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Old 12-02-2021, 02:17 PM   #29
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The ups is there for another reason on mine as well. I have a NAS in place to hold lots of stuff. Of course Stuff is held in the cloud as well but the NAS gives me instant access and peace of mind for the most part. A lifetime of pictures and videos are on it. And yes, there is off property/rv storage as well.

Family videos and photos are on the Plex App. Fun to be able to pop up movies and home movies at will.
Yes I have a Synology at home and run it and my core network gear off a UPS will keep internet and nas going for about 30-45 minutes, I want more runtime, so might go for a bigger UPS but probably will do the big inverter and be done with it to run network, tv, computers and lights for a couple hours would be nice and eliminate all the little ups's

I run a Raspberry Pi as NAS in the RV along with router directly off 12v so they always have power unless batteries are dead. Most NAS's and routers can be made to run off 12v either with regulators or many of them actually take 12v directly if you look at their wall warts, and usually doesn't need to be exactly 12v will accept wide voltage range.
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Old 12-03-2021, 08:43 PM   #30
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I'm sure you won't like hearing it, but the Hughes device is not allowed by the NEC. In short it draws more current, dropping everyone else's voltage further.

I've read everything Hughes says, and the NEC on the topic. That's convinced me to never trust anything Hughes says.
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Old 12-03-2021, 09:04 PM   #31
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In short it draws more current, dropping everyone else's voltage further.
I don't understand why would I not be allowed to use an autoformer with a single air conditioner raising its draw by couple amps but my neighbor can run two air conditioners drawing twice the amp from the park? What about using an autoformer with a 13.5k but ac vs my neighbor with no autoformer and a 15k btu ac?

I thought a 30 amp site meant I was allowed to draw up to 30 amps regardless of how its used?

Can I run my air conditioner and a second fan at the same time? That also draws more amps than just the air conditioner alone.

Seems like a silly regulation and makes no technical sense. Obviously the park has poor electric provisioning if the voltage is sagging, maybe the NEC should require RV parks have properly provisioned service rather than banning autoformers.
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Old 12-03-2021, 09:30 PM   #32
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I'm sure you won't like hearing it, but the Hughes device is not allowed by the NEC. In short it draws more current, dropping everyone else's voltage further.



I've read everything Hughes says, and the NEC on the topic. That's convinced me to never trust anything Hughes says.


If you are on a 30 amp circuit you are limited to 30 amps by circuit breaker. Using a Hughes is not going to make you use anything above 30 amps.
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Old 12-03-2021, 09:43 PM   #33
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The core problem is that the park system is overloaded. At that point how much you think can draw is irrelevant. Every added amp makes everything worse.

As for the fine technical points, I won't try to explain them. I rely on the industry experts that write the codes.
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Old 12-03-2021, 11:20 PM   #34
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If you are on a 30 amp circuit you are limited to 30 amps by circuit breaker. Using a Hughes is not going to make you use anything above 30 amps.

Absolutely. What happens is your voltage is boosted while your usable amps are reduced.
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Old 12-04-2021, 11:44 PM   #35
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FYI those numbers on the breaker handles aren't guaranteed, they are "more like guidelines."

Standard breakers are only rated to hold that for up to 3 hours, after that 80% is the rule. But they can also hold more, memory says 10% or so.. Once heat and age enter the picture far less is common!
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Old 12-05-2021, 07:32 AM   #36
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FYI those numbers on the breaker handles aren't guaranteed, they are "more like guidelines."

Standard breakers are only rated to hold that for up to 3 hours, after that 80% is the rule. But they can also hold more, memory says 10% or so.. Once heat and age enter the picture far less is common!
80% rules is pretty generally accepted and no I would not want to load up my 30amp campsite with 30amps continuous, 80% is 24 amps however and that should be fine right?

A single 15k BTU a/c like my Coleman Mach will pull about 1900 watts absolute worse case desert conditions (1600w normal conditions). Using say two auto formers in series from a sagging 90v feed should be right at about 21 amps probably some more due to autoformer losses. I really don't see an issue so long your staying within the 80% rule it really shouldn't matter how I am using that current whether its to boost voltage or just run an extra appliance for some other purpose, should the NEC outlaw using an AC and a second device at the same time in campgrounds?

Autoformers don't back feed anything weird into the grid, they simply pull more current just like running another device would or say the difference between a 15k BTU AC and 13.6k BTU AC. Note the AC itself will pull more current as voltage sags too which is why its not good for the unit, its needs its watts one way or another, auto formers are used to prevent EMS trips and extended the life of appliances by keeping current lower and voltage higher inside the coach.
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Old 12-06-2021, 07:39 PM   #37
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No link between the 80% and autoformer was intended.

