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Specifying the Right Cord Set

Video Transcript

Ralph Bright—
Hello, I’m Ralph Bright, Vice President of Marketing and IT at Interpower.

We have real people answering the phones each day at Interpower which means we receive a number of product design questions. Usually if a question has been asked by one person, it means that others also have the same question.

One commonly asked question is: “Why can’t I use a two-wire cable with a three-wire connector or vice versa?”

To answer this question, we have Jon Zobel, Molding Supervisor. Welcome, Jon.

Jon Zobel—
Thank you, Ralph.

Why is it important to design an electrical product using the correct cord?

If equipment is supplied with a Class I plug, meaning a plug with a ground connection, then for safety and emission reasons, it must be connected to an outlet with a ground connection. You need to design your product with the correct cord to prevent shock hazards.

Can you give some examples?

Usually we hear of two scenarios. The first relates to customers designing Class II equipment—that is equipment with no earth ground connection—with the wrong cord. They ask us to make a cord using a Class I plug, cable with three conductors, and a Class II connector. This configuration does not connect the earth ground wire in the connector.

The second example is when customers design Class I equipment—that is equipment with an earth ground connection—with the wrong cord. They ask us to make a two conductor cord with a three terminal connector. This application demands a three-wire cord with a true earth ground connection via a three conductor connector and plug. Without the ground connection, you create a potential shock hazard.

So, the key point in all of this is safety—is that correct?

Yes. Equipment manufacturers should use cords that are safe and that comply with the relevant product safety standards. The safety of cord sets and power cords is demonstrated by having them tested and certified to the applicable standards, such as U-L 817, I-E-C 60799, and C-S-A 22.2 number 21.

Thank you Jon for the information and thank you for joining us today.

If you have a question that you would like answered, please let us know by e-mailing us at or calling us at 1–800–662–2290. For more information, check our website at