The diameter of an electrical conduit varies depending on its size and type. Electrical conduits are manufactured in a range of standard nominal sizes, each having a corresponding outside and inside diameter. The provided reference specifically details the outside diameter for common sizes of Electrical Metallic Tubing (EMT), also known as thinwall conduit.
Understanding Conduit Diameter
It's important to note that the size of electrical conduit is typically referred to by its nominal size, which is a trade size identifier and not the actual physical diameter. The actual physical dimensions, such as the outside diameter (OD) and inside diameter (ID), differ from the nominal size.
The reference provides the following outside diameters for specific nominal sizes of EMT:
Electrical Metallic Tubing (EMT) Data
Based on the information from Taylor Walraven's Electrical Metallic Tubing Data, here are the outside diameters for several common EMT sizes:
| Nominal Conduit Size Inches | Nominal Conduit Size mm | Conduit Outside Diameter Inches |
|---|---|---|
| 1/2" | 16 | 0.706 |
| 3/4" | 21 | 0.992 |
| 1" | 27 | 1.163 |
| 1-1/4" | 35 | 1.510 |
This table shows that a 1/2" nominal conduit size has an outside diameter of 0.706 inches, while a 1-1/4" nominal size has an outside diameter of 1.510 inches.
Why are there different sizes?
Electrical conduits are available in numerous sizes to accommodate varying numbers and sizes of electrical wires (conductors). Proper sizing is crucial for:
- Cable Fill: Ensuring the total cross-sectional area of the wires does not exceed the permitted fill capacity of the conduit, as specified by electrical codes (like the National Electrical Code in the US or the Canadian Electrical Code in Canada).
- Protection: Providing adequate physical protection for the conductors.
- Installation: Allowing for easy pulling of wires through the conduit without damage.
The "diameter" you might be concerned with could be the outside diameter for fitting purposes or the inside diameter (which can be calculated by subtracting twice the wall thickness from the outside diameter) for calculating conduit fill capacity. The reference provides the outside diameter, which is a key dimension for selecting compatible fittings, connectors, and support hardware.
