How to Differentiate Between NEMA 5-20 and NEMA 6-20 Plugs

If you have trouble telling a NEMA 5-20 plug from a NEMA 6-20 plug, you’re not alone. The two configurations look very similar, and their connector ends can appear reversed, which often causes confusion.

The easiest way to identify them is to look at the plug with the ground pin positioned at the top.

How to Identify a NEMA 5-20

With a NEMA 5-20P plug and the ground pin at the top:

• The vertical blade is on the right
• The horizontal blade is on the left
• It is a 125V configuration

On the NEMA 5-20 receptacle or connector end, the blade positions appear reversed. This is because the plug essentially flips orientation when inserted into the connector.

How to Identify a NEMA 6-20

With a NEMA 6-20P plug and the ground pin at the top:

• The horizontal blade is on the right
• The vertical blade is on the left
• It is a 250V configuration

Just like the NEMA 5-20, the connector end can look like the opposite orientation. This can make the two configurations appear as though they should fit together.

Can a NEMA 6-20 Plug Into a NEMA 5-20 Outlet?

No. NEMA 5-20 and NEMA 6-20 are different configurations and are not designed to mate with each other.

When looking at the plugs side-by-side, some of the blades may appear to line up. However, once the plug is rotated into the position required for insertion, the horizontal and vertical blades do not match.

This is an important distinction because NEMA 5-20 is typically used for 125V applications, while NEMA 6-20 is used for 250V applications.

NEMA 5-20 vs. NEMA 6-20: Quick Reference

Tip: When you're unsure which NEMA configuration you have, use a NEMA configuration chart or wiring diagram. AC WORKS® also provides NEMA configuration information and technical resources to help identify plugs and receptacles.

Frequently Asked Questions

How do I tell the difference between a NEMA 5-20 and 6-20?
Look at the plug with the ground pin on top. A NEMA 5-20 has the vertical blade on the right and horizontal blade on the left. A NEMA 6-20 has the horizontal blade on the right and vertical blade on the left.

Is NEMA 5-20 125V or 250V?
NEMA 5-20 is a 125V configuration.

Is NEMA 6-20 125V or 250V?
NEMA 6-20 is a 250V configuration.

Can a NEMA 5-20 plug into a NEMA 6-20 receptacle?
No. The blade configurations are different and are designed to prevent the two configurations from being connected incorrectly.

Why do NEMA 5-20 and NEMA 6-20 connectors look reversed?
The plug and connector are oriented opposite each other when viewed separately. Once the plug is rotated into position for insertion, the blade arrangement becomes clear.