Autoformer versus Surge Protector

I like the EMS conversion (how I'll likely do it).

I use a HUGHES autoformer. as does my current neighbor. Need 'em here still got lower than I like voltage (but high enough) per ye old meters. I meter both lets AND the Inverter line as well. (well one meter I got 13 years ago one (kill-a-watt) later for other use (it still does that but works as a line monitor most of the time) and the 3rd meter was... $0.00 shipping included!!! (Ok I won a prize) nice expanded range analog job from MFJ enterprises.

All are checked against my calibrated bench meters.

I mounted the Hughes for 4 reasons...
1: as noted it is HEAVY and I mean HEAVY and this leads to #2
2: For an overnight the tendency is to say "Forget it" and guess what I had one night where I kind of wish I had not. No A/C problem but voltage was low. (A/C off that night. furnace on). Microwave was not happy though. Wound up switching to inverter power for That).
3: I have been to parks that say "NO AUTOFORMERS".. So They will never see me plug in an Autoformer.. I simply don't do it.. And no I do not show 'em where it hides either.

4: Legs.. I used to have a real nice Generac 1000 Generator. Just enough to power the Progressive Dynamics Converter on this RV. but it grew legs and I've not seen it since. My Autoformer cost more than that generator. but where it is hiding legs are not an option.

"Cord caps"

I have no such extra connections. Pulled the romex out of the panel and connected direct in the PI EMS. Added a section of romex to connect PI EMS to the main panel.

I do use the plugs for my booster for part time use only as needed. All that is located in the cord compartment.

Cummins12V98 wrote:
I have mine connected with 50A cord caps. A couple un plugs and a plug in is completely removed. So I could say mine is not hard wired into RV.

Took me a moment to figure out what you meant by "cord caps" but I suspect this is how many of us actually install a hard wire EMS into our rigs. Much more versatile. :B

I have mine connected with 50A cord caps. A couple un plugs and a plug in is completely removed. So I could say mine is not hard wired into RV.

2edgesword wrote:
The Hughes autoformer units I see advertised boost voltage and provide surge protection.

And your point would be? :h One wouldn't buy either an EMS or an autoformer for surge protection but rather because an EMS won't pass faulty power on to the rig OR an autoformer because it will boost low incoming voltage in stages. Surge protection with either is merely an additional feature, not the reason to buy one in the first place.

The Hughes autoformer units I see advertised boost voltage and provide surge protection.

haven't we had this article 551-20 discussion before
and doesn't it refer to OEM builder mfg
NOT to owner add on

Of interest and something to be aware of is that the Hughes internal mounting kit isn't code legal if installed inside an RV. Article 551-20 specifically prohibits the use of autotransformers (autoformers) inside RVs.

Also of note is that while the Hughes' autoformer contains UL components, the unit as a whole isn't UL approved which is not the same thing. Only UL approved/listed components and materials are permitted by the NEC which is another reason why the Hughes units are not code legal. Good 'ol CW lists the Hughes unit as being UL listed, which it's not...

While you might be just fine if it's mounted inside in a safe manner, has adequate ventilation and has the required clearances and access, if you ever had a fire or someone got a shock, you might be in hot water with an insurance company or AHJ. Having said that, many (me included) have done all sorts of various electrical modifications and nobody needs to take out a permit or required to get an inspection done by an AHJ.

I made some mods to our Hughes autoformer so it can sit underneath our TT versus having to be at a pedestal. Stays dry and is more out of sight.

I have the EMS-HW50C and the Hughes Autoformer with the Internal Mounting Kit inside the trailer. I also use a SSP-50XL at the pedestal. I plug the SSP-50XL in first thing (now) to make sure power is good before setting up.
I did have to move one time (after I got set up:S)