txturbo
Well-known member
Ok electricians.....I have a 200 amp panel on my meter pole. I need to run 100 amps to my shop panel that is 160 feet away through 2" conduit. What size wire do I need?
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Wire sizing
- Thread starter txturbo
- Start date
mjbasford
Active member
#3/0-CU for a ~2.5% Voltage drop
#1-CU for a ~4.2% Voltage drop
Not sure if you are getting the 3/0 through 2" or not tho.
#1-CU for a ~4.2% Voltage drop
Not sure if you are getting the 3/0 through 2" or not tho.
wyliesdiesels
Well-known member
#3/0-CU for a ~2.5% Voltage drop
#1-CU for a ~4.2% Voltage drop
Not sure if you are getting the 3/0 through 2" or not tho.
Woa nelly! Where'd u get those numbers?
I do the math by hand and got way smaller:
#2 CU will give u a 6.22v or 2.6% drop @ 100a full load.
If the OP wants to use al go with #1/0 al which would give u a 6.43v drop or 2.7%.
So OP u would need 2-2-2-8 CU (the #8 is for the EGC) or 1/0-1/0-1/0-6 AL
OP dont forget 2 rods and a ground bar kit. Also make sure neutral bar is isolated in the subpanel.
pattenp
Well-known member
Use 2/0-2/0-2/0-1 MHF (Mobile Home Feeder). It's an assembled cable ready to go. Can be direct bury or put in conduit. Best practice is to put in conduit underground, has to be in conduit where above ground. 2" conduit will work.
mjbasford
Active member
Woa nelly! Where'd u get those numbers?
I do the math by hand and got way smaller:
#2 CU will give u a 6.22v or 2.6% drop @ 100a full load.
If the OP wants to use al go with #1/0 al which would give u a 6.43v drop or 2.7%.
So OP u would need 2-2-2-8 CU (the #8 is for the EGC) or 1/0-1/0-1/0-6 AL
OP dont forget 2 rods and a ground bar kit. Also make sure neutral bar is isolated in the subpanel.
used the southwire online calculator.
http://www.southwire.com/support/voltage-drop-calculator.htm
I did add 10' to his distance tho, to compensate for mis-measuring.
edit: funny, i went back and did again, and i got the same results as you.
Disregard my previous post OP, i am stupid currently.
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wyliesdiesels
Well-known member
The southwire calculator typically uses the 60* c ampacity column. If u do the math yourself u will get better results.
i like this option....thanks.....I didn't even think about MHF.Use 2/0-2/0-2/0-1 MHF (Mobile Home Feeder). It's an assembled cable ready to go. Can be direct bury or put in conduit. Best practice is to put in conduit underground, has to be in conduit where above ground. 2" conduit will work.
sberry
Banned
I dont really use those calcs either. My first thought was it got plugged in for 120v.
I have a chart from an electric supply that is super simple, not sure I even know the math to really do it any way, ha, but really do it from memory and simple estimation.
I have a chart from an electric supply that is super simple, not sure I even know the math to really do it any way, ha, but really do it from memory and simple estimation.
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sberry
Banned
I would have real trouble with the math to pass a masters, the other issue is I really don't know anything about electricity. Both a real drawback,, ha
wyliesdiesels
Well-known member
I dont really use those calcs either. My first thought was it got plugged in for 120v.
I have a chart from an electric supply that is super simple, not sure I even know the math to really do it any way, ha, but really do it from memory and simple estimation.
The math is easy!
K * 2 * L * C / VD
K=resistance of wire 12.9 for CU 21.2 for AL
L= one way length of wire
C= current or amps
VD= voltage drop. For 240v it would be 7.2, 240 * .03 for 3% = 7.2v
U can replace VD with a specified wire cir mils size to figure out how much voltage drop a given wire size will have. U will need a awg/cir mils chart to do so:
http://www.engineeringtoolbox.com/awg-wire-gauge-circular-mils-d_819.html
So then it would be
K * 2 * L * C / cir mils size
sberry
Banned
It is but I have done this long enough I don't need to do a calc every time I install a wire. I was talking to a guy a while back, claims to do this work all the time and got to look up and calc a ground wire for 200 a servive.
wyliesdiesels
Well-known member
Wow....nobody around here has 2/0-2/0-2/0-1 MHF.
Special order?
pattenp
Well-known member
How about 2/0-2/0-1-4? Here it is online..... http://www.wireandcabletogo.com/Alu...-0-1-4-Aluminum-Mobile-Home-Feeder-Cable.html
pattenp
Well-known member
Is there anything in the code that says I can't use un-insulated solid copper ground wire for the EGC going to my sub panel?
You can do that. What are you planning to use for the other 3 wires? Nobody around you even carries single conductor aluminum THWN or XHHW or RHH/RHW?
Aceman
Well-known member
I already have the other wire. I was just asking about the EGC because I have a whole spool of it already.
What size and type of wire are you using for the "hots" and "neutral"? What size wire is this bare solid copper you're wanting to use?
Aceman
Well-known member
2-2-2 THHN/THWN and the bare copper is #8.
310.106(C) in the 2014 NEC doesn't allow #8 and larger solid wire in conduit unless specifically permitted elsewhere in the code.
It's somewhat of a gray area whether a ground wire meets the requirements.