Triumph Repair: 72 Spitfire MK IV, ballast resistor, spitfire mk

Question
Howard,  While troubleshooting backup lights I noticed my ignition coil and ballast resistor became extremely hot. In fact, the plastic spade insulators on the ballast resistor began smoking. This happened after the ignition switch was left on for about 15 minutes. Is this normal? If not, what should I check? Coil & resistor are cool while engine is running. Thanks.

Answer
Hi Chuck,
It is not uncommon for a coil and resister to get extremely hot if left on for any length of time if the contact points are closed. The resister nor the coil were designed to handle continuous current. Any time you have to leave the ignition switch in the "On" position to do any work you should either check to see that the points are open or just unplug the power wire of the coil.
Howard