» Guide to Home Wiring
» Ask an Electrical Question
Electrical Code for Wire In Conduit
|
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, |
Size |
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 |
2 |
4 |
7 |
12 |
16 |
26 |
46 |
69 |
91 |
116 |
|
1/0 |
1 |
1 |
1 |
3 |
4 |
7 |
12 |
19 |
25 |
32 |
|
300 |
0 |
0 |
1 |
1 |
1 |
3 |
5 |
7 |
10 |
13 |
|
| 700 750 800 900 1000 |
0 |
0 |
0 |
1 |
1 |
1 |
2 |
3 |
4 |
6 |
|
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.
|
|
||||||||||
Top of Page |
