Working Space and Table Navigation

Page review information

Edition covered: NEC (NFPA 70) — article scope per the module — taught against the NEC 2023 corpus basis; the locally enforceable edition governs — verify with the AHJ
Content status: Reviewed
Coverage: Training module: Working Space and Table Navigation — worked as education, not a code determination; the AHJ and enforceable edition govern.
Last reviewed: August 2026
Primary reference: The official published standard — required for final decisions

Confirm the governing edition, jurisdiction, and project-specific requirements before applying anything on this page.

Beginner Time: 15 min Type: Code Application Focus: Panel Design / NEC

After this module: Apply Table 110.26 correctly — read depth, width, and height requirements by condition of maintenance and voltage level.

Prerequisites: NEC Code Reading Fundamentals

Purpose

This module uses working-space review as a training example for how to read NEC tables and condition statements carefully.

Why this example matters

Working-space questions are useful training examples because they force the reader to:

Identify the correct section
Confirm the correct table
Interpret voltage category and condition statements

NEC 110.26 defines working space for equipment operating at 1000 V nominal or less to ground. The table requires knowing the voltage to ground and the condition of the space on the opposite side.

Table-reading discipline

Use this order every time you open an NEC table:

Verify the table title
Identify the row logic
Identify the column logic
Read notes and condition descriptions
Confirm the answer against the actual equipment condition

Do not jump straight to the number

A common mistake is to see a familiar table and grab a value before checking:

Whether the table uses voltage to ground or line-to-line
Which condition applies (Condition 1, 2, or 3 in Table 110.26(A)(1))
Whether nearby notes change the result

Conditions 1, 2, and 3 in Table 110.26(A)(1) describe what is on the opposite side of the working space:

Condition	Description
1	Exposed live parts on one side and no live or grounded parts on the other
2	Exposed live parts on one side and grounded parts on the other
3	Exposed live parts on both sides

Getting the condition wrong changes the required depth from roughly 900 mm (3 ft) to 1.2 m (4 ft) or more.

Practical use outside an exam

The same discipline applies when reading any NEC table in real design work:

Conductor ampacity tables (310.16) — require temperature column and insulation type
Ambient correction tables — require confirming the base temperature assumption
Spacing tables — require confirming voltage class and insulation method
Grounding conductor sizing tables (250.122) — require using the overcurrent device rating as the row key

Working takeaway

Tables are not shortcuts around reading.

They are compact rule structures that still require:

The right section
The right conditions
The right interpretation basis

Getting those three things right before reading the number is the discipline that prevents field rejections.

NEC 2023, Article 110 — Requirements for Electrical Installations
NEC 2023, Article 310 — Conductors for General Wiring
NEC 2023, Article 250 — Grounding and Bonding

← NEC Code Reading Fundamentals ↑ NEC for Machines and Panels Motor and Panel Code Application →

Trust Boundary — Engineering Judgment Required

This site is an independent educational reference for industrial automation standards. It paraphrases and organizes guidance in original language; it is not a substitute for the official published standards, professional engineering judgment, or legal review, and content has not been independently verified against current published editions.

Items marked Review pending await technical review against the identified edition. Items marked Planned have no reviewed source material behind them. Do not rely on this site for compliance determinations, safety-critical design decisions, or legal interpretation.