Should be replaced with same sized fusible link. In my 1969 Factory service manual it shows 16 Awg (1mm) dark blue for the fusible link?
The FSM also seems to show the Alternator out and largest under dash wires as 12 Awg. The 1972 might be larger like 10 Awg maybe? I think the newer cars had higher output alternators?
Anyhow, don't use a regular fast acting fuse. Temporary current surges will burn it out often.
If you want / need to use a fuse, the ANL style fuses have characteristics more like a fusible link.
Mega fuses are also more like the ANL fuse, but I think the lowest current version of Mega Fuse is like 40 Amps.
For smaller sized circuits, the Mini-ANL fuses can be bought with ratings as low as 20 Amps which is the largest I would use if going this route. Really, a replacement fusible link seems easier to me.
Because we are on the subject:
The ANL (and Maxi) fuse ratings, like 20 Amps are rated to be able to handle 20 Amps continuously without burning out, and only burn out when the current exceeds the rating for an amount of time. The Specs say the fuse will allow 150% current rating for about an 1 Hour (min), so 30 Amps could flow through the fuse for an hour plus before blowing.
The higher the over-current, the faster the fuse blows. At 160% (32 Amps) the fuse could blow in 6 seconds minimum.
Specs say 220 % overcurrent (44 Amps) the fuse will allow that much current for 60 seconds Maximum.
If you had a bad short circuit, specs says a 400% rating (80 Amps) the fuse will blow in less than 2 seconds.
Anyhow, the Fusible link acts alot like the ANL fuse allowing some over current conditions / surges to happen without burning out.
In Google, entering "time current characteristics of anl fuse vs fusible link" resulted in this AI response:
When comparing the time-current characteristics of an ANL fuse and a fusible link, the key difference is that a fusible link generally has a slower response time than an ANL fuse, meaning it takes longer to melt and break a circuit under high current conditions, as fusible links are designed to handle short-term overcurrents while still providing circuit protection in critical situations; whereas an ANL fuse is designed to blow quickly when a significant overcurrent occurs, providing faster circuit interruption.
Key points to remember:
- Fuse Response:
ANL fuses usually have a faster "time-current characteristic", meaning they will blow more rapidly when a high current is present compared to a fusible link.
- Fusible Link Purpose:
Fusible links are often used in situations where a momentary high current surge is expected, like during motor start-up, and are designed to handle these surges without blowing immediately.
- Rating Differences:
While ANL fuses have a clear amperage rating, fusible links are often not rated in amps as their function is more dependent on the specific circuit and the intended current handling capacity.
