Tolerance ZonesDig Safely Home< BackNext >


The tolerance zone protects buried utilities.
Respect the “tolerance zone.” In Pennsylvania, this is a safety area that spans the width of a marked utility, plus 18 inches from each indicated outside edge. If your excavation encroaches within this zone, contact Duquesne Light Company, and we’ll send a representative out to your job site.

Do not use power-digging equipment within this zone. The zone provides a margin of error in case the locator marks are slightly off. It also provides a buffer zone to prevent damage resulting from nearby excavation.

The tolerance zone also protects you.
If you do not respect the tolerance zone, you risk contacting buried utilities. You also risk damaging them indirectly by removing supporting soil, which could cause the utility to bend or break. You could be injured or killed, and your company could be liable for any damages that occur.


To avoid damaging buried utilities, do not power dig within the tolerance zone. Hand dig or use vacuum technology instead.