Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 06-05-2012, 12:17 PM   #1
Newbie
 
Join Date: Jun 2012
Posts: 6
Share |
Default

Advice for my new toys!


I just purchased a new CNC table and compressor and I could use some help with the wiring. I was an apprentice for a few years so Im not completely numb on this subject. I should mention an electrician came and quoted me $800 to do this, so thats why Im here. 80 gallon compressor= 30 amps and the plug on the new plasma cutter is a 50 amp 220. The electricain said he was going to pull 4 #8 wires "45ft" into a deep J box with a 220 outlet for the plasma cutter and then run a whip over to the compressor. My question is, will #8 wire be ok for the#50 amp plasma outlet, or should I go with #6? Will this all fit into 3/4 conduit including a ground wire for each as well?What size should the grounds be? I was planning on installing one 60 amp and one 30 amp disconnect switch next to the machines since the breaker box is at the other side of the building. Could use some advice here, I'm not sure if what this guy was saying will be enough for what I'm doing? Thanks for the help
frodin1 is offline   Reply With Quote
Old 06-05-2012, 02:27 PM   #2
Newbie
 
Join Date: Jun 2012
Posts: 6
Default

Advice for my new toys!


Could somone tell me how many #8 wires are permited in 3/4" EMT at 50 ft? I think it's only four but not sure?
frodin1 is offline   Reply With Quote
Old 06-05-2012, 02:30 PM   #3
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Default

Advice for my new toys!


Post links to the spec's for your loads.
Yoyizit is offline   Reply With Quote
Old 06-05-2012, 02:36 PM   #4
Newbie
 
Join Date: Jun 2012
Posts: 6
Default

Advice for my new toys!


I'll see if I can find something. Im going by what was on the labels.
frodin1 is offline   Reply With Quote
Old 06-05-2012, 02:48 PM   #5
Newbie
 
Join Date: Jun 2012
Posts: 6
Default

Advice for my new toys!


Link for the compressor. I do know the label says 230 volt on the pressure switch: http://www.tractorsupply.com/ingerso...0-gal--3496129
Link for the Plasma : http://www.lincolnelectric.com/asset...8-1/e11300.pdf
I don't really need a disconnect for the plasma I guess since its getting plugged in. But the compressor does get hardwired. My run is 50ft MAX its more like 45ft. from box to box. Im not sure if the 8 wire will be sufficient, nor if it will fit in 3/4 emt.
frodin1 is offline   Reply With Quote
Old 06-06-2012, 11:55 AM   #6
Newbie
 
Join Date: Jun 2012
Posts: 6
Default

Advice for my new toys!


thought this may help others: http://www.westernextralite.com/resources.asp?key=47
frodin1 is offline   Reply With Quote
The Following User Says Thank You to frodin1 For This Useful Post:
goosebarry (06-06-2012)
Old 06-06-2012, 12:11 PM   #7
Sparky
 
Join Date: Mar 2011
Location: Central Florida
Posts: 683
Default

Advice for my new toys!


Max fill on #8 THHN in 3/4" EMT is 6
Techy is offline   Reply With Quote
Old 06-06-2012, 05:27 PM   #8
E2 Electrician
 
stickboy1375's Avatar
 
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 4,236
Default

Advice for my new toys!


Air Compressor break down....

5 HP 240V Motor :
Table 430.248 gives us a FLC of 28 amps
Branch Circuit size is to be no smaller than 125%
FLC 28 x 1.25 = 35 amps, Table 310.16 tells us #10 AWG is good for 35 amps at 75*C....

Now for Short circuit and ground fault protection....
For an inverse-time breaker: 28AŚ2.5 =70A breaker....


I would stick with the cord and plug for the plasma cutter....#8AWG, and 50 amp receptacle.

As far as the pipe line, I would install a 1" conduit to a jbox for the receptacle, then pipe over to a disconnect for the air compressor...

Last edited by stickboy1375; 06-06-2012 at 05:38 PM.
stickboy1375 is offline   Reply With Quote
The Following User Says Thank You to stickboy1375 For This Useful Post:
electures (06-06-2012)
Old 06-06-2012, 06:24 PM   #9
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,513
Default

Advice for my new toys!


Quote:
Originally Posted by stickboy1375
Air Compressor break down....

