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EEA Electrician Exam study materials
EEA Electrician Exam study resources

EEA Electrician Exam: Branch Circuits, Feeders, and Service Calculations

EEA Electrician Exam · Work through your exam, one topic at a time.

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Branch Circuits, Feeders, and Service Calculations

The Branch Circuits, Feeders, and Service Calculations domain tests Articles 210, 215, 220, and 230: receptacle spacing, required circuits, GFCI and AFCI protection, load calculations, demand factors, and service sizing. Expect a dwelling or small commercial plan and a request for the minimum service.

Branch circuits

  • 210.52(A): dwelling receptacle outlets must be placed so no point on a wall line is more than 6 ft from an outlet; spacing is generally 12 ft. Kitchen countertops require no point more than 24 in from a receptacle, with at least one per island or peninsula.
  • 210.11(C): at least two 20 A small-appliance circuits, one 20 A laundry circuit, and one 20 A bathroom circuit. Bathroom receptacles require GFCI protection per 210.8.
  • 210.12 requires AFCI protection for dwelling branch circuits in bedrooms, kitchens, laundry areas, and similar spaces. 210.8 requires GFCI protection in bathrooms, kitchens, outdoors, garages, unfinished basements, laundry areas, and within 6 ft of sinks.

Load calculation

  • General lighting per 220.12: 3 VA/ft² for dwellings. Small-appliance and laundry circuits are 1500 VA each per 220.52. Apply Table 220.42 demand: first 3000 VA at 100%, remainder at 35%.
  • Ranges use Table 220.55; four or more appliances may use the 75% demand factor in 220.53; add 25% of the largest motor per 220.50 and 430.24.
  • Service conductors per 230.42 are sized at 100% noncontinuous plus 125% continuous load. A one-family dwelling service is not smaller than 100 A per 230.79.

Worked example

A 2000 ft² dwelling has 6000 VA general lighting, 3000 VA small appliance, 1500 VA laundry, and an 8 kW range. Lighting, small appliance, and laundry total 10,500 VA. Demand = 3000 + 7500 × 35% = 5625 VA. Add the 8000 VA range = 13,625 VA. At 240 V, current = 56.8 A, so the minimum service is 100 A. If a 1.5 hp, 240 V motor were added, add 25% of its Table 430.248 full-load current before dividing.

Traps

  • Applying the 35% demand factor to the first 3000 VA.
  • Using 3 VA/ft² for an office occupancy instead of its table value.
  • Forgetting the range demand table and adding the full nameplate rating.
  • Counting a bathroom circuit as a small-appliance circuit.
  • Omitting the 125% continuous-load factor.