Electrical wiring/stereo question

[Michael_Bird@xxxxxxxxxxxxxxx]

First:   Thank you Richard Welty!     Now, if only we can remember not to
ask...

Now my question:   I was at a local electronics store last night.  For sake
of example, let's call it Circuit City.   I was looking at getting a new
stereo for my E28, and was talking with the installers about the
requirements for an amplifier.  This amp would be around 400 watts (peak),
and he recommended a 4 AWG wire with an 80 AMP fuse.   The last time I did
something like this (back in the eighties, when BMW owners were yuppies,
not the sophisticates that we are now) I ran two large amps and a crossover
off of a single 30 (fused) Amp circuit using 10 AWG wire, with no problems.
The young man at CC was trying to tell me that with 4 AWG that the wire is
so large, even if the amp is not on (not drawing power), a 30 amp fuse
would blow the minute you plug it in.   I just don't get it.   That's not
how I understand electricity to work.   He also was adamant that nothing
less than 4 AWG would do the job.  I think that's overkill.   I also told
him that the car would be on fire before an 80 AMP fuse would blow.   I
also wonder if the electrical system would even produce 80 amps?   But he
was young, and maybe he knows something I don't...

So, do any of you guys/gals have any thoughts?  Am I right?  If not, can
you explain it to me in layman's terms?   I am assuming that there are
enough youngsters and oldsters alike (I fall in-between, thank you very
much) that this would be of general interest, but if I am mistaken, I
apologize (and you may answer privately).

Question #2 :  Removing the stock head unit from dash: there appears to be
two allen head bolts holding it in, somewhere between 2 and 2 1/2 mm.
None of my various metric and standard allen wrenches will fit.
Suggestions?   Special tool?

Many thanks in advance, or MTIA as some might say.

Michael

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