I suspect that 30a is insufficient

[uncle_bob]

Hi

Ok, what *should* be going on with each of these gizmos:

First up is a pure surge protector. It clamps your 120V input voltage at something in the 600 to 800V range. It *starts* the clamping process before that point, but does not fully limit until it gets up into that range. If you are worried about lighting these are fine devices. As a side note, they now are required items on newly built homes.

Next up is what Progressive calls an EMS and other folks have their own name for. It looks at the various voltages and makes a decision Are the neutral and ground hooked together? Is leg 1 at a reasonable voltage? Is leg 2 (if this is a 240V unit) at a reasonable voltage? Is the frequency reasonable? Once all of this is correct and has been for a while, the relays go thunk and power is passed through the device. If something goes wrong with any of those numbers, it disconnects.

Typically the gear in the second category also includes surge protection.

So what can go wrong?

Surge protectors only last for some (generally unspecified) number of "hits". Past that they simply don't do any good. They are very much *not* forever devices. Working out if they still are doing well is not at all simple. This is true of the RV version, it's also true of the ones you buy to plug your computer into at home. The only exception are the higher end versions designed to handle a full home.

The "EMS" stuff works with relays. They are slow compared to a surge protector. Something goes wrong and you may have 10's of milliseconds of delay before things disconnect. Not perfect but usually quite adequate.

None of these "EMS" gizmos do much good for faults that occur after the device. Pug it into the post and your power cord, connectors, and trailer wires are not protected. Pretty nasty problems *can* occur in this area.

It is claimed that with a large hit, a surge protector can explode. In many decades doing this sort of thing and talking to a lot of folks, I have never run into anybody who has ever had this happen to them or seen it happen. If it happens, one would very much like to know the make / model / age of the device involved.

So, are these a perfect solution to all the problems you possibly run into? Certainly not. They cover a range of issues and do provide protection against a lot of pretty normal things folks do run into on a regular basis. Ours disconnects us several times a season.

Fun !!

Bob

[crispyboy]

Interesting topic.
Our trailer is a bit older - 1994 with a 30amp service. It came from the factory with a switch in the cabinet where you select either the microwave or the AC unit. Keeps us from blowing breakers. On really hot days we try to cook outdoors so we don't have to shut the AC unit down. I'm sure it doesn't do the compressor any good with the on/off cycle. Cross my fingers every year as it is the original AC unit.

In the summer I have frequently found low voltage conditions when everyone is running their AC. I can manage loads enough with turning off the converter during the day, switching the refrigerator to propane and the water heater is propane only. I use a surge protector and it has a nice readout of the voltage and amps.

I would love to have a second AC and would not have any issue with changing to a 50A service but it is more an issue with trying to fish an electrical wire and drain line for the second unit.