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Old 04-10-2012, 06:39 AM   #15
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It's not just surges that concern me.... You could plug into 240 unaware. This thing does much more that just surge protection: http://www.progressiveindustries.net/ems_hw30c.htm

And another tread on this topic: http://www.airforums.com/forums/f199...tor-83648.html
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Old 04-10-2012, 11:33 AM   #16
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Originally Posted by NevadaGeo View Post
Just a curious question, do these (or any) surge protectors protect from the neutral becoming "hot"?
Some of the autotransformer-type ones do, as part of their proofing of the supply voltage before turning everything on.

You can also check manually with one of those little three-light ground testers before you plug in. I have one in the shore power compartment of my trailer but hardly ever use it.

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I've had that situation in this house more than once: Tree falls on the power service on the house side of the meter pole. One of the hot wires breaks and then contacts the neutral, which energizes the neutral side of all the appliances in the house, bypassing the ground wire at the breaker box on the house. Most appliances don't like the neutral to be hot. Electric company replaces the appliances. Next storm, tree falls on the power service on the house side of the meter pole.
In the North American wiring tradition, neutral and ground are bonded together at the service entrance in residential wiring. Grounding practices elsewhere are different. One disadvantage of the North American way of doing things is that a short between hot and neutral in the distribution system also causes high ground currents to flow and that's what causes the damage.

RVs aren't wired that way -- the ground is isolated from the neutral.

A properly wired RV set up for 30a service won't be affected by reversal of neutral and hot, except that the safety advantages that come from switching the hot instead of the neutral would be lost.

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It's not just surges that concern me.... You could plug into 240 unaware. This thing does much more that just surge protection: EMS-HW30C
I think the problems with open neutrals in the campground wiring are really the only plausible reason to have any sort of power conditioning. Open neutrals can show up under heavy load as a result of poor wiring practices and lead to severe under and over voltage at the pedestal. Depending on the situation you could conceivably damage anything that isn't prepared to deal with 240 volts and that is actually drawing power while you're plugged in.

That's one of the reasons I like the TrueCharge converter. It would ride through something like that because of the wide input voltage range.

That leaves the air conditioners, fridge, water heater, and microwave.

The water heater would pop a breaker on 240v before damaging anything.

The fridge will blow the internal fuse if present or require a new element if not. Either way you can still run it on gas until repairs can be made.

Air conditioners would probably be OK because it's so unlikely to get way over 120v as a result of an open neutral while the air conditioners are running because of the symmetry of the load though it is possible that there will be fan motor or compressor damage if they do.

No idea on the microwave. They are inverter designs internally and not usually very picky about voltage.

So, sure, the possibility of damage is there, and open neutrals though rare do sometimes occur. Technically it's the campground's responsibility to pay for repairs (or their insurer's) but I realize that it's nearly impossible to collect on a claim like that.

Most RVers will travel for a lifetime without running into problems like this.

I'd rather take my chances than pay the upfront cost weight and hassle of one of the expensive power conditioners. Remember that the cheap ones don't help with this.
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Old 04-10-2012, 11:44 AM   #17
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We used to have one of the ~$99 models for our Bambi until one hot day in the summer while running the AC, the female end of the protector and the male end of our shore line decided to overheat and begin to melt.
Combination of poor quality female connector on the surge thingy and a little corrosion on the shore power line, probably. I try hard to avoid extra connections because of this sort of thing. Without the surge thingy you would have been fine. ::shrug::

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...[it] seems worth it to us.

Shortly after we got it we were in a park where we had camped several times. While watching movie one night all of a sudden the power went out. I went to investigate and sure enough, the surge protector had interrupted the current and disconnected our rig from the power source. Curious as to why, I plugged the shore power line into the post outlet and discovered the voltage had dropped significatnly below acceptable ranges. So the surge protector had done one if it's jobs... I reinstalled it and when the current was within acceptable ranges again, it reconnected and we were good to go. We would never have known that this was happening without the protector unless we sat there staring at the voltage meter plugged into an outlet all evening. We have no idea why the voltage dropped, but it happend for 4 nights in a row at this park.
This story is very common and sells lots of these things.

The problem is, though, that chances are that the voltage wasn't off by enough to really matter. The "acceptable range" outside which the surge protectors will pitch a hissy fit is deliberately chosen to be narrow by the manufacturers of the devices to convince their customers that the devices are worthwhile.
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Old 04-10-2012, 02:06 PM   #18
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That leaves the air conditioners, fridge, water heater, and microwave.
... and the flat screen, and any other custom electrical device not powered by the converter.

When it comes right down to it, an Electrical Management System (which includes surge protection) is like insurance: you don't have the need until the unexpected happens.

We all buy insurance, some paying more for better coverage - all based on our assets and comfort zone there of ....

Only having surge protection is like having only theft coverage on your insurance policy: it doesn't cover collision or fire.
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Old 04-10-2012, 07:55 PM   #19
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Combination of poor quality female connector on the surge thingy and a little corrosion on the shore power line, probably. I try hard to avoid extra connections because of this sort of thing. Without the surge thingy you would have been fine. ::shrug::



This story is very common and sells lots of these things.

The problem is, though, that chances are that the voltage wasn't off by enough to really matter. The "acceptable range" outside which the surge protectors will pitch a hissy fit is deliberately chosen to be narrow by the manufacturers of the devices to convince their customers that the devices are worthwhile.
Maybe. Maybe not.
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Old 04-10-2012, 10:07 PM   #20
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Wow Brian, with 1000 nights so far, and no events which might justify a surge protector, perhaps your the poster boy for the argument that they are unnecessary

But, as Airtandem says, it only takes once. I have a Surge Guard 32730....
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