Forum Discussion

Sandy___Shirley's avatar
Dec 07, 2020

Which EMS Surge Protector

Just got our RV back from the repair shop! We had a 5th wheel for 10 years then changed to a motorhome 5 years ago. We had our first electrical failure in October. The Surge, or whatever, fried our inverter and the circuit board that ran the heat in our bedroom. The cost was over $1,000, but only cost us the $100 deductible on our insurance.

We made our first post on this on 10/6/20 and have been doing a lot of research since then. One possibility was the hardwired Progressive EMS-HW50C. Then we started thinking about the post mounted EMS-PT50X so that we could check out the campground wiring before pulling out the extension cords.

After further research we have added the Southwire 34951 to the list.

As we understand it, the Progressive units have been around for about 10 years, so there are a lot of posts about them. The Southwire 34950 has been around only 2 or 3 years, so far less posts, and the 34951 is the new upgrade that includes a remote Bluetooth monitor.

There is a TechnoRV article that does a good job of comparing the two units:
Do you need an rv surge protector

If we understand our research so far, both post units are about the same, Southwire costs a little more, Progressive take about 2 minutes to analyze the power while Southwire can do it in 10 seconds.

A big question to the group is: TechnoRV gives their gold star to the Southwire unit, does anyone know if the two companies are in any way related?

And of course; what are your opinions of the two units? Progressive EMS-PT50X vs Southwire 34950/34951
  • In addition to the above post, an autoformer will have your appliances running with voltage that is closer to the optimal so the appliance will be more efficient.
  • Sandy & Shirley wrote:
    Progressive take about 2 minutes to analyze the power while Southwire can do it in 10 seconds.
    Not exactly. The power is evaluated immediately and continuous. The Progressive does have a two minute delay to verify power is stable before the switch closes. Also the delay will be restarted if there is temporary problem. This prevent your air conditioner from an immediate restart if the issue is only for a split second.

    From the manual:

    Time Delay for A/C Compressor: If AC power is interrupted or the EMS detects a fault condition, the built in time delay is activated. There are two settings on the EMS: one is 136 seconds (02:16), and the other is 15 seconds. Consult your air conditioner manual to see if it has a time delay built in. If so, use the 15 second delay, if not, use the 136-seconds delay. The factory setting is 15 seconds.

    https://file.powerprodllc.com/-/media/inriver/ZX480.pdf

    Certainly if the voltage is moving just above / below the cut-off point you don't want all your electronics to be cycled on-off every few seconds until you unplug them.
  • time2roll wrote:
    The power is evaluated immediately and continuous. The Progressive does have a two minute delay to verify power is stable before the switch closes. Also the delay will be restarted if there is temporary problem. This prevent your air conditioner from an immediate restart if the issue is only for a split second.


    This is one thing my system does not do--but I can get around it by using load support on the inverter/charger. It is one reason I want such a large bank of truly deep cycle batteries.
  • Lynnmor wrote:
    In addition to the above post, an autoformer will have your appliances running with voltage that is closer to the optimal so the appliance will be more efficient.


    I love getting full wattage from my electric heaters in the winter.
  • pianotuna wrote:
    The absolute lowest voltage I've seen is 100.
    I have seen the low 90s one time. Too low even for my 16% booster to correct. No cool air until the sun went down. I felt bad for the others that had no idea. Brand new place too on the east side of Glacier.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,191 PostsLatest Activity: Jan 19, 2025