Quick Hits

QUICK HIT 03

One Building Can't Feed Another — And What Counts as "Outside"

2026 NEC References: 230.5, 230.6, 230.7, 230.8, 230.9, 230.10

🎯 What You'll Learn

Service conductors have specific rules when they travel between buildings and when they're considered outside a building.

🚫 DON'T RUN THEM THROUGH ANOTHER BUILDING

Service conductors supplying one building cannot pass through the interior of another building.

They can run along the exterior of one building to supply another, but the building being supplied needs its own disconnect.

📏 WHEN ARE CONDUCTORS CONSIDERED "OUTSIDE"?

Examples include conductors:

• Under at least 2 inches of concrete

• Encased in at least 2 inches of concrete or brick

• In a qualifying vault

• Under at least 18 inches of earth

• Through an eave using RMC or IMC under the applicable conditions

⚠️ OTHER RULES TO REMEMBER

Service conductors generally can't share a raceway, cable, or handhole with other non-service circuit conductors.

There are specific exceptions, including grounding electrode conductors and certain load-management control conductors.

Service raceways entering a building must be sealed.

Open service conductors and jacketless cable also have clearance requirements from operable windows, doors, and similar openings.

And remember:

Trees aren't service-conductor support structures.

🧠 EXAM-STYLE QUESTION

How much earth cover makes buried service conductors count as "outside the building" when installed in conduit beneath the building?

Answer: 18 inches (450 mm) or more.

📌 QUICK TAKEAWAY

Know the difference between inside, outside, and entering the building.

➡️ Next Quick Hit: Overhead service conductors.

← View Chapter 2 Home

← Back To Article 210 Home

← Back To Quick Hits Home