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 > 50amp EMS w/surge

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CA Traveler

The Western States

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Posted: 04/17/21 07:57pm Link  |  Quote  |  Print  |  Notify Moderator

Let’s try some clarification: Yes if you short the 2 hots on the 50A pedestal the CB will trip. But that is not what the 30/50A RV adapter does. The adapters 30A male ground is connected to the 50A female ground plug. Neutral is connected to neutral. The 30A hot wire is connected to both of the 50A hot wires. This provides 120V to both hot legs so that the RVers has the convenience of 120V at all locations in the RV. An adapter that connects only one leg of the 50A cord would be a non RV product.

A EMS that detected the lack of 240V and blocked power or only allowed power to one leg would also be a non RV product since the user wants 120V everywhere in the RV.

Fortunately EMS units have no 240V related restrictions and they work as expected with a 30/50 adapter or a 20/50 adapter or with 50A and they detect a variety of faults. My PI unit has 11 error codes and between it and the pedestal CB the RV is provided significant protection.

Virtually all 50A RVs have the above 2 adapters. And many have the full power function EMS units.

The 50A pedestal power comes from a transformer secondary center tapped winding. The Center tap is the neutral. Because the power comes from a single winding it can only be single phase. Yes you can assume that the neutral is the reference are refer to it as 2 phases as is sometimes done. Typical home power is the same except that it’s higher amps like 200A. But both the 50A pedestal and home power is single phase. Wikipedia has explanations on this.

I can only recall one post from a RVer that was in a mobile home park that had 120/208V power. That is part of 3 phase power and the 2 legs are 120 degrees apart. But since it’s a rare RV with 240V appliances there won’t be a issue.

The bottom line is that the adapters and EMS units work well and provide reasonable options for connecting a 50A RV to 20A or 30A.


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ScottG

Bothell Wa.

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Posted: 04/17/21 09:03pm Link  |  Quote  |  Print  |  Notify Moderator

And Bobs your uncle [emoticon] (insert mic drop here).

* This post was edited 04/17/21 09:37pm by ScottG *

pianotuna

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Posted: 04/18/21 09:10am Link  |  Quote  |  Print  |  Notify Moderator

Use a dog bone 30 to 50 adapter before the EMS. All will be well.


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Mr. C

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Posted: 04/19/21 10:01am Link  |  Quote  |  Print  |  Notify Moderator

Thanks to all for the info...

Now to get rid of my EMS-PT30-C...


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CA Traveler

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Posted: 04/19/21 10:43am Link  |  Quote  |  Print  |  Notify Moderator

I chose the hard wired version for 2 reasons:
1. Always installed
2. Inside remote

One time installation of course.

Mine cost $0.00

Well OK Paid for it in 2005 and hence no cost for current RV.

Usage tip: Always have all high amp loads off when connecting or disconnecting power which reduces AC arcing on the relay contacts.

dodge guy

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Posted: 04/19/21 11:22am Link  |  Quote  |  Print  |  Notify Moderator

If you can get the portable, but wire in a make and female plug in the compartment. This will keep it safe. And for whatever reason will be easy to bypass.


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Route 66 Traveler

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Posted: 04/20/21 07:55am Link  |  Quote  |  Print  |  Notify Moderator

I have a Progressive PT50X 50amp and it works just fine from a 30 amp source or my Predator 3500 generator. I have also had to use it at Campgrounds that only had 30 amp hookups by using the provided 50 to 30 amp adapter from Progressive.

I prefer to have the portable unit because I can check the power before parking at a campsite, plus if something does go wrong with the unit it won't stink up the RV with smoke.

This is my second unit from Progressive. My first one had the cord come loose from the plug. It still worked OK but it was hanging from the wires and not the cord. Progressive replaced it within 7 days from the time I submitted a warranty claim...great customer service.

ScottG

Bothell Wa.

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Posted: 04/20/21 09:07am Link  |  Quote  |  Print  |  Notify Moderator

dodge guy wrote:

If you can get the portable, but wire in a make and female plug in the compartment. This will keep it safe. And for whatever reason will be easy to bypass.


Hardwired version is easy to bypass. Simply flip a switch.

dodge guy

Bartlett IL

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Posted: 04/20/21 03:01pm Link  |  Quote  |  Print  |  Notify Moderator

ScottG wrote:

dodge guy wrote:

If you can get the portable, but wire in a make and female plug in the compartment. This will keep it safe. And for whatever reason will be easy to bypass.


Hardwired version is easy to bypass. Simply flip a switch.


I don’t believe it is on the Hughes Watchdog.

ScottG

Bothell Wa.

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Posted: 04/20/21 03:33pm Link  |  Quote  |  Print  |  Notify Moderator

dodge guy wrote:

ScottG wrote:

dodge guy wrote:

If you can get the portable, but wire in a make and female plug in the compartment. This will keep it safe. And for whatever reason will be easy to bypass.


Hardwired version is easy to bypass. Simply flip a switch.


I don’t believe it is on the Hughes Watchdog.


I dont know either. I was assuming this was in reference to the PI Hw50C mentioned earlier. I should have mentioned that model in my post.

* This post was edited 04/20/21 03:50pm by ScottG *

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