NEC Section 110-34(a) and Table 110-34(a) list the minimum clearance required for working spaces in front of high-voltage electrical equipment such as switchboards, control panels, switches, circuit breakers, switchgear, motor controllers, etc.

There are three conditions to apply as in NEC Section 110-16(a) and Table 110-16(a)

1. Where there are exposed live components on one side of a space and no live or ungrounded parts on the other side.

2. Where there are exposed live components on one side and grounded parts on the other such as concrete, brick, and tile walls that are considered to be grounded parts.

3. Where there are exposed live components on both sides.

See Figure 2-4 for the clearance requirements in front of electrical equipment rated at over 600 V.

See NEC Section 110-34(a) Exception for clearance requirements in the rear of electrical equipment.

Figure 2-4. Minimum clearances in front of electrical equipment (over 600 V).

2.10 IDENTIFICATION OF DISCONNECTION MEANS

Switches in service panels, subpanels, or elsewhere shall be marked to show what loads or equipment are supplied.

2.10.1 DISCONNECTING MEANS

All disconnecting means (switches or circuit breakers) shall be located for easy access and shall be clearly and permanently marked to show the purposes of the disconnects, unless located and arranged so that the purpose is evident. Labeling should match and be traceable to appropriate drawings. This is required by 29 CFR 1910.303(b) and NEC Section 110-22 and applies to all existing electrical systems and all new, modernized, expanded, or altered electrical systems. Disconnecting means shall be capable of being locked out where required.

2.10.2 PANELBOARD CIRCUIT DIRECTORIES

Panelboard circuit directories shall be provided and fully and clearly filled out.

2.10.3 ENCLOSURE LABELING

Printed labeling or embossed identification plates affixed to enclosures shall comply with the requirements that disconnects be "legibly marked" and that the "marking shall be of sufficient durability" for the environment involved [NEC Section 110-22 and 29 CFR 1910.303(f)].

2.10.4 LOAD LABELING

As with the disconnecting device, the load should be labeled. For example, the motor, the controller, and the disconnecting device could have the same identification number, etc.

2.10.5 SOURCE LABELING

The source supplying power to the disconnecting means and load should be labeled as well. This requirement allows the electrical worker to know the identification of the elements from the source of power through the entire circuit. (See Figure 2-5.)