wiring 460v 3 phase

[budco]

My new shop is being built and I'm want to replace my compressor. I found a great deal on an IR but it's 460 volt. It will be about 4 months before I run the wiring to the shop and wire the shop, so it's just adding what's needed to add a 460 line. What I'd like to know what's the difference between wiring 230 and 460 volt.
thx.

 

[wyliesdiesels]

First off if u dont know what youre doing, as evidenced by what u said, then u shouldnt be working with 480v electricity. Its a lot different than 240v.

480v is NOT a DIY voltage.

What is the HP rating on the compressor?

U will need a transformer, a rotary phase converter and then a second panel just to run that compressor.

It will be more expensive than just selling the compressor and buying a single phase 240v unit.

 

[budco]

Not spam, wasn't sure what all was involved. Finally got in touch with the seller and they used it at a commercial warehouse. Thanks for the reply....

 

[Pwrgeek]

If it's a steal buy it and replace the motor. Otherwise the logistics of 480 in a home setting (if you can even get it most utilities won't install a 480 service to a residence) is not worth doing for one device.


Sent from my iPhone using Tapatalk

 

[Dick in Wisconsin]

My parents house was built in 1955 with a ground water heat pump. The compressor used a 7.5hp motor and the fan to circulate the air in the house I think was a 2hp.

The house is wired for 480v three phase power. Separate meter for the three phase power. I know the compressor motor was 480 three phase, blower motor was probably three phase (unsure about the volts). Has a well dedicated to the system, that pump is 240volt, three phase.

Everytime someone came to work on the system and saw the electrical panel and boxes I heard the same thing: "If we need to do anything electrical on this thing, you have a call an electrician."

Replaced the compressor and the blower with a 240volt, single phase Water Furnace. Well pump is still three phase.

 

[wyliesdiesels]

Not spam, wasn't sure what all was involved. Finally got in touch with the seller and they used it at a commercial warehouse. Thanks for the reply....

Sorry. I first thought it was spam then saw u had a few posts already. Sometimes we get people who post outlandish stuff and they only have 1 post. Makes it suspect.

480v is not worth it for someone like u that knows little about it.

It will cost u a lot of money to get it to work because u have no 3 phase. U would need a phase converter, transformer and 480v panel.

The biggest safety issue is the arc flash hazard.

Sell the motor and get a single phase replacement or sell the whole thing.

What is the HP rating?

My parents house was built in 1955 with a ground water heat pump. The compressor used a 7.5hp motor and the fan to circulate the air in the house I think was a 2hp.

The house is wired for 480v three phase power. Separate meter for the three phase power. I know the compressor motor was 480 three phase, blower motor was probably three phase (unsure about the volts). Has a well dedicated to the system, that pump is 240volt, three phase.

Everytime someone came to work on the system and saw the electrical panel and boxes I heard the same thing: "If we need to do anything electrical on this thing, you have a call an electrician."

Replaced the compressor and the blower with a 240volt, single phase Water Furnace. Well pump is still three phase.

Wow! 3-phase 480v service to a house? Thats unheard of!

 

[Dick in Wisconsin]

Wow! 3-phase 480v service to a house? Thats unheard of!

Everyone who knows what it is has the same reaction as you do!

When I finally gave up on the original 1955 system (which I think was based on 1930's/40's technology because a similar system in my Dad's business which was in installed in 1947 had the identical motor and compressor), I tried to get a three phase system from Water Furnace. The local dealer quickly realized what we had and strongly advocated for me, but they just didn't have a three phase system at the time. That was in about 2003.

 

[930dreamer]

If you changed the 3 phase motor to 240v 3 phase you could skip the transformer, what's the compressor hp? Is the compressor motor connectable to a lower voltage i.e. 240 volts?

 

[wyliesdiesels]

If you changed the 3 phase motor to 240v 3 phase you could skip the transformer, what's the compressor hp? Is the compressor motor connectable to a lower voltage i.e. 240 volts?

Still need an expensive converter.

 

[theoldwizard1]

The house is wired for 480v three phase power.

Very unusual to be able to get 3 phase in a residential area. They must be near farms.

 

[theoldwizard1]

Back in "my day", shortly after the dinosaurs, big computers required big power. I'm talking computer cabinets the size of 2-4 double door refrigerators. They had 3 phase running into the cabinet which was immediately split into single phases an used to run various power supplies (multiple 5V@100A supplies). Except for the fans. The fans were HUGE and ran on 3 phase. On a new installation you always had to check the "phase rotation" to be sure that fan was blowing and not sucking !

