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Lesson 6: Wiring Diagrams, Symbols, and Cable Identification

Read the lesson, then answer the multiple-choice practice set below. You get instant right or wrong feedback with explanation.

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Japanese Vocabulary Symbols and Diagrams Wiring Methods

Lesson Content

Diagram reading is one of the fastest ways to improve your written exam score because the symbols repeat a lot.

Japanese Key Term

単線図（たんせんず / single-line diagram）

Hiragana

たんせんず

English Meaning

Single-line diagram

Simple Explanation

The diagram language used in the written exam is simplified, but it still follows real wiring logic.

Detailed Explanation

This lesson links symbols to the real wiring methods used in Japanese houses and small buildings. Learn how to identify switch symbols, outlet symbols, junction boxes, grounding marks, cable labels, and how a multi-line diagram expands the single-line view.

Key Vocabulary

- 単線図（たんせんず / single-line diagram）
- 複線図（ふくせんず / multi-line wiring diagram）
- 接地記号（せっちきごう / grounding symbol）
- 回路（かいろ / circuit）

Formula

Symbols do not use a numeric formula, but the rule is: read the symbol first, then trace the conductor path.

Worked Example

If a lamp is connected through a switch, the switch should interrupt the live conductor according to the wiring diagram.

Exam Tips

Pay attention to the symbol shape and the direction of the line. One small symbol can change the answer.

Common Exam Trap

Do not guess from the picture alone. A single-line diagram is a compressed representation, not a photograph.

Site Reality in Japan

In real construction work, electricians must translate between diagrams, actual cables, and inspection requirements.

Practice Question

What does a grounding symbol usually indicate?

Answer

A safety connection to earth

Explanation

The symbol means the equipment is intentionally connected to earth for safety and fault protection.

Lesson Quiz Score0 / 6

1. If Outlet 1 fails open at its load, Outlet 2 is usually:

L ---+---(Outlet 1)
     +---(Outlet 2)
N ---+---(Outlet 1/2)

In a parallel branch arrangement, one load open-circuit does not necessarily interrupt other branches.

2. Primary purpose of the PE line here is:

PE ------------------------(Metal case)
L,N -----------------------(Appliance)

PE is for protective earthing and fault-current safety, not normal operating current.

3. With SW1 open, the expected state is:

L --[SW1]--+--(Lamp A)--N
           +--(Lamp B)--N

SW1 is upstream of both branch lamps, so opening it removes supply to both.

4. If the node above has no dot at crossing in exam notation, you should assume:

L ----(Node)----[SW]----(Lamp)
      
N ------------------------(Lamp)

Standard exam diagram logic treats crossings as non-connections unless explicit junction indication is given.

5. Most likely question theme for this hierarchy is:

DB -> Main breaker -> Branch breaker -> Lighting branch

Hierarchical protective chains are used to test protection role and branch isolation understanding.

6. A resistor is 20 ohms and the supply is 100 V. What current flows?

I = V / R = 100 / 20 = 5 A.

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