5 HP 240V Motor :
Table 430.248 gives us a FLC of 28 amps
Branch Circuit size is to be no smaller than 125%
FLC 28 x 1.25 = 35 amps, Table 310.16 tells us #10 AWG is good for 35 amps at 75*C....

Now for Short circuit and ground fault protection....
For an inverse-time breaker: 28AŚ2.5 =70A breaker....

I would stick with the cord and plug for the plasma cutter....#8AWG, and 50 amp receptacle.

As far as the pipe line, I would install a 1" conduit to a jbox for the receptacle, then pipe over to a disconnect for the air compressor...
Are you applying commercial thoughts to residential installs? Now you are going to confuse the amateurs I agree with you 100%.
__________________
All responses based on the 2011 NEC.
If you live in New Jersey click
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. All other states click
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
Please check with local, county and state officials as laws may vary.
Sizing motors
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. Online motor calculator
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. Online calculators
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
electures is offline   Reply With Quote
Old 06-06-2012, 07:20 PM   #10
Newbie
 
Join Date: Jun 2012
Posts: 6
Default

Advice for my new toys!


Got it, Went and purchased most of everything today. Thanks for the help. I figured the same for the wiring, I just wanted someone to double check me. It's been a while since I've done this and things in this field, and they seem to change often. Thanks again.
frodin1 is offline   Reply With Quote
Old 06-06-2012, 09:48 PM   #11
E2 Electrician
 
stickboy1375's Avatar
 
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 4,236
Default

Advice for my new toys!


Quote:
Originally Posted by electures View Post
Are you applying commercial thoughts to residential installs? Now you are going to confuse the amateurs I agree with you 100%.
Not sure what you mean? a motor is a motor regardless where it is installed, The nec dictates everything, so this is the correct answer to the question.
stickboy1375 is offline   Reply With Quote
The Following User Says Thank You to stickboy1375 For This Useful Post:
electures (06-06-2012)
Old 06-06-2012, 09:54 PM   #12
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,513
Default

Advice for my new toys!


Quote:
Originally Posted by stickboy1375 View Post
Not sure what you mean? a motor is a motor regardless where it is installed, The nec dictates everything, so this is the correct answer to the question.
I agree with you. It's just that some of our less knowledgable contributors don't grasp this concept. A motor is a motor. Period.
__________________
All responses based on the 2011 NEC.
If you live in New Jersey click
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. All other states click
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
Please check with local, county and state officials as laws may vary.
Sizing motors
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. Online motor calculator
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. Online calculators
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
electures is offline   Reply With Quote
Old 06-07-2012, 10:46 AM   #13
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,446
Default

Advice for my new toys!


It's worth noting that 70A is the MAXIMUM breaker allowed. It doesn't need to be 70A. Anything 40A or larger should work fine as long as it doesn't trip on startup.
mpoulton is offline   Reply With Quote
Old 06-07-2012, 11:40 AM   #14
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Default

Advice for my new toys!


Quote:
Originally Posted by electures View Post
A motor is a motor. Period.
Except that for the smaller motors the efficiency and PF vary greatly with motor size. With a 1/6 hp fan motor in an HVAC application only half the Volt x Amps that go in come out again as watts.
Yoyizit is offline   Reply With Quote
Old 06-07-2012, 01:21 PM   #15
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,513
Default

Advice for my new toys!


Quote:
Originally Posted by mpoulton View Post
It's worth noting that 70A is the MAXIMUM breaker allowed. It doesn't need to be 70A. Anything 40A or larger should work fine as long as it doesn't trip on startup.
Unless the motor fails to start and run. In that case the IT breaker can be increased, but can't exceed 400% of the FLA. 4 x 28 = 112. SO a 110A breaker can be used.
__________________
All responses based on the 2011 NEC.
If you live in New Jersey click
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. All other states click
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
Please check with local, county and state officials as laws may vary.
Sizing motors
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. Online motor calculator
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
. Online calculators
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.
electures is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Advice is not always correct! Docwhitley Plumbing 9 02-14-2011 09:12 PM
Chain link fence install advice ponch37300 Landscaping & Lawn Care 1 11-10-2010 06:08 PM
Drywall ceiling: Water Damage, looking for advice dawho1 Building & Construction 11 09-13-2010 10:05 AM
looking for Serious advice and Help on Insulation bfan781 Building & Construction 6 05-19-2010 11:02 AM
Electrical Advice Caution!!! Mike Swearingen Electrical 12 03-05-2008 11:51 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.