We had panel boards mounted on top of 3 phase transformers in cabinets that sat on the floor. This way you could make connections under the raised floor using liquid-tight flexible conduit, from the panel board to an appropriate outlet (120V, 208V or 230V-3phase) near your computing equipment. The 208V equipment used L6-** plugs and most of that equipment had multitap transformers inside for use with various voltages from 208v-250V. 3 phase use L21-** plugs.

Very simple. Very straight-forward. Of course everything was wired by licensed electricians.

 

[Norcal]

Came across a bootleg mother inlaw unit attached to a shop behind the house, the shop has a 200A 480Y/277V service most of the unit is supplied from a 15 KVA transformer, but they decided they wanted to change the 2X4 recessed troffers to ceiling fans, they took the hot 277V fixtures down & ran into some problems.


This is the well for domestic water, 480V 3Ø see anything wrong?



There is a seperate 100A service for a manufactured home installed by idiots that failed to use the supplied gasket for the "weatherproof" hub, causing corrosion & losing a leg.

Edit: The exposed PVC does not count, only electrical issues.

 

[930dreamer]

Still need an expensive converter.

Depending on the compressor hp, a simple rotary phase converter could be made cheaply.

 

[wyliesdiesels]

Came across a bootleg mother inlaw unit attached to a shop behind the house, the shop has a 200A 480Y/277V service most of the unit is supplied from a 15 KVA transformer, but they decided they wanted to change the 2X4 recessed troffers to ceiling fans, they took the hot 277V fixtures down & ran into some problems.


This is the well for domestic water, 480V 3Ø see anything wrong?



There is a seperate 100A service for a manufactured home installed by idiots that failed to use the supplied gasket for the "weatherproof" hub, causing corrosion & losing a leg.

Edit: The exposed PVC does not count, only electrical issues.

I dont see a controller or starter unless thats what is below the disconnect.

The BX being exposed to the elements.

What else am I missing?

 

[sberry]

I agree this is not for you. I can fug with all that,,,,, and don't. This is an expensive install for a cheap compressor , buy the right one that work on common residential service.

 

[Norcal]

I dont see a controller or starter unless thats what is below the disconnect.

The BX being exposed to the elements.

What else am I missing?

Furnas starter is located below GE NEMA type one disco, metal flex was allowed at one time outdoors.

 

[TheEquineFencer]

Where are you located to start with? What about checking to see if the 460V motor is reconnectable for 230V and using a VFD that is rated for 1Ph input with 3Ph output? Depending on the HP rating of the motor, that might be a good option. I run both my lathe and Mill off VFDs. One is 2HP the other 3HP.

 

[sberry]

He could but it doesnt make it practical or a great idea especially when there is a good plug and play option.

 

[matt_i]

Couple of problems with phase converters and VFDs for compressor use. While you can surely power a VFD with single phase input and receive 3 phase output, there's a de-rating that gives you 1/3 to 1/2 of the motor HP. Not good for a compressor which is setup for a specific HP motor. The problem is even more gross with a phase converter, even a rotary converter, it will power up idling motors as on machine tools, but a laden motor will struggle to start, if it even does. If the motor does not start and it sits there with a locked rotor, its bye bye motor.

 

[sberry]

It's simply extra complicated equipment not needed. He doesn't already own any of it.

 

[TheEquineFencer]

Couple of problems with phase converters and VFDs for compressor use. While you can surely power a VFD with single phase input and receive 3 phase output, there's a de-rating that gives you 1/3 to 1/2 of the motor HP. Not good for a compressor which is setup for a specific HP motor. The problem is even more gross with a phase converter, even a rotary converter, it will power up idling motors as on machine tools, but a laden motor will struggle to start, if it even does. If the motor does not start and it sits there with a locked rotor, its bye bye motor.

That's news to me. The ones (VFDs) I have are rated for full 2HP or 3HP output with single phase input on both of them. You get what you pay for. I used to have one that would start and run a 5HP motor at full load, it was rated for it, but was only rated to start and run a 7.5HP motor at 50% load.

 

[sberry]

sometimes I got to wonder. a guy gets some solid advice before he commits to something he doesn't even own and is obvious as daylight that isn't a good fit but it must be nearly a compulsion to ,,, well

 

[nadogail]

In my experience, 480 3 phase, was not that much more complicated than 208 3 phase.
I stressed to my students, "120 bites, 277 kicks".

It reminds me of the once popular song "I've got a tiger by the tail". There is very little room for error, but you can shove twice as many amps through the same size wire.

Things like disconnects are both larger and more expensive. I've found used 480 volt equipment like transformers and disconnects are priced very reasonably at industrial salvage sales yards.

We just have to be more careful but 480, like 208, is a manageable risk.

