Dsiconnecting Means

DOE-HDBK-1092-98

b. Remote controls that may introduce hazardous conditions into the cell line working zone

shall employ one or more of the following:

(1) Isolated and ungrounded control circuit in compliance with NEC Section 668-21(a)

(2) Nonconductive rope operator

(3) Pendant pushbutton with either non-conductive support and surfaces or ungrounded

exposed surfaces.

(4) Radio

6.2.2 DISCONNECTING MEANS

The disconnecting means provided for cranes and hoists may consist of two or more lock-open-type

motor circuit switches or circuit breakers. Article 610, Part D, of the NEC, "Disconnecting Means,"

and the installation and operating plans should be studied carefully to determine the disconnecting

means requirements and locations. The two basic disconnects to consider are:

1. The runway conductor (conductors run along a crane runway for power or control) disconnect

which shall:

a. Be readily accessible or operable from the ground or floor level per NEC Section 610-

31(1)

b. Be lockable in the open position per NEC Section 610-31(2)

c. Open all ungrounded conductors simultaneously per NEC Section 610-31(3)

d. Be placed in view of the crane or hoist and the runway conductors per NEC Section 610-

31(4).

2. The crane and hoist disconnect which shall be provided in the leads from the runway contact

conductors or other power supply unless all the following requirements are met:

a. The unit is ground or floor level controlled per NEC Section 610-32, Exception

b. The unit is within view of the power supply disconnecting means per NEC Section 610-

32, Exception

c. No fixed work platform has been provided for servicing the unit per NEC Section 610-

32, Exception.

See Figure 6-1 (a) and (b) for a detailed illustration of the rules pertaining to the disconnecting means

for electric cranes and hoists.

6-4