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Jul 30, 2021 - 4:51:06 AM

banjoy

USA

9849 posts since 7/1/2006

To add to the mix, I've seen old circuit breakers freeze up and fail (rust, corrosion?) and never trip. Whatever repairs are needed, make sure you replace these old breakers too.

Jul 30, 2021 - 11:53:19 AM

dat

USA

31243 posts since 7/26/2006

quote:
Originally posted by overhere
 

AC's are typically only 220-240 volt in residential. no need for neutral. Therefore 2 conductors and green or bare for ground only (2 wire) something like a dryer or something that has a 240-110  will need a neutral...2 plus neutral plus ground.


Ok, nothing to do with a/c systems, more just electrical,   but can you explain how three legs of 270 is called 480v 

Jul 30, 2021 - 11:59:49 AM
likes this

10483 posts since 8/22/2006

Edited by - 5B-Ranch on 07/30/2021 12:01:56

Jul 30, 2021 - 12:11:52 PM

dat

USA

31243 posts since 7/26/2006

Pretty simple wiring, if you get it wrong, it just runs backwards, you don’t have to worry about burning anything up

Jul 30, 2021 - 12:41:32 PM

4356 posts since 12/6/2009

When you ask about 277 or 480 you have to know about transformers and the circuits your trying to feed. I you are talking about single phase 277 or 480 then you have same configuration as 240 single phase... if you use 480 volt single phase to heat 2 wire heater then you only need 2 wires. I’m not sure how you would wire for a heater or cooling circuit needing 3 wires except for cooling when it requires 3 phase for motor circuits (compressor pumps.) then it could requires 3 phase wires. Has nothing to do with 240 volt single phase. They do have 240 volt 3 phase that’s also used for ac compressor wiring or motor wiring....3 phase in any configuration wont be found or in most cases even available to residential power supplies. Mostly commercial/industry, voltage configurations are made through various transformer configurations....Y- Delta etc blah blah.....search the net for information if needed.
We tried once to get 3 phase 277/480 to a small pot pie manufacture company for their walk in freezer systems.. but the power company required a certain amount of KW being in use to even consider it...which the manufacture couldn't meet.

Jul 30, 2021 - 1:36:59 PM

dat

USA

31243 posts since 7/26/2006

Yeah, it’s at work, we have everything three phase, a lot of machines running, I wouldn’t want to see the light bill here

Jul 31, 2021 - 3:59 AM
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4356 posts since 12/6/2009

dat....actually 3 phase powers motors cheaper than single phase and the higher the voltage also the more cheaper to power those motors.....(or 3 ph equipment). so industry is getting use cheaper than you think.
[quick example. 1000 watts 240volts single phase = 5amps used. rounded......1000 watts 480 v delta = 1.2 amps used rounded]

Edited by - overhere on 07/31/2021 04:00:07

Jul 31, 2021 - 6:36:38 AM
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4356 posts since 12/6/2009

Actually what I wrote is incorrect and I apologize for misleading. It is not cheaper to run on the higher voltage although power factor and balance do play a role in cost effectiveness. The real cost savings is in the installation of installing power apparatus to those systems....wire size, service size control systems etc. wiring alone can be a fraction of cost of low voltage systems which make it cheaper.....1000 watts is 1000 watts no matter the voltage. Some power companies do however give better rates for efficiency which is due to higher voltage configurations.

Wire cost as example
[10 horse motor at 240 volt single phase draws 32 amps or # 8 copper @ 45 cents foot. 1000 feet 450 dollars]
[10 horse motor at 480 volt delta draws 10 amps or #14 copper @13 cents a foot. 1000 feet 130 dollars]

Jul 31, 2021 - 6:55:42 AM

dat

USA

31243 posts since 7/26/2006

Would there be much difference on the machines starting amperage? The motors run all day, but I would think the different voltage may be a boost on start up, could be wrong though,

Aug 1, 2021 - 2:55:14 AM

4356 posts since 12/6/2009

Single-phase motors cannot start by themselves, requiring external devices. On the other hand, a three-phase motors can start with the power supply alone, and it can even reverse direction if you switch two conductors with each other.

