Why can't i run my home @ 480V 3ph like a factory? Won't i save $$$, that's why they do it right?


I've had this Q repetively and am wondering how the rest of you field it


[This message has been edited by sparky (edited 08-03-2001).]

Do you work in an industrial area?

[QUOTE]Originally posted by sparky:
[B]Why can't i run my home @ 480V 3ph like a factory? Won't i save $$$, that's why they do it right?


I've had this Q repetively and am wondering how the rest of you field it



Never had anyone ask that but here are few reasons of why not that I can think of.

480 3Ø was designed for heavy power. 277/480 was designed for heavy power/ heavy lighting. Residential areas don't need such power.

They would have to buy/maintain a stepdown trans. Would have to worry about there A/C single phasing if one leg was out. The cost of such an installation would be prohibitive to the savings involved if any. A utility is not going to provide 480 to a residence. There again the cost would also be prohibitive to the utility because the revenue generated from that customer would take a long time to pay for installation and maintenance. 480 fires(faults) don't just go out. They keep burning.

Well theres a few ideas you can throw at them next time they ask.

If I think of more I'll let ya know.

I've been thrown that one a bunch of times too. Most of the time they're under the impression that their power bill would be 1/4 the price, since 480 volts draws 1/4 the current of 120 volts - that's when I take a deep breath and collect my thoughts
Sure would like to find the guy / guys spreading this trash and send them back to their Planet of origin

So, after covering the 'ol "wattage is wattage" scenario to some degree, the next Q is almost always the "Why can't I have 480 VAC 3 Ph at my house?", with the trailing addendum Q of "That's why big companies use it, right?"

Since this is a no-win situation to explain and by this time your set up for failure, because you are not copletely agreeing with the bunk baloney - plus you have unknowingly insulted the person's tech mentor [cross out tech mentor and add the person[s] responsible for spreading the bull poo-poo electrical tech], here's one way to settle it concisely.

Give them these examples:
1:Industries use high horsepower machines which are normally running all day, night, or both.
2: Those loads are commonly located over 100 feet [wire length] from the service equipment - not to mention the transformer,
3: They pay the same as any customer - KWHs! [unless bad PF penalties are included, then they pay MORE!!!],
4: Not very many 480 VAC television sets, VCRs, Home Audio Systems, Refrigerators [residential use], PC power supplies, Vacuum sweepers, decorative lights, residential washers/dryers/irons, hair blow dryers, [you get the hint] are made that I know about. Typically when someone plugs these devices directly into 480 VAC, they run for a minimal time before all the smoke flows out of it - then someone has to sweep up the smoke!
5: 120 VAC is already a high enough voltage to ground for me! Maybe daredevils, thrill seekers and stunt persons with death wishes would enjoy living around a higher voltage to ground, not me.
6: Equipment for systems above 150 VAC to ground / 300 VAC L-L is large and expensive,
7: I could never run the amount of equipment at one time which would benifit from a 480 VAC system [nor could I afford to buy it],
8: The only thing I would have which uses 3 phase power would be a CNC machine, or maybe a big as* surfacer! Once again, there's not too many 3 phase hair blow dryers used in the common person's home,
9: The Utility company's Design Engineers would be laughing so hard at this request for a residence, they would certainy distribute an interoffice/WAN E-Mail joke message to the entire staff about this, and include your name, customer info, plus a possible picture [real photo or cartoon].

Some of these examples are extreme, but gives you enough "ammo" to fire back with.

It can be easilly summed up in one word: "Why???"

Scott SET

lol!
good posts!
i have not found a one sentence comback myself....

Most of the time, I tell them they are paying for power, which I describe to them as amps times volts (I know better, but they don't). When you double the voltage the current drops in half & the answer remains the same.

If I'm feeling cantankerous, I tell them it's a Republican conspiracy to keep the working man down while he subsidizes big business electrical rates.

ouch!

The cost would be prohibitive, if no 3-phase is in the area, they,in my case OE would have to install the three xfmrs, and special permission would have to be given as far as I know, residential doesnt have any 3-phase loads, any 240 volt equipment would not run as effieciently on 208 as on 240, ie water heaters, AC would have to be special, it just isnt practical to use 3-phase in residential.
As I said up the street from there is one home that has three xfmers and one 4-wire service going to the house, how they got it I havnt a clue, because it is very unusual.

I understand some of these larger houses being built these days are getting 3 ph services

This isn't something that I get asked, but then we have only 240/415V and not the variety of systems you use.

I do sometimes get asked to explain 3-phase, though. Except for isolated single properties, all domestic distribution is 3-ph 4-w wye with homes tapped off one phase, so in rural areas with overhead lines I sometimes get the question: "Why are there four wires up there?" Some folks who work in commercial buidings and see the 415V stickers ask how 415 relates to 240V.

I've found that many people can understand the concept of a "back-to-back" arrangement like your domestic 120/240, but start mentioning the sq. root of 3 and they're lost.

In my area, the utility helps me with that question. They don't allow 3 phase to residences, they charge a premium for installing the extra xfmrs and the connection, and they charge a monthly premium for having it. That usually handles it. Two words- "costs more" does it.

I'm not sure what my local PoCo's response would be to a request for residential 3-phase. I don't THINK there's a specific policy against it, although I don't doubt the installation charge would be higher. With 1-ph 240V 100A now standard for new services, most folks have ample power for their needs.

About the only place normally to see 3-ph in a vaguely residential application is a large guest house. The IEE doesn't like the idea of the (eek!) "general public" getting close to 415V, so they specify that all recepts. in each room should be on the same phase.