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  #11  
Old 08-01-2006, 09:16 AM
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Quote:
Originally Posted by houlibar
Sure, that would be a good topic.
Did it already, under the shop forum.

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Originally Posted by houlibar
I've got a pigtail made up now. Couldn't find the correct plugs at HD or any hardware store over the weekend.
I get mine from an electrical supply house.

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Originally Posted by houlibar
So Monday I had the LWS get the plugs and 6' of #8.
It is a 50 amp outlet you need #6 wire not #8, this is not an area you wanna go cheap!
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  #12  
Old 08-01-2006, 10:37 AM
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It is a 50 amp outlet you need #6 wire not #8, this is not an area you wanna go cheap!
8 isnt cheap, its really pretty good for 50A welder circuits. Some of them allow for number 12 on 50A, thats cheap,,, haHAHA,,, but it is legal depending on the machine connected to it. A very common setup back in the day was a 10 wire 50A for buzz boxxes. They were installed by the millions.
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  #13  
Old 08-01-2006, 10:42 AM
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Originally Posted by Sberry27
8 isnt cheap, its really pretty good for 50A welder circuits. Some of them allow for number 12 on 50A, thats cheap,,, haHAHA,,, but it is legal depending on the machine connected to it.
Nothing cheap any more. My point is he may be running a plasma cutter or welder off it now but what is he gonna be running off it down the road??? 8 or 10 may not handle it or the duty cycle.

Quote:
Originally Posted by Sberry27
A very common setup back in the day was a 10 wire 50A for buzz boxxes. They were installed by the millions.
on a 20% duty cycle machine that is fine but... Anyway, present company excluded, 9 out 10 farmers cant weld for ****!
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  #14  
Old 08-01-2006, 12:07 PM
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Ron's right. Cords have lower ampacities than the equivilently-sized conductors in a raceway (conduit, MC, or NM). Again, this would be for 100% duty cycle applications.

BUT, would #8 bother me greatly here? Not really.

One of my adapting extensions is made with 12/5 cord with the hots each being a pair of paralleled #12s. Works fine. Don't tell anyone.
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  #15  
Old 08-01-2006, 03:29 PM
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Number 8 is often used on circuits of 100A, depending on the machine.
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  #16  
Old 08-02-2006, 12:49 AM
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Well the manual that came with the welder it does say #6 for a 50A 240V cable with four conductors. But in the section on generating it also says for 9.5 KW load, 40A 240V, #8 cable can be used up to a length of 90'.

My pigtail is only 6'. So I think I'll be okay. I didn't pick out the conductor size or the plugs. The LWS gave me what they generally recommend for that application. But if I need to make up a 4 conductor cable to power the whole house with, I will definately go for the #6 cable.

Just so folks can see what we're talking about, I snapped a photo of the #8 pigtail along side the #10 that came on the plasma machine.
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  #17  
Old 08-02-2006, 01:49 AM
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Originally Posted by houlibar
... But in the section on generating it also says for 9.5 KW load, 40A 240V, #8 cable can be used up to a length of 90'. ...
There's the key right there. Stay with the #8 for everything. It may be a 50A-rated receptacle, but it can only put out approx. 40A non-surge anyway!

#8 cord will be significantly cheaper and easier to roll up and store than #6, which will just be wasted copper in this installation.
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  #18  
Old 08-02-2006, 11:20 AM
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In Shades case it may pay to wire up, the 6 allows for breaker changes with some machines. As a general guideline the supply wire should be one size bigger than the cord on the machine especially with some length to the runs. Most machines for the home crowd do very nicely on a number 8, small stick machines, feeders to 250A and the small tig machines. Any time the breaker is over 100A a 6 must be used, some of the transformer machines allow for 8 wire but use larger breakers.
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  #19  
Old 08-02-2006, 11:57 AM
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Ron's applications can use the same adapter for up to 100% duty cycle applications from 50+ amps of shore power.

Scott's is specifically for his engine-drive, which can't output past the 100% rating of #8 SO cord anyway.
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  #20  
Old 08-03-2006, 03:00 AM
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Quote:
Originally Posted by houlibar
Well the manual that came with the welder it does say #6 for a 50A 240V cable with four conductors.
Your welder has three conductors?

Quote:
My pigtail is only 6'. So I think I'll be okay.

http://www.electrician2.com/articles...alculator.html
Scroll down to the calculator.
Be sure to enter the proper temperature.
----------------------------------------------

The figures should be close enough to get an idea of what a 6ft cord # 8 gauge copper wire will do with a 50 amp Load.
The calculations are accurate on Loads like heaters (resistance Loads)
*Different welders can alter the figures due to circuitry.


For a 6ft extension cord, 8 gauge copper wire.
The resistance of the wire will determine the current loss.

Say 240 volts with a 50 amp LOAD.

The calculator link above comes up with.
0.5 volt, voltage drop with a 50 amp LOAD.
0.5 volts ÷ 50 amps = 0.01 ohms. that's the resistance of the 6' of extension cord.

0.5 volts X 50 amps = 25 watts.
The cord will dissipate 25 watts of power. Lost power due to its resistance with a 50 amp LOAD.

240v ÷ 50 LOAD amps = 4.8 ohms resistance of LOAD.
4.8 ohms + 0.01 ohms of the cord = 4.81 ohms.

240v ÷ 4.81 Total ohms = 49.896 amps.
50 amps - 49.896 amps = 0.104 amps
The 6 ft extension cord has lowered the input 0.104 amps due to its added resistance.


The reduction of 0.104 amps to any 50 amp LOAD is not going to be noticeable.

===================
++++++++++++
My personal choice.
For wiring that is used inside the house, I would always go with the largest size wire, and never install a breaker larger then the current capacity of the wire.
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