Old Britts – Positive Ground Rectifier Replacing Lucas 49072
Download the complete PDF version using the green download button at the top right of this page for an Old Britts electrical reference covering the positive ground rectifier used to replace the Lucas 49072 unit on Norton Commandos. This guide identifies the replacement rectifier, explains the terminal layout and provides clear wiring notes for connecting the alternator, battery and ground leads correctly.
The article explains that this style of rectifier may have either three or four terminals. Two terminals connect to the alternator leads, the center terminal connects to the negative battery wire and the fourth terminal, when present, serves as the ground connection together with the mounting stud. The guide also makes clear that the two alternator wires may be connected to either alternator terminal.
The final section lists the commonly used Norton Commando wire colors for this installation, including Brown/White or Brown/Blue for the battery lead, Green/Yellow and White/Green for the alternator wires and Red for the ground wire. Photographs show the replacement rectifier from several angles with the relevant terminal positions clearly identified.
Contents Include
- Positive ground rectifier replacement for Lucas 49072
- Old Britts part number 17-49072/R reference
- Three-terminal and four-terminal rectifier layouts
- Center battery terminal identification
- Alternator terminal connection guidance
- Ground terminal and mounting stud explanation
- Commando wire color reference
- Brown/White and Brown/Blue battery lead notes
- Green/Yellow and White/Green alternator wire notes
- Red ground wire identification
