On 19/12/2015 23:44, JD wrote:
replying to Peter Andrews , JD wrote:
pa wrote:

Yes a fuse is essential, use an in line one close to your crocodile
clip, not that I approve of your method of connecting to the battery.
Without a fuse you run the risk of a few meters of glowing red hot
wire - been there and done it, albeit 50 years ago! Peter

I agree about the crocodile clip; I securely clamped the wire instead.
Surely, the bulb itself will act as a fuse, won't it? I couldn't find an
inline fuse today, so I wired it up with no fuse. Why would the wire get
red hot?

Are you a mechanical superhero, incapable of making mistakes?

If so, leave the fuse out.

If you're a normal human being, put one in, because that way when you
accidentally short the wire onto something (not entirely unlikely) the
fuse will blow rather than you ending up with a red hot wire dripping
insulation all over your nice engine bay.