Clearance Requirements for ComPact NSXm Circuit Breakers

Introduction

When installing ComPact NSXm circuit breakers in equipment, minimum distances (safety clearance) must be maintained between the device and panels, bars, or any metal installed nearby.

Minimum distances depend on the ultimate breaking capacity, and are defined by tests carried out in accordance with the IEC/EN 60947-2 standard.

If IEC/EN installation conformity is not checked by type tests, you must also:

Use insulated bars for circuit breaker connections.
Block off the busbars by using rear insulation screens.

Equipment Installation Requirements

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E, CSA Z462, NOM-029-STPS, or local equivalent. This equipment must only be installed and serviced by qualified electrical personnel. Turn off all power supplying this equipment before working on or inside equipment. Always use a properly rated voltage sensing device to confirm that power is off. Replace all devices, doors, and covers before turning on power to this equipment. Beware of potential hazards, and carefully inspect the work area for tools and objects that may have been left inside the equipment. Failure to follow these instructions will result in death or serious injury.

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E, CSA Z462, NOM-029-STPS, or local equivalent.
This equipment must only be installed and serviced by qualified electrical personnel.
Turn off all power supplying this equipment before working on or inside equipment.
Always use a properly rated voltage sensing device to confirm that power is off.
Replace all devices, doors, and covers before turning on power to this equipment.
Beware of potential hazards, and carefully inspect the work area for tools and objects that may have been left inside the equipment.

Failure to follow these instructions will result in death or serious injury.

Follow these guidelines when installing circuit breakers in equipment:

Respect minimum distances.
Perform dielectric strength tests, thermal calculations, and temperature rise tests as required by the configuration of the installation.
Respect the limits defined in the derating tables, depending on the ambient temperature (ratings are based on IEC/EN 60947-2 standard).

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH Install circuit breaker so minimum clearance distance to grounded metal is maintained. Failure to follow these instructions will result in death or serious injury.

Minimum Distances for Side-by-Side Installation

There is no minimum distance required between circuit breakers installed side-by-side.

Minimum Clearance Without Insulation Accessories

The minimum clearance distances required around circuit breakers without insulation accessories are shown below.

3P/4P	Clearance (Operating voltage ≤690 V)
	With painted sheet metal: A1: 30 mm (1.18 in.) A2: 5 mm (0.19 in.) B: 0 mm (0 in.) With bare sheet metal: A1: 40 mm (1.57 in.) A2: 5 mm (0.19 in.) B: 5 mm (0.19 in.)

3P/4P

Clearance (Operating voltage ≤690 V)

With painted sheet metal:

A1: 30 mm (1.18 in.)
A2: 5 mm (0.19 in.)
B: 0 mm (0 in.)

With bare sheet metal:

A1: 40 mm (1.57 in.)
A2: 5 mm (0.19 in.)
B: 5 mm (0.19 in.)

Minimum Clearance with Interphase Barriers

The minimum clearance distances required around circuit breakers equipped with interphase barriers are shown below.

3P/4P	Clearance (Operating voltage ≤690 V)
	With painted sheet metal: A1: 0 mm (0 in.) A2: 0 mm (0 in.) B: 0 mm (0 in.) With bare sheet metal: A1: 0 mm (0 in.) A2: 0 mm (0 in.) B: 5 mm (0.19 in.)

3P/4P

Clearance (Operating voltage ≤690 V)

With painted sheet metal:

A1: 0 mm (0 in.)
A2: 0 mm (0 in.)
B: 0 mm (0 in.)

With bare sheet metal:

A1: 0 mm (0 in.)
A2: 0 mm (0 in.)
B: 5 mm (0.19 in.)

Minimum Clearance with Long Terminal Shields

The minimum clearance distances required around circuit breakers equipped with long terminal shields are shown below.

3P/4P	Clearance (Operating voltage ≤690 V)
	With painted sheet metal: A1: 0 mm (0 in.) A2: 0 mm (0 in.) B: 0 mm (0 in.) With bare sheet metal: A1: 0 mm (0 in.) A2: 0 mm (0 in.) B: 5 mm (0.19 in.)

3P/4P

Clearance (Operating voltage ≤690 V)

With painted sheet metal:

A1: 0 mm (0 in.)
A2: 0 mm (0 in.)
B: 0 mm (0 in.)

With bare sheet metal:

A1: 0 mm (0 in.)
A2: 0 mm (0 in.)
B: 5 mm (0.19 in.)

Minimum Clearance to Bare Busbars

The minimum clearance distances required around circuit breakers that use busbars are shown below.

3P/4P	Spacing	Clearance⁽¹⁾ (Operating voltage ≤690 V)
	E ≤ 60 mm (2.36 in.)	D1: 200 mm (7.87 in.) D2: 100 mm (3.94 in.)
	E > 60 mm (2.36 in.)	D1: 120 mm (4.72 in.) D2: 60 mm (2.36 in.)
(1) These clearances can be reduced for special installations if they are validated with appropriate tests.

Minimum Clearance Between Backplate and Uninsulated Power Connections

For all types of ComPact NSXm circuit breakers that use uninsulated power connections (for example, busbars, spreaders, or uninsulated crimped lugs), the minimum clearance distance with the enclosure backplate is shown below.

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A rear insulation screen or long terminal shield is required if the distance C is less than 8 mm (0.32 in).