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Old 07-10-2013, 09:28 PM   #85
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The 50A service is 50A x 220V or 11,000W a 30A service is 30A x 120V or 3600W. The 50A service is 3 times more power than the 30A connection. You can run both AC units the microwave and an electric hot water heater. P=IV and V=IR ohm's law.

Remember your physics courses.

Perry
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Old 07-11-2013, 07:10 AM   #86
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ive heard 100 and now 108....if <108, this is a problem then? What happens in such a case? Or what can happen (i presume higher loads more likely to flare up the issue?).

The TRC safeguard will protect from lower voltages as well correct? At what point does the TRC unit trip? 108? 100?
Not sure of the exact spec on the TRC, but they generally run +/- 10 %, which gives you a range of 108-132VAC. At lower voltages (brown out), the amp draw of a given appliance rises and can easily trip a circuit breaker or damage the appliance. The TRC would shut the incoming power in a low voltage situation like that, saving a potential melt down in the trailer.
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Old 07-11-2013, 08:24 AM   #87
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@Perry...I took two semesters of physics in pharmacy school...I have repressed it...trying to think about it induces PTSD!

@lewster - got it....good to know...follow up question then....lets say you get to a camping spot - the readin is 107 or 108 (or some number lower lets say)....at what point do you just forgoe hooking up to that hookup alltogether?
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Old 07-11-2013, 08:31 AM   #88
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Personally, I never hooked up at a pedestal lower than 115VAC. I would ask to look at a few other sites and if they were all that low.....change campgrounds!
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Old 07-11-2013, 08:35 AM   #89
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sorry, dont mean to be really detailed, but it seems from my reading and discussion so far that common RV folks benefit from checking for proper voltage..if too high, then do not plug in...too low, then do not plug in...if polarity is screwed up...same. Surge protector a good idea to protect from such things as they

But I guess it may be instructive to perhaps list out or lay out a number of scenarios where we should not plug in...and be specific.

for example at x low voltage, or at y high voltage, or if the cord looks melted from possible previouis over-heating.

It is certainly good to know that that even if I miss something, the surge protector will trip with most of these issues.

Thanks you all...this has been very helpful!
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Old 07-11-2013, 08:37 AM   #90
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woops, lewster, did not see your last post before posting last...noted....thanks.
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Old 07-11-2013, 09:53 AM   #91
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One more book you might consider:
RV Electrical Systems by Bill and Jan Moeller.
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Old 07-11-2013, 04:46 PM   #92
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If your are getting less than 110V with no load then you have a problem. Anything less than 100V under load is going to start burning things up. The power disipated in a device is the current squared times the resistance. So things really start to heat up as the current rises and the voltage drops. This is the same reason you need big wires to run small loads at 12V. To run 1000W at 12V requires 83A. To run 1000W at 120V it takes 8A. This is also why running your fridge on 12V will suck a battery down in no time at all. 300W/12V = 25A.

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Old 07-15-2013, 09:35 PM   #93
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The plug on the right and the yellow polarity tester are all you need to check any 30 amp safe for your trailer. Just plug it in look for the correct lights, unplug it and plug in you shore power cable. I have done something similar at marinas for 30 years.
It is not going to tell you whether you draw too many amps for an inadequate shorepower service, but with a normal campground 30 amp and a stock trailer that should not be an issue.
Larry
In another thread on surge protectors, I followed a link to this: http://www.progressiveindustries.net/ems_pt30c.htm

It seems this unit tests for all the issues you'd want to test at the post (accidental 240v installation, reverse polarity, open neutral, open ground) and in those cases will not send power to your RV. In addition, if the voltage is too low/high, it will shut down to reset and if a surge will protect your electronics. While fairly expensive, it seems like an all in one option for testing and surge protection. Am I seeing that right and if so, how the heck does the lock part work? :-)
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Old 07-15-2013, 10:54 PM   #94
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In another thread on surge protectors, I followed a link to this: EMS-PT30C

It seems this unit tests for all the issues you'd want to test at the post (accidental 240v installation, reverse polarity, open neutral, open ground) and in those cases will not send power to your RV. In addition, if the voltage is too low/high, it will shut down to reset and if a surge will protect your electronics. While fairly expensive, it seems like an all in one option for testing and surge protection. Am I seeing that right and if so, how the heck does the lock part work? :-)
We have one of these and like it very much. The "lock part" is only a ring that can be used with a cable-type lock to secure the device from theft. It's aluminum and would be easy prey for a pair of bolt cutters.

Instead of that, I use an extension cord so that the surge protector can remain inside the locked rear compartment of our trailer.
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Old 07-16-2013, 03:06 PM   #95
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I continue to plug this one. (pun intended)

EMS-HW30C

Good protection, useful info from the panel, can't be stolen.
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Old 07-16-2013, 05:15 PM   #96
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I continue to plug this one. (pun intended)

EMS-HW30C

Good protection, useful info from the panel, can't be stolen.
Nice pun! :-)

I think the electronics are the same as the portable one, yes? Definitely advantages to the hard mount but not wanting to muck with the wires, I'm thinking portable. Do I understand correctly that it's pretty much an all in one tester, surge and EMS protector? If so, I'm ready to buy. Small insurance against big losses.
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Old 07-16-2013, 05:47 PM   #97
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Nice pun! :-)

I think the electronics are the same as the portable one, yes? Definitely advantages to the hard mount but not wanting to muck with the wires, I'm thinking portable. Do I understand correctly that it's pretty much an all in one tester, surge and EMS protector? If so, I'm ready to buy. Small insurance against big losses.
Same protections, hard wired or portable. Great unit. Hard wired unit was very easy to install.

1. Disconnect power.
2. Open transfer relay and disconnect 3 wires.
3.Connect those wires to EMS
4. Connect new wire from EMS back to transfer relay
5. Mount remote ( I put mine in the cabinet under the sink)
6. Reconnect power secure in the knowledge that your electrical stuff is protected and no one can steal the EMS.



Not rocket science.
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Old 07-16-2013, 07:32 PM   #98
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Cool - ill be considering these for sure

Still foggy on portable vs fixed?
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