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Old 09-12-2022, 12:29 PM   #15
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One thing that many are not aware of is that the rating on the plugs & receptacles is for peak load. The "sustained load" (30 minutes or longer) rating is 80% of that. If the a/c is running non-stop on a hot day, chances are a 30A plug is handling a constant 24A or thereabouts, so it is in fact working at or near its rated max. The big pins of the plug can handle a lot more, but the connecting surfaces are the weak point (as others have already explained).


I mention this only to make people aware that you should not be thinking "only" when talking about a 20-24 amp load on a 30A plug. If your load is in that range, be on the lookout for overheating outlets & adapters. Even more so if pulling 15-16 amps through a 30A-->20A adapter. Those adapters & plugs rarely have much extra margin built into their rating.
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Old 09-13-2022, 11:14 AM   #16
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Can you explain how the power draw works? My understanding is the A/C draws about 12.5A, if we're running frig and hot water on propane, the only other power used would be for lights and TV, which can't be more than a couple amps. Or am I wrong and the inverter that keeps the battery charged and a small-ish TV draw a lot more than that?


Once I get the surge protector working I should know more - presuming the fix works.
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Old 09-13-2022, 03:32 PM   #17
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Quote:
Originally Posted by Gary RVRoamer View Post
One thing that many are not aware of is that the rating on the plugs & receptacles is for peak load. The "sustained load" (30 minutes or longer) rating is 80% of that. If the a/c is running non-stop on a hot day, chances are a 30A plug is handling a constant 24A or thereabouts, so it is in fact working at or near its rated max. The big pins of the plug can handle a lot more, but the connecting surfaces are the weak point (as others have already explained).


I mention this only to make people aware that you should not be thinking "only" when talking about a 20-24 amp load on a 30A plug. If your load is in that range, be on the lookout for overheating outlets & adapters. Even more so if pulling 15-16 amps through a 30A-->20A adapter. Those adapters & plugs rarely have much extra margin built into their rating.
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Old 09-13-2022, 05:20 PM   #18
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Can you explain how the power draw works? My understanding is the A/C draws about 12.5A, if we're running frig and hot water on propane, the only other power used would be for lights and TV, which can't be more than a couple amps. Or am I wrong and the inverter that keeps the battery charged and a small-ish TV draw a lot more than that?

Once I get the surge protector working I should know more - presuming the fix works.
You are pretty much on-target. Allow about 3-4 120vac amps to power the 12v needs and a tv. But people often underestimate those other amp draws. Or forget the occasional extras. For example, might you want to heat something in the microwave? Have a laptop plugged in? Phone charger? Make a pot of coffee in an electric percolator? Maybe somebody needs a few minutes with a hair dryer? Some of those are miniscule; others run several hundred to as much as 2000 watts. Since you've never had the 30A breaker trip, I presume you do a good job of limiting things like that, but it's really easy for the amp load to creep up to the 24-28 range these days.
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Old 09-13-2022, 10:14 PM   #19
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Yeah, that would be true of us... We don't do coffee or hair dryers, but we do pop stuff in the microwave... About the WORST would be 3 minutes for popcorn, but during that three minutes I can see is being 25 or even 27 amps maybe.......


SO in the end, it all comes down to paying attention - if you're running the A/C DON'T be doing a bunch of other high-draw stuff - just 'cause you're NOT blowing the breaker DOESN'T mean things aren't getting a workout and hot...


BTW: In my original list I COMPLETELY forgot the microwave!
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Old 09-14-2022, 06:02 AM   #20
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I have a cheap amp monitor in my older 30A RV, no power management.. Think it was around $25 on amazon.. Put a sensor on feed wire into panel and it work..

Any way, with my 13.5K new AC running (low fan full cold., the converter on/chg on, TV on, absorb fridge switched to elec. 1520-1660 watts at 118-120v is the norm..
If AC cycles you get a spike 2900-3400 for a second or two..

With the AC on, TV on and solar chging/12v loads are off conv/chg, and fridge is on Propane I see 1280 watts to 1410 depends on temps 11-12 amps..

BUT I have used a 30-20A adapter into a wall recpt.. It got WARM.. a few times.. Melted a wall recept only becasue.. someone plugged stuff into another recpt on same circuit,, breaker held 20A with 15A recpts,, (common in some garages etc)

Just watch your dork ends and adapters of any type, ems, surge, whatever
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Old 09-18-2022, 01:45 PM   #21
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I KNEW this wasn't being weird enough.....................


Got the old cable out of the surge protector.



AND, it had FOUR wires, not THREE. BUT, the three large ones are the normal black, white and green. Then, there's a very small gauge blue wire that goes through the cable and over to a plug on a circuit board.


I've attached some pictures.






I also put in a picture showing a blue wires that run from end-to-end, and connect to a pin on whatever is in the middle of the whole thing.


I'm ASSUMING (which is why I'm asking 'cause I'm usually wrong) this blue wire is either ground or power, but I don't know which.


