wiring 460v 3 phase

[Dragfluid]

I don't think so.

If you are on a ladder changing out a ballast in an office bay and working with the lights on because people are working in their cubicles and you somehow get across the 120, you get a bite.

If the lighting is 277, that same contact has the possibility of making you jump so violently, you just might get knocked off that ladder.

That is why I preached "120 bites, 277 kicks"

What I was getting at was, the 277 will arc out at you if you're grounded well. No physical contact needed. No personal experience, just going by what another sparky told me years ago.
Not true?

 

[nadogail]

What I was getting at was, the 277 will arc out at you if you're grounded well. No physical contact needed. No personal experience, just going by what another sparky told me years ago.
Not true?

Apparently, I have opened a "can of worms" writing about changing 277 volt ballasts while energized.

First, please keep in mind that electricians can be compared to pilots, "There are old pilots, and there are bold pilots. There are very few old, bold pilots."

Be aware of just what you are getting your self into. Do not be well grounded while working, that is what fiberglass ladders and rubber soled safety shoes are for. Try to work with only one hand, so as to remain something like the bird perched on a live wire.

If possible, avoid working "HOT"!

The electricians working with hot sticks on energized power lines are different from the rest of us.

 

[nsula_country]

I'm sure that the OP has ran away from this deal by now. If not, and if it's less than 10hp, he could replace the motor and starter... But that's not going to be cheap!

On another note about 3 phase in residential... I know of some of the older, larger houses in Shreveport have 3 phase service.

On the farm we were part of a rural electrification project in the 50's and my grandfather offered for the transmission line to cross the farm. In return, we got 3 phase 240v. Dad has a 400a 3 phase service to his shop that also feeds their house (200a 1 phase sub panel). And we have a 200 or 225 amp service at the barn that also feeds my grandmother's house.

My grandmother's electric heat (25kw?) and air conditioning (6.5 ton) are both 3 phase. I believe the attic fan is also 3 phase. In the barn we have a 30 hp hammermill for grinding feed. If the electric range or heat is on and you hit the starter on the mill, BOOM! there went the main fuses!

CT

 

[wyliesdiesels]

Man no way I could stand having my house fed from a dirty delta supply!

 

[Dragfluid]

Apparently, I have opened a "can of worms" writing about changing 277 volt ballasts while energized.

First, please keep in mind that electricians can be compared to pilots, "There are old pilots, and there are bold pilots. There are very few old, bold pilots."

Be aware of just what you are getting your self into. Do not be well grounded while working, that is what fiberglass ladders and rubber soled safety shoes are for. Try to work with only one hand, so as to remain something like the bird perched on a live wire.

If possible, avoid working "HOT"!

The electricians working with hot sticks on energized power lines are different from the rest of us.

Hugh?
No,,,,,,,,,, no worms. Not even any eggs.
Just the need to learn new things.

 

[Norcal]

Here is a link to photos of a now prohibited Delta Breaker.

http://www.electrical-contractor.ne...cs/152376/The_Elusive_Delta_Circuit_Brea.html

 

[TheEquineFencer]

If I had a sharp eye and was a power shopper and the market was there I got nothing against used but I am not a compulsive type figures I need to save everything I run across. These conversions have their place but unless you want a project all it's own are not well suited for most people. As i said, I can and dont.
It adds up fast and one thing usually leads to another. I live a rural area, There are more resources than ever before but it's still problematic. I like something I can plug straight in to the wall with modest power demands.

As to the OP, please don't take offense, you did good asking before buying it. If you really don't understand 3 phase and "how to make things work" leave it alone. If you understand single phase power and can get a SUITABLE replacement motor for that compressor and it's still cost effective, go for it.

A buddy of mine went through the same thing....after three motor changes he finally got it right. Turns out, utility didn't supply him with the correct size/amperage overhead wire for the loads he was running, he had a heck of a voltage drop at start up, eventually cooking the motors. A lot of the time, there's more to look at, than what you think you're looking at.

 

[wyliesdiesels]

Here is a link to photos of a now prohibited Delta Breaker.

http://www.electrical-contractor.ne...cs/152376/The_Elusive_Delta_Circuit_Brea.html

Holy cow! That was way before my time. And Ive never ran into one of those. Thats insane!

Hows that particular forum? Looks like it doesnt get much traffic. I see your post count is low...

 

[Slowgsr]

Apparently, I have opened a "can of worms" writing about changing 277 volt ballasts while energized.

First, please keep in mind that electricians can be compared to pilots, "There are old pilots, and there are bold pilots. There are very few old, bold pilots."

Be aware of just what you are getting your self into. Do not be well grounded while working, that is what fiberglass ladders and rubber soled safety shoes are for. Try to work with only one hand, so as to remain something like the bird perched on a live wire.

