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Home of America's Electrical Code Doctor
Chuck Cossin
Below is a great NEC voltage drop calculator and
standard sizes for panels, fuses and other devices.

Voltage Drop &
Conductor Sizing

Calculate Suggested Minimum Conductor Size
Assume a 3% max. conductor voltage drop
Some circuit configurations suggest a max voltage drop of 5% - see the NEC for details
Select Voltage Select Wire Type & Phase
120 Volts Copper
208 Volts Aluminum
240 Volts  
277 Volts Single Phase
480 Volts Three Phase
 
  Enter Length of Wire (One Way) in Ft
  Enter Circuit Amperage
  Suggested Min. Wire Size (Calculated)

THIS USE IS INTENDED ONLY FOR QUALIFIED ELECTRICIANS.
Not Intended As A Design Specification.  OTHER FACTORS APPLY.
As ALWAYS - Consult the full NEC & local authorities for specifics.

3 Phase Un-balanced
Current Calculator

Enter: Ø A  Current:

Enter: Ø B  Current:

Enter: Ø C  Current:



Un-balanced Current:

`PANEL BOARD SIZES
Single Phase - 3 Wire Systems
40A | 100A | 150A | 225A | 400A
70A | 125A | 200A | 300A | 600 A
Three Phase - 4 Wire Systems
60A | 150A | 225A | 400A
125A | 200A | 300A | 600A
SWITCH BOARD
AND SWITCH GEAR SIZES
Single Phase Three Phase
200 A
400 A
600 A
800 A
1200 A
1600 A
2000 A
2500 A
3000 A
4000 A		 400 A
600 A
800 A
1200 A
1600 A
2000 A
2500 A
3000 A
4000 A
STANDARD OCPD SIZES
CIRCUIT BREAKERS AND FUSES
15 A
20 A
25 A
30 A
35 A
40 A
45 A
50 A
60 A		 70 A
80 A
90 A
100 A
110 A
125 A
150 A
175 A
200 A		 225 A
250 A
300 A
350 A
400 A
450 A
500 A
600 A
700 A		 800 A
1000 A
1200 A
1600 A
2000 A
2500 A
3000 A
4000 A
5000 A
6000 A
Other standard FUSE sizes are
1A, 3A, 6A, and 10A.
GUTTER AND WIREWAY SIZES
2½" x 2½"
4" x 4"		 6" x 6"
8" x 8"		 10" x 10"
Available in 12", 24",
36", 48", and 60" lengths.
STANDARD DISCONNECT SIZES
30A
60A
100a		 200A
400A
600A		 800A
1200A
1400A		 1600A
1800A
PULL AND JUNCTION BOX SIZES
4" x 4" x 4"
6" x 4" x 4"
6" x 6" x 4"
6" x 6" x 6"
8" x 6" x 4"
8" x 6" x 6"
8" x 6" x 8"
8" x 8" x 4"
8" x 8" x 6"
8" x 8" x 8"		 10" x 8" x 4"
10" x 8" x 6"
10" x 10" x 4"
10" x 10" x 6"
10" x 10" x 8"
12" x 8" x 4"
12" x 8" x 6"
12" x 10" x 4"
12" x 10" x 6"
12" x 12" x 4"		 12" x 12" x 6"
12" x 12" x 8"
15" x 12" x 4"
15" x 12" x 6"
18" x 12" x 4"
18" x 12" x 6"
18" x 18" x 4"
18" x 18" x 6"
24" x 18" x 6"
24" x 24" x 6"
24" x 24" x 8"
BUSWAY AND BUSDUCT AMPACITIES
Single Phase and Three Phase
225 A
400 A
600 A
800 A
1000 A
1200 A
1350 A 		1600 A
2000 A
2500 A
3000 A
4000 A
5000 A

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