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Electrical Code for Wire In Conduit

electrical-wires-in-couduits
Summary: National Electrical Code Appendix C Table C1 - Shows how the Maximum Number of Wires in Conduits including EMT, Electrical metallic Tubing. This information is based upon NEC Table 1, Chapter 9.

Safe Practices for Installing Electrical Wire into Conduit




Maximum Number of Wire Conductors

It is very important to understand the limitations when installing wire into conduit.

Facts About Wires in Conduit:

Wire insulation is rated upon the amount of heat it can safely withstand.

Electricity passing through wires will generate heat.

Wire fill inside conduit must never exceed the specified amount to prevent overheating of the wires inside the conduit.

Number of Wires in Electrical Metallic Tubing


The Maximum Number of Conductors in EMT, Electrical Metallic Tubing.

Type

Conductor

EMT Conduit Trade Size (in.)

THHN,
THWN,
THWN-2

Size
(AWG /
kcmil)

½

¾

1

1¼

1½

2

2½

3

3½

4
14
12
10
8		 12
9
5
3		 22
16
10
6		 35
26
16
9		 61
45
28
16		 84
61
38
22		 138
101
63
36		 241
176
111
64		 364
266
167
96		 476
347
219
126		 608
443
279
161

6
4
3
2
1

2
1
1
1
1

4
2
1
1
1

7
4
3
3
1

12
7
6
5
4

16
10
8
7
5

26
16
13
11
8

46
28
24
20
15

69
43
36
30
22

91
56
47
40
29

116
71
60
51
37

1/0
2/0
3/0
4/0
250

1
0
0
0
0

1
1
1
1
0

1
1
1
1
1

3
2
1
1
1

4
3
3
2
1

7
6
5
4
3

12
10
8
7
6

19
16
13
11
9

25
20
17
14
11

32
26
22
18
15

300
350
400
500
600

0
0
0
0
0

0
0
0
0
0

1
1
0
0
0

1
1
1
1
1

1
1
1
1
1

3
2
1
1
1

5
4
4
3
2

7
6
6
5
4

10
9
8
6
5

13
11
10
8
7
700
750
800
900
1000

0
0
0
0
0

0
0
0
0
0

0
0
0
0
0

1
0
0
0
0

1
1
1
1
1

1
1
1
1
1

2
1
1
1
1

3
3
3
3
2

4
4
4
3
3

6
5
5
4
4


The Basics of Electrical Wires in Conduits


IMPORTANT:
The amount of wire fill inside any electrical conduit does not imply how many wires can be stuffed into the conduit, but rather how many wires of the right type may be safely installed to prevent overheating of the electrical wiring.

A conduit that will be used for an electrical project must be approved for the application.

The type of electrical wire to be installed into the conduit must be approved for the project as well, with special attention given to the type of insulation. For example, some types of insulation may not be used for underground projects.

There are several different types of wire insulation which will have a determination about the application the wire may be used for. The temperature rating is just one factor to consider when selecting a wire type.

The amount of wire fill inside a conduit must be configured properly to prevent overheating of the wire, which is why conduit fill tables are very important.

While using a wire fill table for electrical conduit it is best to size the conduit up to the next incremental size to be sure the conduit is not overfilled, and it will make pulling in the wires much easier.


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Electrical Tip

The Safest Way to Test Electrical Devices and Identify Electric Wiring!

The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester, [amazon.com], I use for the detection of Standard Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.

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