possibly happen, would be a tripped circuit on the pedestal if you happen to draw more juice than the 2 30's will provide. I've run my 50amp 5er on a 30/15 pigtail for an entire weekend and never noticed any difference. I have 15k & 13.5k a/c's, 3 tv's, 2 microwaves, and 3 daughters. I also have a hard wired EMS to monitor line voltage.
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Old 09-15-2013, 08:03 PM   #6
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Originally Posted by JJvike View Post
Hello all,

Apologies if this has been covered but I could not find it. At our tailgating we share a pair of boxes with another rig. One box is a 50 and it seems we both want it. We've split so far this season. The other box has 2 30 plugs with individual breakers and 1 20 with a breaker. I ended up using one of the 30s with my 30 to 50 cord. Some one came up and offered the use of his "2-30s to a 50" cord and says it will give me everything I would get from the 50. Since I'm new to this, I said thanks but stayed with the 30.

Did a search after I got home and found this
Amazon.com: Conntek RV 50-Amp Power Optimizer (2) RV 30-Amp Plug to 50-Amp 125/250-Volt 14-50R Female Connector: Sports & Outdoors

I own a 2013 Berkshire and, as you can tell, I'm not electric savvy. Will using this give me all the power that a 50 will and will I be safe from any potential damage to my system?

Thanks in advance,
JJ
Will work just fine. As others have mentioned they actually make a 15/30 to 50. Your 30/30 to 50 will be fine. May just have to use some power management because you wont have the full 50 amp service which is actually 100 amps of power. You will have 60 amps.
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Old 09-15-2013, 08:05 PM   #7
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...
I've run my 50amp 5er on a 30/15 pigtail for an entire weekend and never noticed any difference.
So somehow, based on your experience with running up to 45 amps thru your 50 amp neutral, you conclude that it's ok to run 60-amps thru a 50-amp neutral?
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Old 09-16-2013, 06:51 AM   #8
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So somehow, based on your experience with running up to 45 amps thru your 50 amp neutral, you conclude that it's ok to run 60-amps thru a 50-amp neutral?
Barry, there will never be more than 30 amps on that neutral since the hot will alternate. The wires should be fine; no?
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Old 09-16-2013, 08:51 AM   #9
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Barry, there will never be more than 30 amps on that neutral since the hot will alternate. The wires should be fine; no?
You can't just assume that the "hot will alternate". It totally depends on how the electrician wired up those two 30-amp outlets in the pedestal. That's the whole point of measuring for 240v to see if, in fact, they are alternating.
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Old 09-16-2013, 05:16 PM   #10
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Originally Posted by BarryD0706 View Post
You can't just assume that the "hot will alternate". It totally depends on how the electrician wired up those two 30-amp outlets in the pedestal. That's the whole point of measuring for 240v to see if, in fact, they are alternating.

OK...
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Old 09-16-2013, 06:48 PM   #11
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Originally Posted by BarryD0706 View Post
You can't just assume that the "hot will alternate". It totally depends on how the electrician wired up those two 30-amp outlets in the pedestal. That's the whole point of measuring for 240v to see if, in fact, they are alternating.
Barry, I thought most 50 amp campers are wired with most accessories on one of the hot legs and only the second A/C on the other leg. This is where the 15/30 cheater came into play so those could get the second A/C running.

IF this is still the case I don't think there would be an issue overloading the neutral.
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Old 09-16-2013, 07:20 PM   #12
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You won't over load the neutral with the 15/30 adapter. 15+30=45 amps. If the outlets are from the same leg of source, the neutral will only have a maximum of 45 amps. If the outlets are from opposite legs of source, the neutral will have 15 amps for 1/120 of a second and then 30 amps for 1/120 second and then 15 amps for 1/120 second, etc, etc.
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Old 09-16-2013, 07:28 PM   #13
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You won't over load the neutral with the 15/30 adapter. 15+30=45 amps. If the outlets are from the same leg of source, the neutral will only have a maximum of 45 amps. If the outlets are from opposite legs of source, the neutral will have 15 amps for 1/120 of a second and then 30 amps for 1/120 second and then 15 amps for 1/120 second, etc, etc.
He isnt using a 15/30 its a 30/30 for a total of 60 potential amps. If the two 30 amp plugs are not split phase then you could overload the neutral
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Old 09-16-2013, 07:54 PM   #14
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Barry, I thought most 50 amp campers are wired with most accessories on one of the hot legs and only the second A/C on the other leg. This is where the 15/30 cheater came into play so those could get the second A/C running.

IF this is still the case I don't think there would be an issue overloading the neutral.
I'm glad to see (in later posts) that you see the potential problem. I can't speak to "most campers", but in mine, both ACs are on the same leg, with much of the other "stuff" on the second leg. I agree with you that having <20 amps potential load on one of the legs also makes the problem go away. (That comes under the category of manually managing that you stay under 50 amps to me.)

How likely is this to happen? Lets assume that we have two electricians wiring up the campground. The Master electrician knows that the loads need to be shared between the split phases so he wires up the red wire to the hot of one of the 30-amp outlets and the black wire to the hot of the second 30-amp outlet. He wired up a few of the pedestals and then leaves the rest for the Apprentice electrician.

The Apprentice knows there's a color scheme that makes everything easy. On 50-amp outlets you connect up the Green, White, Red, & Black. On 30-amp outlets, you wire up the Green, White, and Black. Two 30-amp outlets in a box? No problem! They both get wired to the black (white & green).

Do you know which electrician wired up your pedestal? Only one way to know for sure.
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Old 09-17-2013, 11:04 AM   #15
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Has the OP tried to get by with just the 30amp plug? I can run both my a/c's on a single 30, along with what we normally use in the camper. Of course, water heater is on propane. Without looking back, was there a 15/20amp circuit in the pedestal at all? If so, (and not a GFI), could use 15/30 pigtail and not worry about any of it.
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Old 09-17-2013, 07:41 PM   #16
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Thanks for the replies. Most of it is over my head but I think I follow some of it. To answer ttrost65, I did use the 30 for the weekend. I ran both A/C's only once during the heat of the day. Everything else was off except the satellite/2 TV's. As we approached dinner my wife used the microwave and the circuit tripped. Shut off the rear A/C, reset and proceeded without any further skips. We took the grandbaby and wanted to wash some of his clothes, but I assumed the dryer would do the same as the microwave. The box I used had 2 30 plugs w/separate breakers and a normal plug with a 20 amp breaker. I just don't enjoy having to pay that much attention to what I use when I'm trying to tailgate. If the 30/30 to a 50 won't work then I guess I will have to manage without.

Thanks again for the info.

JJ
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Old 09-18-2013, 04:07 PM   #17
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If the 15 is not a GFI, you could use the 30/15 and be fine.
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