The explanation is that 70% utilization is assumed.
Sounds like a utility thing, as they do what they want. NEC Table 551-73 gives demand factors for site feeders and service-entrance conductors for RV parks. Demand factors vary from 1.0 for a single site to 0.41 for 36 or more sites. But the utilities don't follow the NEC.
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Sounds like a utility thing, as they do what they want. NEC Table 551-73 gives demand factors for site feeders and service-entrance conductors for RV parks. Demand factors vary from 1.0 for a single site to 0.41 for 36 or more sites. But the utilities don't follow the NEC.
I did get the impression that the number was their policy.
Can you explain how a 25kva transformer can handle 400amps of 240v?
The explanation is that 70% utilization is assumed. <snip> but they called it a 45 amp continuous load, and said that I was actually in violation of electric standards as I am pulling up to saturation point constantly.
The load is only continuous if it's running at full load for 3 hours or more, at least according to the NEC. If compressors are cycling and the clothes dryer shuts off, it's not continuous.
Quote:
Originally Posted by redbaron73
Can you explain how a 25kva transformer can handle 400amps of 240v?
I wish I could. The NEC assigns 10-12 sites a demand factor of 50%, but you're getting something like 25%.
In the past, when requesting intermediate voltage wiring run on new poles plus a transformer for very large, stationary equipment and support facility, the utility has always supplied a transformer roughly 1/2 the kVA value we requested and nothing would move them to change that.
Transformers can usually handle a lot more current than their continuous or nominal rating for short times, but push enough through them and the magnetics saturate and you don't get any more. That happened to my FIL at his house where the transformer served too many residences for its capacity and everyone was getting severe voltage sag with A/C's running, including his RV roof A/C. Rather than break up the houses into two groups, they just upsized the transformer, and all is right in the world now.
I wish I could. The NEC assigns 10-12 sites a demand factor of 50%, but you're getting something like 25%.
In the past, when requesting intermediate voltage wiring run on new poles plus a transformer for very large, stationary equipment and support facility, the utility has always supplied a transformer roughly 1/2 the kVA value we requested and nothing would move them to change that.
That is exactly what I am seeing happen here. I am building on property behind the RV park going in. I want 4FHU sites, 50A 240/120V RV electric, plus 200A service for the house.
The distribution designer for residential got offended when I questioned 25kva. So I tried again with the RV parks commercial designer. That is when he informed me that 10 RV sites are served by a single 25Kva transformer. I had a long dialog with him about how much amps these RVs use, and he shrugged, saying that they will all over deliver and it wont be an issue.
I did ask about autotransformers. He had no idea what I was talking about, but did say that new code is very slow to be adopted, sometimes decades.
I thought it was stated earlier that Hughes Autoformer is NOT an auto transformer.
Your statement sounds like it is.
I do understand that they have improved their device above any other on the market. I am just trying to determine if we are talking "Apples" and "Oranges"
Or "Red Delicious" vs "Granny Smith" apples.
I looked up the patent for the Hughes autoformer. It is an auto transformer.
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Paul, Christy and Leap
2017 Dutch Star 4018, 2021 Jeep Wrangler
The NEC only covers hard wired devices--otherwise they would have to be testing any item that gets plugged in. So a plug in autoformer is not prevented by anything in the code.
I made no such claim, I was explaining who writes the Code and how it is adopted.
Devices with plugs are either UL "Listed" or not. Discussing the process for getting a product Listed is a slippery slope and most likely not germane to this topic.
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2005 Four Winds Majestic 23A
“To the world you may be one person; but to one person you may be the world.” - Dr Suess
Or to a memorial of Nicola Tesla (a real genius), or Tom Edison (a guy who hired geniuses and then shafted them on pay), or George Westinghouse (a guy who duplicated Edison's behavior).
If your Newmar is amphibious I suggest stops in Bavaria - Georg Ohm; England - Lord Kelvin & Isaac Newton.
Let us know how the rig handles the Big Pond!
__________________
2005 Four Winds Majestic 23A
“To the world you may be one person; but to one person you may be the world.” - Dr Suess
Newmar Owners Club Appalachian Campers Freightliner Owners Club
Join Date: Feb 2017
Location: Midlothian, VA
Posts: 4,774
I’m setting up an Amnesty drop off where you can surrender your electrical contraband. Please include your box and receipt if available to aid in processing. You’re welcome.
Today’s To Do List;
1)Start my class action law suit against Corey and Neal for illegal and unauthorized use of my allotted sunshine.....(until I can add solar)
2)order the Hughes hard wire kit for my newly purchased Autoformer so I can too can be a fugitive. Sounds like fun.
Tom
Linear Mode
