Community Forums

chris cross · 02-07-2007, 06:45 AM

We're at a ranch in Tubac, AZ. with a 30amp. (I think 20) plugin. We have a 50 amp. SurgeGuard hardwired. The Prosine 2.0 inverter screen says "Warning: Rev Polarity". The ac in light blinks and the inverter does not function. This is fine and well. I guess the systems are protecting everything. However, if I disable the inverter the ac comes through the SurgeGuard and powers the coach to it's 20 amp capability. It will run the charger and the ancillary equipment. Now this surprised me. I thought all ac had to run through the inverter. Am I endangering anything? Doing this eliminates the need to run the genset to recharge.
Thanks

chris cross · 02-07-2007, 06:45 AM

We're at a ranch in Tubac, AZ. with a 30amp. (I think 20) plugin. We have a 50 amp. SurgeGuard hardwired. The Prosine 2.0 inverter screen says "Warning: Rev Polarity". The ac in light blinks and the inverter does not function. This is fine and well. I guess the systems are protecting everything. However, if I disable the inverter the ac comes through the SurgeGuard and powers the coach to it's 20 amp capability. It will run the charger and the ancillary equipment. Now this surprised me. I thought all ac had to run through the inverter. Am I endangering anything? Doing this eliminates the need to run the genset to recharge.
Thanks

EngineerMike · 02-07-2007, 07:31 AM

Proper polarity is a basic safety issue, i.e. the Neutral, usually white, wire which is eventually tied to earth ground is the energized part of an appliance that might be touched while in operation. E.g. for a light bulb, the metal threads of the screw base and the corresponding portion of the socket are the N side of the circuit, and the Hot side is the button on the end of the bulb and the inside center of the socket. Theory is that it is a) hard for people to contact the obscured H side parts and b) that the grounded N side is safer under all conditions as it's usually the most electrically expedient path to ground (thru the low resistance copper wiring and not you). Since the current is "alternating," the actual operation of most appliances is unaffected; ie. the gizmo can't tell the difference and works just fine.

With that said, I have a hot plate with an improper plug that can go into the outlet either way; if it goes in w/reverse polarity, I fell a funny tingle (shock) when I contact the metal case or a metal pan on the burner. If I stood in a puddle and grabbed it while energized w/reverse polarity, I might get a not-so-funny tingle as the current now prefferred me as a path to earth ground (since the appliance is high resistance and me less so), with the H side grounded thru me before the current runs thru the appliance. Now that's w/dumb appliances. Computerized stuff could easily contain circuits that "use" the polarity in some clever way, and may not operate properly or may be damaged.

If you are electrically handy, and you can expound more on "30amp I think 20" there may be simple solutions we can suggest. Before that, I'd report it to the camp office and see if they have somebody who will properly polarize the space's outlet connection.

chris cross · 02-07-2007, 08:15 AM

Thanks EM: I guess that "electrically handy" is relative. The camp lady says the plug is 30 amp. but the breaker that keeps tripping looks to me like a 20 amp. Also, I don't feel that I'm putting enough load on the system to trip a 30 amp breaker. By the way, this "camp" is like a 60's commune with "Massage Therapy" as an advertised service. Maybe that would reverse my polarity.

Ted III · 02-08-2007, 03:01 AM

I have mentioned things that we had electrically on our boats as they really are very similar to RV's. The only big difference is the boat manu. have a real thing about huge electrical panels, circuit breakers & switches. It also seems that it needs to be in clear sight of all that enter the boat behind smoked glass doors with all kinds of red & green lights. The more the merrier. It's a man thing as my wife hated all of them and wanted to know if they could be moved out of sight. Although they may me be a bit on the overkill side there are some interesting and beneficial items. One of the simple items was a relay that would automatically kick the main breakers off if you plugged into a reverse polarity plug. Great idea, not very expensive, why are they not in Alpine coaches. It would not be a hard item to add to our existing coaches but why do they not come standard, in the Alpine & other coaches?

EngineerMike · 02-08-2007, 06:30 AM

Ted- Just a guess: boat wiring standards might consider the threat of severe shock from contacting the ungrounded energized parts of 110 appliances on a boat to be extreme, and therefore it may be addressed in that code. I'm pretty sure it isn't in terrestrial vehicles or else we'd have the gizmo.

SteveS · 02-08-2007, 01:00 PM

There is hardly any place easier to get electrocuted than in a boat. You are surrounded by a giant ground plane and the electrical path to ground inside a boat is solid. Therefore if there is a bad neutral/return and you contact the device, guess what...you provide the path to ground...shocking I'd say!

Additionally, with constant moisture around, electrical systems are more likely to fail. Therefore, ample warning and safety devices are not excessive, they are necessary.

Ted III · 02-09-2007, 03:15 AM

E Mike & Steve S, I agree thouroghly with your comments about a boat being considerably more dangerous if a reverse polarity were present. I am in total agreement. On the other hand if motorhomes, trailers, etc. were setup the same way this post would not exist.