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How do 10250T series overlapping contact blocks work?

The ECNO contact closes before the LONC contact opens. The ECNO contact closes before the LONC contact opens. Dimensionally the ECNO (Early Closing Normally Open) block is .026 inch longer than the LONC (Late Opening Normally Closed) block. This ensures the normally open block will close before the normally closed block opens in circuit operation. Overlapping contacts are used when a circuit can not be allowed to open when contacts change state.