Re: 1930 (and many other years) fuse block

Posted by 32model901 On 2010/10/3 15:12:25

Tom,

The mica sheets are primarily for support of the wire that is wrapped around them. At the time mica was one of the only materials that would stand up to the heat.

As you know this fuse block has a glass fuse in parallel with the wire wrapped around the mica. If there was a short in the system the fuse would blow and the wire wrapped around the mica would get red hot.

The glass fuse would open but the wire wrapped around the mica would still permit current flow, so the engine wouldn't stop, unless the short was in the ignition system.

Since the resistance of the wire wrapped around the mica increases greatly when it gets hot, the current flow from the generator to ground would actually decrease, protecting the generator from burning itself up.

Pretty smart, those Packard Engineers......

Regards,

Dave