In Control Engineering's June 1999 issue, p. 77, under "Product Focus: Trends in Terminal Blocks," it states that Wago Corp. "...let its patent for the screwless terminal block expire."

I would like to point out that, with renewals, patents can only last for a maximum of 20 years. Wago didn't let the patent expire. By the manner in which this was stated, Wago was made to look either negligent or stupid. We would like to point out that we have no control over the process!

Until recently, no one has been able to copy our "Cage-Clamp" design, due to the patent cover. Since the expiration, at least seven companies have now copied our technology. Most new I/O products introduced in the last year are "spring clamp" products, many are not even offered with a "screw" alternative, demonstrating the acceptance of this technology.

After more than 100 years of screw terminations, Wago's "Cage-Clamp" has changed the face of wiring techniques for an entire industry.

Michael A. Lane P.E., President, Wago Corp., Germantown, Wis.