I'm reluctant to pull the other end of the surge protector apart. Everything is bonded and covered with silicone and there's stuff down there I'd rather not mess up. Any more than I already have.
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Old 09-18-2022, 03:00 PM   #22
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Originally Posted by Gary RVRoamer View Post
One thing that many are not aware of is that the rating on the plugs & receptacles is for peak load. The "sustained load" (30 minutes or longer) rating is 80% of that. If the a/c is running non-stop on a hot day, chances are a 30A plug is handling a constant 24A or thereabouts, so it is in fact working at or near its rated max. The big pins of the plug can handle a lot more, but the connecting surfaces are the weak point (as others have already explained).


I mention this only to make people aware that you should not be thinking "only" when talking about a 20-24 amp load on a 30A plug. If your load is in that range, be on the lookout for overheating outlets & adapters. Even more so if pulling 15-16 amps through a 30A-->20A adapter. Those adapters & plugs rarely have much extra margin built into their rating.
Gary is right (mostly) and absolutely right that people misunderstand or abuse power connections based on their lack of understanding.

PER NEC;
1) Circuits 'rated' at 15/20/30A are NOT DESIGNED TO HANDLE THAT AMPERAGE CONTINUOUSLY. 80% of the rated load can be 'continuous' (which by definition is a load used more than 3 hours in a 24-hour period with no other time specified for max single endurance) and the remaining 20% must be 'intermittent' (less than 3 hours in a 24 hour period. Operating at full rating continuously will heat the cable AND ANY CONNECTIONS unacceptably.

2) Plug ratings are also required to support the cable system rating they are supporting. SO, a 30A plug need only be constructed to support 24A continuously (although most will support more if clean and have the proper socket tension).

3) Socket tension for receptacles is a NEMA standard and rated by the withdrawal tension of the plug. They can be tested using a 'fish scale' type instrument but the force applied must be parallel to the plug contact.

4) A (standard) NEMA 5-15 receptacle/plug (2 vertical flat blades and a round ground pin) is rated for a peak of 15A, only 12A of which may be continuous (using the prior definition of continuous). The fact the NEMA 5-15 plug can be connected to NEMA 5-20 (20A) receptacle, does not mean the plug/receptacle combination can draw 20A (either continuously or intermittently) safely. The 'weakest link' applies. The 15A plug limits the plug/receptacle combination to 15A, only 12A which may be continuous.

5) A '15A' plug is not required to be wired with cable capable of conducting 15A. It may be less.

6) To obtain 20A from a NEMA 5-20 (20A) receptacle, you MUST use a NEMA 5-20 plug (one horizontal, one vertical flat blade, and a round ground) which MAY ONLY be attached to a cable of at least 12AWG or larger (capable of carrying a 20A load). If true, then 20A may be available, only 16A of which may be continuous.
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Old 09-18-2022, 03:58 PM   #23
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Originally Posted by dkperez View Post
I KNEW this wasn't being weird enough.....................


Got the old cable out of the surge protector.



AND, it had FOUR wires, not THREE. BUT, the three large ones are the normal black, white and green. Then, there's a very small gauge blue wire that goes through the cable and over to a plug on a circuit board.


I've attached some pictures.






I also put in a picture showing a blue wires that run from end-to-end, and connect to a pin on whatever is in the middle of the whole thing.


I'm ASSUMING (which is why I'm asking 'cause I'm usually wrong) this blue wire is either ground or power, but I don't know which.


I'm reluctant to pull the other end of the surge protector apart. Everything is bonded and covered with silicone and there's stuff down there I'd rather not mess up. Any more than I already have.
If you have a multimeter that has ohms or a continuity test on it, you can verify what the blue wire connects to. Set the meter to ohms or continuity and attach a probe to the blue wire in the pigtail. Touch each of the terminals in the receptacle end and see which has continuity. Same result should be had by touching probes between blue wire and each of the other 3. Tell you how it's connected.

None of this will guarantee there isn't some electronic device in the receptacle, such as a shunt, used with the blue wire. You could dissect and have a peek?
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Old 09-18-2022, 05:09 PM   #24
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We have experienced warm or even hot plugs over the last 35 years of RVing . Now we are back to a small 30 amp trailer and it’s easy to overload the circuit with a 2Kw hydronic heat and hot water, system as well as air conditioner etc etc etc.

The technology exists now to limit the current based on voltage drop. We frequently charge our electric vehicle in campgrounds as it is our tow vehicle for our little trailer. When we use a TT30 connection the plug has both temperature sensors and low voltage sensors. If the voltage drops to around 111 volts it will drop the charge current from 24 to 18 amps. If it drops to under 109 it will further limit to 12 amps. If the temp rises it will also limit the current. This kind of tech should be easy to integrate into the RV world and at a reasonable cost. (It’s about a 250 dollar device for an EV and it’s standard with every tesla).

Point being, an industrious RV accessory company could do something like this.

Jmho.

John.
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Old 09-18-2022, 06:44 PM   #25
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So can you use Die-electric grease on the prongs for a better connection?
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Old 09-18-2022, 06:53 PM   #26
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Iíve had a few meltdowns, one ruined my plug-in surge protector. As others have said, all do to either lack of spring tension, dirty or wet connections.