Aug 1, 2021 - 5:30:38 PM
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Enfield1858

England

128 posts since 8/1/2020

quote:
Originally posted by overhere

Actually what I wrote is incorrect and I apologize for misleading. It is not cheaper to run on the higher voltage although power factor and balance do play a role in cost effectiveness. The real cost savings is in the installation of installing power apparatus to those systems....wire size, service size control systems etc. wiring alone can be a fraction of cost of low voltage systems which make it cheaper.....1000 watts is 1000 watts no matter the voltage. Some power companies do however give better rates for efficiency which is due to higher voltage configurations.

Wire cost as example
[10 horse motor at 240 volt single phase draws 32 amps or # 8 copper @ 45 cents foot. 1000 feet 450 dollars]
[10 horse motor at 480 volt delta draws 10 amps or #14 copper @13 cents a foot. 1000 feet 130 dollars]


There's also the big advantage that things like electric motors are cheaper to build if they run on higher voltages, as the windings can be thinner, making the armature physically smaller, so the motor casing is smaller, bearings are smaller, and so on - savings all the way round.

Aug 1, 2021 - 5:43:11 PM

Enfield1858

England

128 posts since 8/1/2020

quote:
Originally posted by mike gregory

My guess is that anybody who has worked with AC as a business, would be able to diagnose and repair.
I wouldn't want to mess with any voltages higher than it takes to light a lamp.

Although, according to Billy Crystal, in a cop buddy movie with Gregory Hines:
"It ain't the VOLTAGE that kills ya. It's the AMPS!"
So Hines asks: "Well then, how many AMPS are in the third rail??"
Billy's reply:
"Enough to push a TRAIN!"


Exactly, Mike - a point hammered into me when I joined the RAF as a radio mechanic; "Volts jolts - but current kills!"!

For example; you touch the top of a spark plug when the engines running, and depending on whether it's coil ignition or electronic, the voltage will be anywhere from 10-20,000 volts. It'll certainly make you jump, but it won't kill you - there's not enough current.  If, on the other hand, you get yourself across a 220 volt terminal which can supply 13 amps, it's curtains.

Aug 2, 2021 - 3:07:36 AM

4356 posts since 12/6/2009

quote:
Originally posted by Enfield1858
quote:
Originally posted by mike gregory

My guess is that anybody who has worked with AC as a business, would be able to diagnose and repair.
I wouldn't want to mess with any voltages higher than it takes to light a lamp.

Although, according to Billy Crystal, in a cop buddy movie with Gregory Hines:
"It ain't the VOLTAGE that kills ya. It's the AMPS!"
So Hines asks: "Well then, how many AMPS are in the third rail??"
Billy's reply:
"Enough to push a TRAIN!"


Exactly, Mike - a point hammered into me when I joined the RAF as a radio mechanic; "Volts jolts - but current kills!"!

For example; you touch the top of a spark plug when the engines running, and depending on whether it's coil ignition or electronic, the voltage will be anywhere from 10-20,000 volts. It'll certainly make you jump, but it won't kill you - there's not enough current.  If, on the other hand, you get yourself across a 220 volt terminal which can supply 13 amps, it's curtains.


Working with radio power. My Father was a short wave ham operator and built most of his own equipment. When we were little kids we woke one morning to find my father’s hands wrapped in bandages and his forehead wrapped in bandages. My Mom told us he had been doing something to his radio when all of a sudden she heard a bang and a flash and my father was laying on his back about 10 feet across the living room where he had his radio set up. Apparently he had touched the wrong thing and zapped him.....burnt his hands and he hit his head on a coffee table ......so high voltage can kill in that sense.....lol.... but your right it’s not the volts it’s the amps....in certain situations in can take less than 1 amp to kill you....AC . many years ago in hospitals they were finding out that metal hospital beds were attributing to heart failures due to current carrying apparatus for patients and as their body parts touched metal bed frames they completed a ground circuit in some cases...most were less than an amp.....not many but enough to change some thinking around electricity in hospitals.

Ps I like the title Enfield....I have one in my closet a sporterized 1915

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