Short-Circuit Current Rated Power Distribution

Blocks

Cooper Bussmann offers three distinctly different styles of

short-circuit current rated power distribution blocks (PDBs)

and terminal blocks (TBs) to match different application

needs. The differences are whether the power

distribution blocks are enclosed or not, and whether they are

UL1953 Listed PDBs or UL1059 Recognized TBs, which have

different minimum spacing requirements. The table on this

page can assist in the selection of the right series for your

application requirements.

Why these are important?

Assembly short-circuit current ratings (SCCRs) are now

Control Panels. Marking the SCCR on Industrial Control

440.4(B)) is now required by the National Electrical Code.

PDBs or TBs not marked with a SCCR are typically one of

the weakest links and may limit an assembly to no more than

10kA SCCR. The PDBFS and PDB Series have increased

spacing required where used in feeder circuits in equipment

listed to UL508A (UL1059 TBs must be evaluated for proper

spacings). Also, for building wiring systems, the PDBFS

Series and PDB Series power distribution blocks can be used

376.56(B) for PDBs in wireways.

More application info rmation on pages 19-23.

Industrial

Industrial

Control

Control

HVAC

Wireways

Product

Catalog

High

Spacing**

Panels

Panels

UL

Page

UL

Enclosed SCCR*

1” Air

UL 508A

UL 508A

1995

376.56(B)

2” Surface

Branch

Feeder

(Requires

Circuit

Circuit

UL 1953)

Series PDBFS

3

UL 1953 Listed

Yes

Yes

Yes

Yes

Yes

Yes

Power Distribution Blocks

Yes

Series PDB

9

UL 1953 Listed

No***

Yes

Yes

Yes

Yes

Yes

w/optional

Power Distribution Blocks

cover

Series

UL 1059 Recognized

16XXX

13

Terminal Blocks

No***

Yes

No****

Yes

No****

Yes

No

NDN63-WH-UL,

NDN111-WH-UL,

UL 1059 Recognized

14002-3-UL,

16

Terminal Blocks

No

Yes

No

Yes

No

Yes

No

TB300-03SP-UL

Selection Table

† IP-20 finger-safe under specific conditions, see datasheet page 8.

*When protected by proper fuse class with maximum ampere rating specified or smaller.

** See PDB Spacing Requirements for Equipment table below.

***Optional covers are available. Not IP-20, but provide a safety benefit.

****No, except: Yes, if single pole units installed with proper spacings.

Spacing between

Spacing between

live parts of

live parts and

UL Standard

opposite polarity

grounded parts

or enclosure

@600V

508A Feeder

Circuits

508A Branch

Circuits

1995 HVAC

Through air

Over surface

@600V

@600V

1˝

2˝

1˝

Note: Refer to Specific UL standards for complete spacing details.

PDB & TB Minimum Spacing

Requirements for Equipment

Series PDBFS

Series PDB

Series 162 and 163

Magnum Terminal Blocks

Selection Table for SCCR Power Distribution Blocks and

Terminal Blocks

1011

SB-BU09622

Page 2 of 23

Data Sheet 1049