How to Seal Conduit Entering the Breaker Box

How to Seal Conduit Entering the Breaker Box

Conduit that enters a panel or sub-panel from outside or from an unheated space must be sealed to prevent moisture and pests from entering the enclosure. An unsealed conduit acts like a chimney, drawing cold air, insects, and humidity into the panel. This can cause condensation on live components, corrosion of bus bars and terminals, and in cold climates, freezing of moisture inside the panel.

Sealing Methods

• Use a pull box or conduit seal (Dux Seal or equivalent) packed into the conduit at the point of entry — this is required by the Canadian Electrical Code where conduit passes from an unheated space into a heated one
• For PVC conduit entering through the exterior wall into an indoor panel, install a conduit seal fitting and pack with the correct sealing compound
• For liquid-tight flexible conduit (used for the last section of an outdoor conduit run), the liquid-tight fittings create a mechanical seal at the box entry
• After sealing, inspect the conduit exterior where it exits the building and apply caulk or conduit weatherhead to prevent water entry at that point as well

Permit and Inspection

Work inside or on a service panel requires an ESA permit. Sealing conduit entries is typically part of a larger panel or outdoor circuit installation, both of which are permitted work. A Licensed Electrical Contractor ensures all conduit entries are sealed at inspection. EZSMART handles panel installations, outdoor circuit work, and conduit sealing across Ontario.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp