Building Entrance 5-Pin Modules

3B1E-BAL & 4BIE-PTC/BAL Series

Balanced Operation - Heavy Duty with self-Resetting Current Limiters



The 3B1E-BAL and 4B1E-PTC/BAL premium series of 5 pin, 3 element protector modules are designed to provide superior transient and power fault protection for most standard telephone line applications. The common chamber, 3 electrode gas tube provides true balanced operation. An over voltage on either side of the circuit enables the entire tube to ionize which provides a simultaneous path to ground for both sides of the circuit. This grounding prevents a second arriving transient on the opposite side to pass through to the equipment. Nominal breakdown voltage for the 3B1E/4B1E series is 350VDC.

The PTC (positive temperature compensated) versions include fast acting, self resetting current limiters. These are especially useful where extra protection against "sneak current" type faults is desirable.


The 3B1E-BAL and 4B1E-PTC/BAL premium series are well suited to applications with building entrance terminals as well as central office protectors. The PTC option is recommended for protection against overcurrent situations where the fault voltage is lower than the breakover voltage of the three element gas tube device.

Features Benefits

bulletHeavy duty surge handling capability Superior common chamber design
bulletRugged, dependable operation
bulletReduced service calls than 2 element designs
bulletBalanced operation
bulletPrevents damage by "lagging" or sneak transients
bulletUL listed Documented safe performance






  DC Breakdown (nominal)






1Vrms@1KHZ, 50VDC



  Impulse Breakdown Voltage


  Insulation Resistance


 @ 100V/Ásec



>100M ohms




Fail- safe Operation


  DC Holdover Voltage


@1.0 A

<50 sec



 @5.0 A

<15 sec

  Surge life
(min operations)


@20 A

<10 sec

@10A, 10 x 1000 Ásec


@60 A

<3 sec

@100A, 10 x 1000 Ásec



10kA, 8 x 20 Ásec


  Current Limiting (-PTC) 4B1E only


@20kA, 8 x 20 Ásec


 Hold current (ma) @20C=


 @65Arms, 11 cycles, 130A total


 R min/Rmax ohms=


@10 Arms, 1 sec



1surge rating is 2x with respect to ground during a simultaneous surge
2service life requirement as per Bellcore TR-NWT-0001361
3pin alloy refers to tip and ring pins. Unless otherwise noted, all ground pins are tin

(These products were previously referred to as CT3B1E and CT4B1E.)

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