If possible, avoid working "HOT"!

The electricians working with hot sticks on energized power lines are different from the rest of us.

Up here it's 347/600.

Much more fun to work live. Or when a transfer switch blows up.

 

[Pwrgeek]

The main issue with 277/480 is twofold. First at 277 if you grab it you are probably not going to be able to let go. Second 480 is the start of non-contact voltage levels. A 480 circuit will "jump" about half an inch in clean air, further in dirty (smoke, dust, etc) air. That means that all our "just don't touch it and you'll be fine" work methods go out the window and we have to start considering actual approach distance. Overall 277/480 is something that no hobby electrician should be messing with. Leave it to the pros.

 

[Dragfluid]

Thanks for the info, Geek!

 

[TheEquineFencer]

I didn't know that, I thought 660V was the end of the "low voltage".

 

[Norcal]

I didn't know that, I thought 660V was the end of the "low voltage".

600 volts and less is low voltage, 601 volts & up is medium voltage, not sure at the point where it is considered high voltage.

480 volts is not a DIY voltage, the arc flash during a fault is severe enough that IMO, your better off not surviving.

 

[malibu101]

600 volts and less is low voltage, 601 volts & up is medium voltage, not sure at the point where it is considered high voltage.

480 volts is not a DIY voltage, the arc flash during a fault is severe enough that IMO, your better off not surviving.

I too wondered that before as where I work we have 12,470 volt primary feed and it is called medium voltage.
I stole this from Google-
"Voltages 600 V and below are referred to as “low voltage,” voltages from 600 V-69 kV are referred to as “medium voltage,” voltages from 69 kV-230 kV are referred to as “high voltage” and voltages 230 kV-1,100 kV are referred to as “extra high voltage,” with 1,100 kV also referred to as “ultra high voltage.”

 

[nsula_country]

Man no way I could stand having my house fed from a dirty delta supply!

And backup power is from a 3ph 25kw Winco PTO generator!

CT

 

[Pwrgeek]

In the utility world 600V and less is low voltage. 601V - 50kV is medium voltage. 50kV - 138kV is High voltage. 138kV - 345kV is EHV. Above 345kV is UHV

 

[mjoekingz28]

I don't think so.

If you are on a ladder changing out a ballast in an office bay and working with the lights on because people are working in their cubicles and you somehow get across the 120, you get a bite.

If the lighting is 277, that same contact has the possibility of making you jump so violently, you just might get knocked off that ladder.

That is why I preached "120 bites, 277 kicks"

So 120 can cause you to jerk your hand away?


I hate to say, but in high school we went to the New Orleans museum. There was a machine that let you feel like you were shocked by an electric eel. I jerked my arm back so hard and hit a girl in the face.

 

[mjoekingz28]

Also, I have heard of electric fences that will hold on to you.

What conditions are present for this to occur?

I am guessing it paralyzes your nervous system and you become numb.

It is sad that we are using this from stun guns to electric chairs. Not humane, slip me a mickey, guillotine, or knoose anyday over this haphazard nasty, bullfrog, heaping sack of stuff

 

[malibu101]

Also, I have heard of electric fences that will hold on to you.

What conditions are present for this to occur?

I am guessing it paralyzes your nervous system and you become numb.

It is sad that we are using this from stun guns to electric chairs. Not humane, slip me a mickey, guillotine, or knoose anyday over this haphazard nasty, bullfrog, heaping sack of stuff

I've heard, but I don't know for a fact that electric makes your muscles contract.
If that is true; What muscles contract? All of them?
If your bicep contracts, your arm curls up.
If your tricep contacts, your arm goes out.
If both, are you "locked"?

Not taking into account your heart muscle, nervous system, burns, and all the other nasty things that go with an electric shock.

Does AC or DC make a difference?

 

[wyliesdiesels]

There was a debate on here awhile back about which type of electricity is worse.

 

[Slowgsr]

just make sure the apprentice has a 2x4 ready

 

[Dragfluid]

So 120 can cause you to jerk your hand away?


I hate to say, but in high school we went to the New Orleans museum. There was a machine that let you feel like you were shocked by an electric eel. I jerked my arm back so hard and hit a girl in the face.

Did you wind up dating her later on?

Also, I have heard of electric fences that will hold on to you.

What conditions are present for this to occur?

I am guessing it paralyzes your nervous system and you become numb.

Growing up on a farm for 20 some years, I had many "opportunities" for making contact with the electric fence.

Let me assure you, I was able to let go, every single time!

 

[TheEquineFencer]

Also, I have heard of electric fences that will hold on to you.