My purpose in posting is to inject a little basic knowledge into a discussion showing a vast lack of that knowledge. Such as your 'generally accepted' comment. The 80% rule is code and manufacturer specifications, which darn well better be accepted! And that breakers can hold more than their rated load for a bit, but you can't depend on getting exactly the listed value. (There are more precise devices but they cost more.)

Please also note that no one has contradicted my basic comment. The experts say don't use autotransformers!
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Old 12-06-2021, 08:33 PM   #38
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The experts say don't use autotransformers!
No one seems to to know why, what is the technical explanation for banning an autoformer and not any other device that raises current on the circuit? This rule seems to have no technical basis and is arbitrary unlike the 80% rule.
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Old 12-11-2021, 12:00 PM   #39
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I'm sure you won't like hearing it, but the Hughes device is not allowed by the NEC. In short it draws more current, dropping everyone else's voltage further.

I've read everything Hughes says, and the NEC on the topic. That's convinced me to never trust anything Hughes says.
Can you post the NEC ban....actual verbage used?
Post link to NEC Ban that folks can read?

NEC ban 'auto transformers' OR 'autoformers' ?
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Old 12-11-2021, 12:53 PM   #40
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The NEC code referenced is specifically talking about "Combination Electrical Systems" which are those components that have or use both low and high voltages (such as a 12 volt converter). In those systems an autotransformer is not allowed specifically because there is no isolation coil between the high and low voltages. A standard common transformer has two coils electrically isolated from each other, an autotransformer (autoformer) uses one coil which has the potential to allow high voltage current to go to the neutral\ground connection in certain conditions which is not possible with a standard isolation (two coils) transformer. Therefore the reason NEC specifies this is for safety purposes regarding safely isolating the low voltage 12v and higher voltage 120v. BTW, this code is not referencing autoformers or autotransformers such as the Hughes autoformer and with their designed usage.

BTW, the 80% circuit breaker rule is that the breaker supports 3 hours continuous load at 80% of the rated breakers capacity (24 amps for a 30 amp rated breaker). Not that you can run the full amperage (say 30 amps in this case) of the breaker's rating for 3 hours. How long a breaker can maintain more than 80% of its rating is known as the trip curve, the more amps in use (over the 80%) the less time to break, in other words for a 30a breaker, if you are using more than 24 amps of current then it is simply a matter of time before the breaker breaks, typically 3 hours right at the 80% load but the time is reduced as the amperage is increased. ~CA

Here is a link if anyone wants to read it, if it doesn't go to Part II then scroll down until you find Part II 551.20
https://up.codes/viewer/minnesota/nf...#divider_84_II
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Old 12-11-2021, 09:02 PM   #41
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Here is a link if anyone wants to read it, if it doesn't go to Part II then scroll down until you find Part II 551.20
It's actually 551.72(e), from your link :

Quote:
(E) Connected Devices

The use of autotransformers shall not be permitted. The use of listed surge protective devices shall be permitted.
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Old 12-12-2021, 09:27 AM   #42
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It's actually 551.72(e), from your link :
Yes, it is listed under 551.72(e) and 551.20(e) which means you have to look at what 551.72 and 551.20 are about.

"551.20 Combination Electrical Systems" is referring to just that, systems with combined voltages (in an RV that would be the 12v and 120v specific systems such as the 120v to 12v converter and related components).

"551.72 Distribution System" is referring to the electrical distribution system of an RV Park.

Use of autotransformers are listed elsewhere also, but not related to RV's or RV Park's

In these same conditions you could still use a standard isolation transformer (two isolated coils) assuming all other codes are met, so these sections are not about "not" using any transformer, it is about the safety of using a "single coil transformer" (aka autotransformers) and where not to use them related to RVs and RV Parks. The safety concern is that there is a shared electrical connection to the neutral and ultimately to the ground that a single coil transformer has with the input and output of the transformer sharing a common connection which does not occur in an isolation transformer (common two coil transformer).

In summary, these codes are specific about eliminating the dangers that could occur with a single coil transformer in certain uses. When you plug in an autoformer between the RV park's distribution system and the RV itself, then the autoformer is not part of the RV Park's distribution system nor is it a part of the combination electrical system.

Another way to convey the meaning of these codes is that an autotransformer does "not" provide isolation between the input and output (such isolation is not needed inline with the RV power connection as otherwise w/o the autotransformer there would be a direct connection) and should not be used in installations where the isolation between the input and output is required (for safety purposes). ~CA
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