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Old 01-10-2010, 02:18 PM   #16
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Quote:
Originally Posted by Scuba_Dave View Post
Voltage drop is calculated by the distance & the load
So for a 60a panel the Max drop is around 7v
Upgrading to #4 wire makes it only 4.5v drop =3.8%
Usually try to keep it under 5% is my understanding

If your load is going to be 40a or less on the 60a panel then you are OK with #6


http://www.csgnetwork.com/voltagedropcalc.html

Not sure why the calculator says to use 1/2 length of the circuit - when I do I getting differing results... acceptable results for #6 methinks.
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Old 01-10-2010, 02:21 PM   #17
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Total circuit ONE WAY is 125'

Power must go TO the device & back again
--at least what I was told



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Old 01-10-2010, 03:03 PM   #18
 
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Quote:
Originally Posted by Scuba_Dave View Post
Total circuit ONE WAY is 125'

Power must go TO the device & back again
--at least what I was told
Yes it is about 125 feet from the main panel box to the sub panel box on the detached garage.
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Old 01-10-2010, 03:04 PM   #19
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Half the circuit length in this case is 125ft... total circuit length is 250 ft (out and back).
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Old 01-10-2010, 03:06 PM   #20
 
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Originally Posted by vsheetz View Post
Not sure why the calculator says to use 1/2 length of the circuit - when I do I getting differing results... acceptable results for #6 methinks.
On the thing here it says "Select Voltage and Phase" - now (accepting that my panel is 200 amps) - is that 240 volts?

1 phase, 3 phase - What does this mean?

Thanks again for all the knowledge
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Old 01-10-2010, 03:09 PM   #21
 
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Quote:
Originally Posted by HouseHelper View Post
Half the circuit length in this case is 125ft... total circuit length is 250 ft (out and back).
So say I were to use a # 3 awg I would need a min of 300 feet to be on the safe side of cable to run back and forth circuit to circuit correct?

What does awg stand for?

Does places like Lowes and Home D. carry wire this big for exterior applications? or do you need to go to a electrical specific supply company?

Even though this would be ran in the gray pvc pipe underground you still need to get exterior grade wire correct?

Thanks,
Mike
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Old 01-10-2010, 03:16 PM   #22
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THWN is exterior grade wire - allowed to be in buried circuit - HD & Lowes do carry it
AWG is the wire size - American Wire Gauge

#4 wire drops the voltage drop to 4.5v, 1.9% - well within limits



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Old 01-10-2010, 03:20 PM   #23
 
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Quote:
Originally Posted by Scuba_Dave View Post
THWN is exterior grade wire - allowed to be in buried circuit - HD & Lowes do carry it
AWG is the wire size - American Wire Gauge

#4 wire drops the voltage drop to 4.5v, 1.9% - well within limits
Thank you for some more knowledge.

Now maybe you or someone else can confirm with me here and it is something I want to look at price, or at least what is the difference.

if I were to go to a # 3 wire that would be sufficent for a 100 amp sub panel correct?

Last edited by canyonbc; 01-10-2010 at 03:22 PM.
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Old 01-10-2010, 05:41 PM   #24
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Quote:
Originally Posted by canyonbc View Post

if I were to go to a # 3 wire that would be sufficent for a 100 amp sub panel correct?
#3 UF cable buried is only rated for 85A
#2 UF cable buried is rated 95A However you can fuse at 100A
These are copper conductors.
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Old 01-10-2010, 06:15 PM   #25
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If running in conduit then #3 THWN is rated at 100a in 75c rating column
UF uses the 60c rating column

Voltage drop would be 5.9v - 2.9% with a 100a load
If your load was MAX say 60a then the voltage drop would be 3.6v = 1.5%



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Old 01-10-2010, 06:27 PM   #26
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Quote:
Originally Posted by Scuba_Dave View Post
Total circuit ONE WAY is 125'

Power must go TO the device & back again
--at least what I was told
I had thought of that - but still seemed strange to ask the question that way...

I don't see it has a big problem to use #6, unless one would be consistantly or often nearing the 60a current draw.

Last edited by vsheetz; 01-10-2010 at 06:29 PM.
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Old 01-10-2010, 07:27 PM   #27
 
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Quote:
Originally Posted by codeone View Post
#3 UF cable buried is only rated for 85A
#2 UF cable buried is rated 95A However you can fuse at 100A
These are copper conductors.
Well thank you for the information.

Are these put out by the manufacture of is that papa NEC Code.?

Just Wondering and Learning
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Old 01-10-2010, 07:28 PM   #28
 
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Quote:
Originally Posted by Scuba_Dave View Post
If running in conduit then #3 THWN is rated at 100a in 75c rating column
UF uses the 60c rating column

Voltage drop would be 5.9v - 2.9% with a 100a load
If your load was MAX say 60a then the voltage drop would be 3.6v = 1.5%
Not sure what the 75c stands for

But by code and good venture a # 3 THWN can handle a 100 amp ???
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Old 01-10-2010, 07:33 PM   #29
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There are different Temp ratings for wire connections under NEC code
60c (centigrade) column, 75c & 90c

Different type of wire & different types of uses & you look under a different column to see what the wire is rated to carry

I'm not sure who exactly rated the wire (originally) possibly the NEC
But the rated uses are listed in the NEC & controlled by the NEC code
So by the NEC code #3 THWN will handle 100a

Quote:
Originally Posted by vsheetz View Post
I had thought of that - but still seemed strange to ask the question that way...
I thought it weird too...took some getting used to
I have seen some Calc tables where you can choose between total distance & 1/2 distance
It can be confusing, especially if someone does not know the proper value to enter



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Old 01-10-2010, 08:06 PM   #30
 
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Quote:
Originally Posted by Scuba_Dave View Post
There are different Temp ratings for wire connections under NEC code
60c (centigrade) column, 75c & 90c

Different type of wire & different types of uses & you look under a different column to see what the wire is rated to carry

I'm not sure who exactly rated the wire (originally) possibly the NEC
But the rated uses are listed in the NEC & controlled by the NEC code
So by the NEC code #3 THWN will handle 100a



I thought it weird too...took some getting used to
I have seen some Calc tables where you can choose between total distance & 1/2 distance
It can be confusing, especially if someone does not know the proper value to enter
Thank you,

That should settle it, I know the county the garage will be in goes by the NEC Code so I should be good to go.

Thanks everyone again.
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