How Deep Should a Trench Be for an Electrical Line?

How Deep Should a Trench Be for an Electrical Line?

In Ontario, the minimum burial depth for electrical cables depends on the wiring method. Direct-buried cable (Type TECK or USE-2) requires a minimum of 600 mm (24 inches) in most residential applications. Rigid conduit or rigid metallic conduit can be buried at 450 mm (18 inches). Under a concrete slab or pavement, conduit can be as shallow as 100 mm (4 inches). These are Ontario Electrical Safety Code minimums — going deeper is always acceptable and often advisable where frost heave or future excavation is a concern.

Depth by Wiring Method

• Direct-buried cable (TECK or USE-2): 600 mm minimum in residential applications
• Rigid PVC conduit: 450 mm minimum
• Rigid metal conduit or IMC: 150 mm minimum
• Under concrete slab or equivalent: 100 mm minimum in conduit
• Under a roadway: 600 mm minimum regardless of wiring method

Other Requirements

Beyond depth, the trench must have appropriate bedding — direct-buried cable should be surrounded by sand or fine soil free of sharp rocks. Warning tape or tracer wire must be installed above the cable to alert future excavators. The cable route should be documented with measurements from permanent structures. All underground work requires an ESA permit and inspection by a Licensed Electrical Contractor.

EZSMART installs underground electrical lines across Ontario for garages, outbuildings, pools, and landscape lighting. Contact us for a quote on your project.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp