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Triplett Line-Bug 4 (Catalog # 9615)

General Description

The Triplett Line-Bug 4 is intended to test for the presence and polarity of telephone current on circuits terminated in an RJ-11 or RJ-45 connector

The Connectors

• An RJ-11 is the common connector used for telephone, often called a 'modular' jack or plug.
• An RJ-45 is a jack, originally used for telephone, but now commonly used for LAN systems.
• The Line-Bug 4 has both an RJ-11 and an RJ-45 plug, allowing it to plug into either type of jack.

The Switch
Since the RJ-45 has been used for both telephone and LAN connections, the switch on the front of the Line-Bug 4 allows the user to select which type of connection will be tested. Setting the switch to 'USOC' configures the RJ-45 plug on the Line-Bug 4 to test per the telephone wiring standard. Setting the switch to '568 A/B' configures the RJ-45 plug on the Line-Bug 4 to test per the LAN wiring standard. The setting of the switch has no effect on the RJ-11 plug.

The Indicator Lights
The indicator lights show the presence and polarity of the circuit that the Line-Bug 4 is plugged in to. If any light turns on, a telephone circuit is present on the wires corresponding to the illuminated light.

An RJ-11 circuit can have as many as 3 circuits present.. so 1, 2, or 3 lights may come on with a "good" circuit, with each illuminated light indicating the presence of a telephone line. If the lights are Green, the polarity is normal. If the lights are Red, the polarity is reversed. Often, telephone circuitry will work OK with reversed polarity, so, in general, a Red light is not a reason for concern. If no lights come on when the RJ-11 plug is connected to a mating jack, the jack is either disconnected from telephone service, or it is wired differently than a standard telephone jack.

An RJ-45 circuit can contain as many as 4 telephone lines... so 1, 2, 3, or 4 lights may come on. As before, if the lights are Green, the polarity is normal. If the lights are Red, the polarity is reversed. If no lights come on when the RJ-45 plug is connected to a mating jack, move the switch to its opposite position and see if any lights come on. If lights do not come on in either position, the jack is either disconnected from telephone service, or it is wired differently than 568 A/B or USOC.

Telephone lines cause a telephone to ring by rapidly reversing the polarity of the telephone current. This causes the light on the Line-Bug 4 to rapidly change color from Green to Red. and it looks Amber. When a pulsating Amber light is seen, the phone line is ringing. Care should be exercised when testing a ringing telephone line. In addition to reversing the current, the voltage is also boosted. A ringing telephone line can deliver a pretty good electrical shock. so be careful.

LAN Systems and Telephone Lines
The RJ-45 connector used for the typical 10MHz or 100MHz LAN system only uses 4 of the 8 wires in the connector. In some localities, the 4 unused LAN wires are being used for telephone circuits. That means an RJ-45 jack can have a LAN connection and 2 telephone lines all on the same jack. The jack can provide LAN service, telephone service, or both.

Many LAN Test Sets were not designed to be connected to telephone lines. An unprotected Test Set can be damaged by inadvertent connection to a telephone line. The Line-Bug 4 gives the LAN Test person an inexpensive way to determine if telephone current is present on an RJ-45 connection, before plugging his expensive LAN Test Set in.

Using the Line-Bug 4
Using the Line-Bug 4 is very simple.

• Plug it into the circuit to be tested. Use the plug (RJ-11, the 'small' plug. or RJ-45, the 'big' plug) that fits the circuit to be tested.
• Observe the lights. If testing an RJ-45 connection, move the switch to both positions and observe the lights. A light will light for each telephone circuit present. Interpret their meaning:
  • No Light: Dead Circuit (As far as telephone is concerned. It may be a live LAN connection)
  • Green Light: A telephone line is present in the correct polarity
  • Red Light: A telephone line is present in reversed polarity
  • Amber Light: A ringing telephone line is present

Frequently Asked Questions

Q: Does the Line-Bug 4 tell me if a LAN jack is connected to a LAN system?
A: No. The Line-Bug 4 only tests for telephone current. It does not test for the presence of a LAN signal.

Q: Does the Line-Bug 4 tell me if the line is a 'digital' phone line.
A: No. The Line-Bug 4 will often light up on a digital phone line, as is not damaged by the digital line, but nothing gives an indication to the user that the line is digital.

*Note: Products designed to work on analog telephone lines are often damaged when plugged into digital phone lines. Digital phone lines are seen most often in hotels and businesses.

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