CEA Reading Electrical Blueprints 3

Question 1

On an electrical blueprint, 'EMT' in a conduit note refers to:

Accepted Answer

Electrical Metallic Tubing

Answer

EMT stands for Electrical Metallic Tubing, a thin-wall metal conduit commonly specified on commercial drawings.

Question 2

A blueprint note reads '3-#12 AWG in ¾" EMT.' How many conductors are in this conduit?

Accepted Answer

3

Answer

The '3' prefix indicates three individual conductors—typically two hots and a neutral, or two hots plus a ground.

Question 3

On a single-line diagram, a diagonal line through a conductor symbol indicates:

Accepted Answer

The number of conductors in that run

Answer

Diagonal tick marks across a single line indicate the number of conductors bundled in that run.

Question 4

What does the abbreviation 'MLO' mean in a panel schedule on blueprints?

Accepted Answer

Main Lugs Only

Answer

MLO means Main Lugs Only, indicating a panelboard without a main circuit breaker—fed from an upstream device.

Question 5

Which scale is MOST commonly used for electrical floor plans in commercial construction?

Accepted Answer

1/4" = 1'-0"

Answer

1/4" = 1'-0" is the most common scale for commercial electrical floor plans, providing enough detail while fitting on standard sheets.

(CEA) Certified Electrical Apprentice Practice Test