 

[sberry]

while some of it may be technically correct it's poor advice for this poster.

 

[wyliesdiesels]

Furnas starter is located below GE NEMA type one disco, metal flex was allowed at one time outdoors.

O u gave it away. I couldnt tell the pic was too blurry on my phone. Should be NEMA 3.

In my experience, 480 3 phase, was not that much more complicated than 208 3 phase.
I stressed to my students, "120 bites, 277 kicks".

It reminds me of the once popular song "I've got a tiger by the tail". There is very little room for error, but you can shove twice as many amps through the same size wire.

Things like disconnects are both larger and more expensive. I've found used 480 volt equipment like transformers and disconnects are priced very reasonably at industrial salvage sales yards.

We just have to be more careful but 480, like 208, is a manageable risk.

no ampacity of wire doesnt change with voltage. The correct unit of measure would be watts. U can carry more watts with higher voltage.

 

[walrus]

Furnas starter is located below GE NEMA type one disco, metal flex was allowed at one time outdoors.

It never rains in California

 

[wyliesdiesels]

It never rains in California

What u talkin' about willis? Rained on and off all last week!

 

[nadogail]

Thanks for the correction, I was thinking of power as opposed to current flow, and trying to keep my explanation in simple terms.

I should have said:
You can shove twice as much power through the same size wire by doubling the voltage.

 

[wyliesdiesels]

Thanks for the correction, I was thinking of power as opposed to current flow, and trying to keep my explanation in simple terms.

I should have said:
You can shove twice as much power through the same size wire by doubling the voltage.

Sounds better than what i said. English isnt my best subject!

 

[wagspe208]

IF he is going to buy a new motor... why on earth would he buy a 3 phase?
wAGS

 

[sberry]

The OP did good by asking BEFORE he bought the unit. So many are outright blinded by what seems like a deal to start, a big reason these are so cheap.

 

[Dragfluid]

In my experience, 480 3 phase, was not that much more complicated than 208 3 phase.
I stressed to my students, "120 bites, 277 kicks".

It reminds me of the once popular song "I've got a tiger by the tail". There is very little room for error, but you can shove twice as many amps through the same size wire.

Things like disconnects are both larger and more expensive. I've found used 480 volt equipment like transformers and disconnects are priced very reasonably at industrial salvage sales yards.

We just have to be more careful but 480, like 208, is a manageable risk.

Wouldn't another way be: "120 sits there waiting to bite, 277 jumps out and bites!"

 

[nh_yota]

A little off topic...but...

Although it's rare for residential service in the rest of the country, it is not uncommon to find 3 phase 240v service installed in older houses in the hotter regions of this country. In the early days of residential air conditioning, the compressors were mostly 3 phase so if you wanted a/c in your house out in Arizona (for instance), your utility would provide either true 3 phase service like they would for a business, or a separate 3rd leg from the pole that piggybacked onto a split-phase panel via a delta breaker for the compressor circuit.

 

[nadogail]

Wouldn't another way be: "120 sits there waiting to bite, 277 jumps out and bites!"

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"

 

[wagspe208]

IF he is going to buy a new motor... why on earth would he buy a 3 phase?
wAGS

Uh, anyone?
Wags

 

[matt_i]

That's news to me. The ones (VFDs) I have are rated for full 2HP or 3HP output with single phase input on both of them. You get what you pay for. I used to have one that would start and run a 5HP motor at full load, it was rated for it, but was only rated to start and run a 7.5HP motor at 50% load.

As you correctly state, one must look in the VFD specs carefully to see if any derating on single phase input is required. I also have a 5hp VFD with full rated capacity from single phase input but it takes some searching to find one that meets these specs.

Working up the control circuit and programming the parameters is another set of challenges that have to be overcome. My main point is that its not a fully automatic modern phase converting device. It needs some selection, and then integration.

 

[SD Joe]

Most of the motors that we sell are tri voltage 208-230/460. There are diagrams on the inside of the junction box cover. I'm not an electrician but it sounds like you are asking for a lot of grief with that compressor.

 

[wyliesdiesels]

Uh, anyone?
Wags

Who suggested doing that?

Most of the motors that we sell are tri voltage 208-230/460. There are diagrams on the inside of the junction box cover. I'm not an electrician but it sounds like you are asking for a lot of grief with that compressor.

Yes many motors are. But if thats the case he would still need a phase converter.

 

[budco]

I didn't mean to start all this, ,was just wondering what needed to be done to use the compressor. I didn't buy it, was checking into it first. I was looking for a nice used before I go out and buy new. Thanks for the responses, most of them anyways....

 

[sberry]

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.