What conditions are present for this to occur?

I am guessing it paralyzes your nervous system and you become numb.

It is sad that we are using this from stun guns to electric chairs. Not humane, slip me a mickey, guillotine, or knoose anyday over this haphazard nasty, bullfrog, heaping sack of stuff

Used to there were no laws governing fence chargers, some people were running live 120V+ constant to a hot wire and a light bulb as the resistor. Yes, that can grab you and you cannot let go in the right situations.

I can say from personal experience, including just recently sticking my finger on the broken hot wire coming straight off the charger of a Gallagher fence charger, it does not "paralyze" you. But the owner of the fence charger I was talking to on my cell phone asked "what happened?" After regaining my composure, I told him I was just verifying that the charger was working and that he did not need to buy another one. His wife, that was standing beside me, jumped when it arced to my finger. You tend to feel the "Arc" right before the thought "WTF WAS I THINKING?" flashes through your mind.

What it does do is make you jerk whatever body part you touched it with away ASAP. It causes your **** hole to pucker the point you think your nuts may have got sucked in there along with your underwear, pants and wallet. It causes short term memories of the last time you did something stupid like that. It also increases long term memory for the ones that saw you do it, to remind you to be careful when you are near them and an electric fence.

 

[nadogail]

Back in the day, we were all required to see the film "120 Volts, The Deadly Shipmate" that was possibly the most contrived hoaky safety film ever.

There were more electrocutions from 120 than from all other voltages combined.

 

[TheEquineFencer]

Back in the day, we were all required to see the film "120 Volts, The Deadly Shipmate" that was possibly the most contrived hoaky safety film ever.

There were more electrocutions from 120 than from all other voltages combined.

https://archive.org/details/MN8990115VoltsDeadlyShipmate1960
Was it this one?

 

[Pwrgeek]

I've heard, but I don't know for a fact that electric makes your muscles contract.
If that is true; What muscles contract? All of them?
If your bicep contracts, your arm curls up.
If your tricep contacts, your arm goes out.
If both, are you "locked"?

Not taking into account your heart muscle, nervous system, burns, and all the other nasty things that go with an electric shock.

Does AC or DC make a difference?

Thanks to the lax safety culture of colleges of yesteryear we have the answers to these questions.

AC vs DC: AC is more dangerous. The human body runs on AC (about 50hz for the heart). Therefore the AC current required to cause fibrillation (and shortly thereafter death) is about 1/4 that of DC.

Any muscle that conducts an electric current of above about 1mA will contract. So therefore if the shock is going from your hand that grabbed the conductor to your foot that is grounded all of the muscles in your arm, chest, abdomen, and leg will contract.

The let go threshold for humans is about 25mA (maybe more maybe less depending on the individual). The resistance of the human body with dry skin is about 100,000 ohms. If you have any sweat on your skin that value goes down by between a factor of 10 and 100. That's one of the reasons why 240V and less is generally considered safer than say 480. At 240 if you grab an energized conductor your going to conduct somewhere between 2 and 20 mA depending on how recently you cleaned your hands and changed your socks. At those levels you probably will be able to let go. Anything higher probably not.

As for why electric fences sometimes grab they are generally designed to put out pulses (usually 1 per second for about 1/10th second) of about 20 mA. This is so that they have the desired effect on livestock (which have much thicker skin than humans) while not hurting any human that comes in contact.


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[TheEquineFencer]

Thanks to the lax safety culture of colleges of yesteryear we have the answers to these questions.

AC vs DC: AC is more dangerous. The human body runs on AC (about 50hz for the heart). Therefore the AC current required to cause fibrillation (and shortly thereafter death) is about 1/4 that of DC.

Any muscle that conducts an electric current of above about 1mA will contract. So therefore if the shock is going from your hand that grabbed the conductor to your foot that is grounded all of the muscles in your arm, chest, abdomen, and leg will contract.

The let go threshold for humans is about 25mA (maybe more maybe less depending on the individual). The resistance of the human body with dry skin is about 100,000 ohms. If you have any sweat on your skin that value goes down by between a factor of 10 and 100. That's one of the reasons why 240V and less is generally considered safer than say 480. At 240 if you grab an energized conductor your going to conduct somewhere between 2 and 20 mA depending on how recently you cleaned your hands and changed your socks. At those levels you probably will be able to let go. Anything higher probably not.

As for why electric fences sometimes grab they are generally designed to put out pulses (usually 1 per second for about 1/10th second) of about 20 mA. This is so that they have the desired effect on livestock (which have much thicker skin than humans) while not hurting any human that comes in contact.


Sent from my iPhone using Tapatalk

FWIW, 10,000V is the most an electric fence can legally put out in the USA.