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Bolt hole spacing on 50s-70s US vintage switchgear

Thread starter mb3928
Start date Feb 15, 2024

Status: Not open for further replies.

Feb 15, 2024

mb3928

Electrical

Looking to the old-timers here, we often have to replace lugs in switchgear in the Northeast US from the 50s, 60s, and 70s, and we consistently find lugs with boltholes spaced at 1-1/4". Today the NEMA standard spacings are 1-3/8" and 1-3/4".

Does anyone know why this change happened? Was there a change to NEMA standards that resulted in the spacing changing?