I sand and check everything constantly, I use electrical contact cleaner on my gear as well as all park pedestals. I frequently sand and brighten up all my copper contacts, especially during the summer when the AC is cranking and causing the most draw and heat on everything! Itís just part of constant maintenance! I even had my transfer switch burn up due to loose lugs, I solved that but buying an updated PD with Wago connections. They know there an issue, thatís why they went to the Wago connections! They really need to do a recall on all the lug type design. I told them this but they donít care!
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Old 09-18-2022, 07:15 PM   #27
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......... Plus there's a circuit breaker at each end to limit the current to a safe level. .......

Ray

Lots of misconceptions about circuit breakers, how they work, what the protect and HOW THEY TRIP. Trying to draw the maximum from a 30A connection (continuously) is a prime reason for 'succeeding' to operate on small overloads that do some of this kind of damage (but not always necessary). You probably assume that a breaker is a perfect device and will prevent you from getting into trouble as you keep pushing the limits. THEY LIKEY WON'T.

1) THis is a good reference;
https://goodsonengineering.com/wp-co...rMyths_web.pdf

2) The biggest one is that they trip near their rated capacity. AC breakers are both thermal (heat sensitive to trip on sustained, minor overloads but take exponential amounts of time) and magnetic (trip rapidly on a big surge like a short circuit). Typically, small overloads can operate for double-digit minutes to hours before they cause a breaker to trip, allowing connected devices ample opportunity to melt (like connectors).
3)
DC breakers are ONLY thermal and should not be substituted for AC breakers.

4) Fuses operate by heating thill they melt. They heat in a non-linear fashion. Because they generate a lot of heat if operated near their rating and that heat gets conducted down the highly conductive copper wire, it is not uncommon for insulation near a fuse to fail, even at the point of charring.

TBL; Assume that breaker will trip is a 'reasonably short time' (by my definition that means single digit seconds) at around 130% of their capacity.

Second thoughts on the connector;
One of the businesses I was an engineer for was a company that made 'safety interlocked connectors' for the connection of refrigerated containers when not in transit. The EPA will not permit the operation of diesel refrigeration in storage yards (or on ships). There are literally hundreds of thousands of these in operation WW. These are 480V/30A 3-phase connections. What's important is the problem with them WAS just like RV plugs....but no longer. The contact pins failed readily, most got burned off by connecting and disconnecting under load.

The 'safety interlocked connector' was born which includes a receptacle, a molded case circuit breaker, and a mechanism that includes a sensor pin on the ground contact (it's the longest one for a reason). When plugged in, if the plug is pulled out with power applied, the backing out of the ground pin, trips the breaker BEFORE the connector un-mates (a purely mechanical device). When connecting, the circuit cannot be turned unless a plug is fully installed (because the ground pin must press on the safety mechanism. This is a pretty simple mechanical interlock that COULD and SHOULD be used for RV connections.

Lots of different plug types are available.
https://catalog.eslpwr.com/product-c...power-outlets/
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Old 09-18-2022, 08:05 PM   #28
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I found a couple topics about problems with RV plugs, but most seemed to be from situations where line voltage went way down or they were trying to draw more than 30A.


I have a small 5th wheel. 30 amp cable/plug. Ordinary stuff drawing electricity. Inverter that keeps the batteries charged, 13.5 Kbtu A/C. Not much else I can think of off-hand. The hot water heater and refrigerator can run off 120V, but we donít normally do that when using the A/C.


Iíve NEVER had the 30 amp breaker on the power pole blow. Iíve also NEVER had the 30 amp breaker in the trailer blow. Neither. Ever.


Occasionally, weíre too far from the power pole and use a 30A extension, but thatís never caused any problems or melted or done anything strange.


A couple years ago I added Surge Guard Model 34830, 30 amp surge protector. I never had any problem with the voltage shown at any campground, but I read so much about bad power that I bought one.


As I recall, the MOST it ever showed for draw was about 24 amps Ė and that was WITH the frig on 120V.



On one trip, after a few days at a campground in MN, with the A/C on, (water heater and frig on propane) the plug from the trailer was welded into the receptacle on the surge protector. Was a big PITA to get it apart. Surge protector plug was so bad I had to cut it off and toss it. Plug from the trailer was also bad and had to be replaced.


Weíve been using it this year and haven't had any problems 'til recently, but last time out it did the same thing again. Even without the surge protector Ė going straight into the pole, the last time out the trailer plug was discolored and showed melting.


The metal prongs on all the plugs and receptacles look fine Ė no corrosion or crud.


How do I keep this thing from damaging power plugs? Same question for the new receptacle on the surge protector? Is there some magic I'm missing or something I should use on the prongs so they make good contact and don't overheat? Or what?
All that I've seen involve 30amp plugs ruined by using loose and burned 30 amp outlets producing a domino effect. My answer with the 30amp coaches that we've owned, was for installing 50amp plugs in their place.
Problem solved!
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