Power mains question: wire gauge

[DaveC]

Air compressor 1/2 hp motor rated 220v (2-wire, not 3-phase) @ 15A. Distance
from load panel ~100 ft (as the conduit runs).

15A can be handled by 14 gauge, but I'd normally go with 12 gauge due to
start current.

With such a distance, is it recommend to up-scale the wire to 10 ga?

Thanks.

 

[SoothSayer]

Air compressor 1/2 hp motor rated 220v (2-wire, not 3-phase) @ 15A. Distance
from load panel ~100 ft (as the conduit runs).

15A can be handled by 14 gauge, but I'd normally go with 12 gauge due to
start current.

With such a distance, is it recommend to up-scale the wire to 10 ga?

Thanks.

Cant hurt. It would definitely help, in fact. multiple #14s to make
each #10 would work better, keeping each segment electrically separated
except at the nodes, giving a sort of Litz effect. At that gauge, you
can get SPC too (Silver Plated Copper), reducing ohms per foot without
increasing gauge above #10.

And you want a #12 return run for ground fault carriage too.
A single piece would pop a breaker.

 

[Phil Allison]

"DaveC"

Air compressor 1/2 hp motor rated 220v (2-wire, not 3-phase) @ 15A.

** Giant HUH ??

Such a motor normally draws around 3 amps.




.... Phil

 

[[email protected]]

  Cant hurt.  It would definitely help, in fact.  multiple #14s to make
each #10 would work better, keeping each segment electrically separated
except at the nodes, giving a sort of Litz effect.  At that gauge, you
can get SPC too (Silver Plated Copper), reducing ohms per foot without
increasing gauge above #10.

  And you want a #12 return run for ground fault carriage too.
A single piece would pop a breaker.

considered what the skin deepth at 60Hz is?....

-Lasse

 

[Bill]

Air compressor 1/2 hp motor rated 220v (2-wire, not 3-phase) @ 15A. Distance
from load panel ~100 ft (as the conduit runs).

15A can be handled by 14 gauge, but I'd normally go with 12 gauge due to
start current.

With such a distance, is it recommend to up-scale the wire to 10 ga?

There is s thing called "voltage drop". Voltage will drop in a wire
running a long distance, sometimes so much, the device at the end will
not operate!

The amount of voltage drop depends on the voltage, the type of metal
used for the wire (copper / aluminum), the wire size, and the load in
amperage at the end of that wire.

The internet has made this easy for you. Just search google.com for the
words...

Voltage Drop Calculator

 

[DaveC]

Until the motor or compressor is replaced with a larger unit. Then

all bets are off. It's cheaper to do it right the first time. You
could even put a small breaker box by the compressor & run AWG 6 to it,
to power other tools, as needed without starting from scratch.

That's a good idea. I'll talk it over with the owner.

But for now I want to settle on what size conductor to use if it's just to
supply this one compressor.

Thanks.

 

[[email protected]]

Until the motor or compressor is replaced with a larger unit. Then
all bets are off. It's cheaper to do it right the first time.

If it's 1/2HP, now, it's unlikely to grow to >5HP.

You
could even put a small breaker box by the compressor & run AWG 6 to it,
to power other tools, as needed without starting from scratch.

Run several #12s, instead, when needed. It's cheaper.

 

[notme]

Run several #12s, instead, when needed. It's cheaper.

Pull additional #12s in the future? I've had bad experience pulling
additional conductors in a conduit with existing conductors.

If I misunderstand your statement, please try again. ;-)

Thanks.

 

[MrTallyman]

Pull additional #12s in the future? I've had bad experience pulling
additional conductors in a conduit with existing conductors.

If I misunderstand your statement, please try again. ;-)

Thanks.

No. A bundle of a few 12s will make a nice oversized #10.
The finished 'wire' will be stronger and more flexible too.

Of course, the return has to match. So you pull all 7 at once.

Two sets of 3 #12s and one #12 fault return. Seven wires.

 

[[email protected]]

Pull additional #12s in the future? I've had bad experience pulling
additional conductors in a conduit with existing conductors.
Conduit?

If I misunderstand your statement, please try again. ;-)

 

[[email protected]]

I've never seen a 240 volt compressor it a 1/2 HP motor 2 HP is
common, and go on up as the capacity increases.

I've seen a *lot* of 1/2HP motors used for power tools that can be
wired either way.

A local business
recently switched from multiple 2 HP 240 VAC 60 gallon compressors to a
pair of 480 VAC three phase units with 120 gallon tanks that are set upi
to run their entire production line from one unit. It was the old EDCO
factory that Emerson closed a few years ago..

Rather irrelevant.

Cheaper? When did yo go over to the 'Do it any way but right' side?

I always do it the right way. The "right way" depends on the
situation. I guess the "right side" is universal, though, but it's
also right.

It's not cheaper when the extra labor and increased material costs
are added for doing the job more than once. If you didn't size the
conduit for more wire, you'll have to rip it all out & start over.

It's a *lot* cheaper. #6 is a PITA to work with. No thanks!

Then there's the cost of a bribe to get the inspector to look the
other way.

Now you're throwing in random costs.

 

[[email protected]]

Who uses 3KV?

OK, 300K.

 

[Tom Biasi]

OK, 300K.

How about run what you need now with a pull string included?

 

[[email protected]]

On an air compressor?

Sure. Most small fractional horse induction motors can be.

 

[[email protected]]

How about run what you need now with a pull string included?

I think we have a winner!

 

[[email protected]]

Inside your home? Or where you work?

Hey, you never know how big of a compressor you might need.

 

[rickman]

That's a good idea. I'll talk it over with the owner.

But for now I want to settle on what size conductor to use if it's just to
supply this one compressor.

Thanks.

100 feet of AWG 6 will set you back some C-notes. That's an expensive
investment if you don't need it.

Rick

 

[SoothSayer]

100 feet of AWG 6 will set you back some C-notes. That's an expensive
investment if you don't need it.

Rick

What utter idiot suggested #6?

 

[Spehro Pefhany]

100 feet of AWG 6 will set you back some C-notes. That's an expensive
investment if you don't need it.

Rick

It's also a sweaty PITA to pull.. ( I ran some to a manly (for single
phase) compressor and kiln).


Best regards,
Spehro Pefhany

 

[Jasen Betts]

Until the motor or compressor is replaced with a larger unit.

a larger compresser is likely to have a soft start where the pump
compression is releived come on until it's up to speed.