Community Forums

windman · 03-04-2018, 07:46 AM

Still searching for some information if I can use a 50A EMS (progressive industries) on a 30A trailer and get the same protection that with a 30A EMS?

I found that comment on e-trailer :

Expert Reply:
You can use a 50 amp surge protector on your 30 amp service but I would offer a bit of caution. If any of your appliances or items are rated at 30 amps and something happened that caused them to draw more power, the 50 amp surge protector would not trigger and you could suffer damage to those items.

What I don't understand on that "EXPERT REPLY" is whatever I have a RV with 30A or 50A entry, my appliance that is rated for 30 amps...says a fridge...will still be rated for 30A even if I have a RV that has a 50A entry for such with 2 air conditioning.

What am I missing?

docj · 03-04-2018, 08:00 AM

My suggestion is to simply ignore the so-called "expert opinion" and do what you were planning on doing. A surge suppressor is not like a circuit breaker; it doesn't "trip" at a particular current level. Furthermore, the most important part function of the device is its power management function which protect you from high/low voltage, miswired pedestals, etc. Your trailer and the devices in it are always protected by the main 30A breaker and the subpanel breakers. There is no way they can draw more than that without tripping those. The 50A EMS will work fine for your application. Like so many posts on the internet, this particular expert post is garbage.

I'm not quite sure why you're planning on using the 50A EMS rather than a 30A. I assume that you already owned one or got a great deal on one. Normally there would be no reason to buy this device to use with a 30A trailer.

SailorSam · 03-04-2018, 08:14 AM

Caveat, I'm not an electrician...

With that said, it is my understanding that the EMS does NOT protect you from excessive amperage usage. (am I saying that right?) That is the job of the circuit breakers.
I suspect the difference in the surge protection ratings is the result of having 2 feeds protected on the 50 amp version. That has 2 hot legs versus the 1 hot leg in a 30 amp. So the "modes" are the routes the surge can take - h->n, n->g, h->g, then with 50 amp add another h->n and h->g...
I have read plenty of posts of folks recommending getting the 50 amp version so that you can move it if you upgrade to a larger trailer. Never saw anyone argue against that for electrical reasons.
So, I think you are safe with either a 30 or 50 amp unit in a 30 amp RV. You are simply using 50% of the capability of the EMS. You have to decide if you are really likely to upgrade and if spending the extra money now, with extra effort later is really worth it.

windman · 03-04-2018, 08:47 AM

Quote:

Originally Posted by docj

I'm not quite sure why you're planning on using the 50A EMS rather than a 30A. I assume that you already owned one or got a great deal on one. Normally there would be no reason to buy this device to use with a 30A trailer.

I'm not sure yet if I'm going to get a 30 or 50A TT, and I have the opportunity to buy it now since I have a feet in USA where it is cheaper for me. And if I ever upgrade TT to a 50A, I will have it .

Brentw · 03-04-2018, 09:27 AM

Interesting question, I get your reasons. Agreed all of the protection will be there and over amperage will be protected by the existing breakers. But now that I am thinking of it, what will the ems do when it sees only 1 leg hot. Adapting a 50 amp system to a 30 ( thru a dog one adapter) ties the to hot legs together, so ems is happy. But when you wire in a 50 on a 30 you will only be using L1 of a 220 v system.
Hmm.. will it sense only 1 leg and shut down?

Bob_C · 03-04-2018, 09:32 AM

You wire in the 50 amp one the same as a 30 amp one....there are diagrams on how you do this

Brentw · 03-04-2018, 09:59 AM

Sorry Bob, not seeing this. Just wired in a 50 in my unit. Went thru installation instructions again, don't see it. A 50 will have L1, L2, N, Ground, a 30 has L1 , N, Ground. There is no mention of jumpering of L1/L2. And not sure I would do this in this unit.
Without power on 1 of these legs, I believe the unit would have an error code of low voltage on the leg without power.
Or what am I missing?

Bob_C · 03-04-2018, 10:14 AM

You need to check out Forest River Forum......different then the one here, and there is info there

docj · 03-04-2018, 10:20 AM

Just use a 30A to 50A adapter ahead of the EMS which will feed power to both legs of the EMS. Then use a 50A to 30A adapter to connect to the trailer's power cord. A bit of a kludge but it should work.

windman · 03-04-2018, 11:18 AM

Quote:

Originally Posted by docj

Just use a 30A to 50A adapter ahead of the EMS which will feed power to both legs of the EMS. Then use a 50A to 30A adapter to connect to the trailer's power cord. A bit of a kludge but it should work.

I will get the hard wire one so I need only one way 30 to 50

windman · 03-05-2018, 06:41 AM

Here is the question I ask:

Can I use a EMS HW50C on a 30A trailer? Same protection?

The answer:

Hi Francois

Good morning

Yes you may

Thank you

Anthony

windman · 03-05-2018, 07:20 AM

I called PI about connection of a 30A thru a 50A EMS. Since the 50A is L1, L2 and L3, and the 30A is L1 and L2 only they will be giving me special instruction not listed in the web site or instruction how to connect. They where talking about connecting L1 and L3 together or something like that. I will post back when I get the proper instructions.

windman · 03-05-2018, 11:25 AM

Ok just talk with PI. and for connecting a 50A EMS on a 30A TT you just need to make a jumper between L1 and L3 and connect your 30A Black to L1 and White L2 as for normal 30A EMS. At the exit just use the magnet over the Black wire