What is a sign connector?
The sealed plug-in joints in a sign's circuit: primary connectors that join the transformer to the loop, and a secondary connector that joins it to the sign.
A sign is not hard-wired into the airfield circuit. It is joined through sealed plug-in connectors, so a sign can be disconnected, tested or replaced without re-jointing the main cable. Each sign has two kinds, on the two sides of its isolation transformer, and they do different jobs.
1Primary connectors, in the loop
Two primary connectors join the transformer's primary leads to the series loop cable, one in and one out. They are links in the loop, so they carry the full circuit current. Unplugging either one opens the loop and stops every light on it, and one poor joint here can affect the whole circuit, not just one sign.
2Secondary connector, to the sign
The secondary connector joins the transformer's short secondary cable to the sign. It lets the sign be removed, swapped or tested on its own. Because the secondary is isolated from the loop, the loop stays closed when it is unplugged. Treat the secondary as live all the same: an isolation transformer with an open secondary on a live circuit can develop a high voltage, so the secondary is unplugged only with the circuit isolated, locked out and proved dead.
3Sealed and checked
Connectors sit in the base can or sign base and are sealed against water, because moisture in a joint is a common cause of insulation faults. They are keyed to mate one way, checked for a full seat and clean contacts when installed, and included in inspection and insulation-resistance testing.
| Element | Detail |
|---|---|
| Primary connectors | Two per sign: loop in and loop out, carrying the circuit current |
| Secondary connector | One, between the transformer secondary cable and the sign |
| Housing | Base can, transformer pit or sign base |
| Seal and fit | Waterproof and keyed to mate one way |
| If it fails | Primary: the whole loop can be affected. Secondary: that sign only |
| Checks | Full seating, seal, contacts, insulation resistance |
Frequently Asked Questions
Q1What is a sign connector?
A sealed plug-in joint in a sign's circuit. Each sign has primary connectors that join its transformer to the series loop, and a secondary connector that joins the transformer to the sign.
Q2Why are there two kinds of connector?
They do different jobs. The primary connectors sit in the series loop and carry the full circuit current. The secondary connector sits on the isolated side and feeds only that one sign.
Q3Is it safe to unplug a sign connector?
Not without isolating the circuit first. Unplugging a primary connector opens the series loop and stops every light on it, and the secondary should be treated as live, because an open-circuited secondary on a live circuit can develop a high voltage. Isolate and make the circuit safe under site procedures before any work.
Q4What goes wrong with sign connectors?
Water getting into a joint, a connector that is not fully seated, or dirty or damaged contacts. In the primary, one poor connection can affect the whole circuit, so connectors are checked during installation, inspection and insulation-resistance testing.
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