Interesting take Paul, but normally an overrating is an unpublished
overrating. Normally a design factor is built into any mechanical or
electrical device so that when the user plugs in his numbers, the
numbers stand a better chance of working than if the published numbers
are really at the limit of performance. Typically the NEC will rate a
certain number of a particular gauge wires allowed in a certain size
conduit with a specific percentage chopped of the top in order to ensure
that in case of overload, the installation should not fail. I would be
VERY surprised if the TRUE fail load was stamped on the fuse.
On rigging equipment the actual fail value is never stamped on the
equipment. There is always a design factor built into the load limit
even if the manufacturer is China or Taiwan. My take on buying Chinese
rigging bits is that I build a design factor of 5 to 1 from the stated
working load limit and never buy Chinese if I'm working with live loads
or flying people.
I'm trying to come to this same understanding of fuse design and rating.
I have noticed that no one has addressed Ohm's Law. I've been inundated
at work and putting up what turned out to be a very successful car show
this weekend in Nashville and can't wrap my head around it.
Will a fuse rated for 15 amps at 32 volts blow at about the same energy
level as a fuse rated for 35 amps at 12 volts?
Glenn
> Perfectly understandable, but the fuse wire in these is over an inch long,
>> even 20kV or so from the ignition coil couldn't jump the end caps or even
>> keep an arc going. I've got fuses labelled 250v which are less than half
>> that length. The lowest voltage quoted on that site is 125 volts (and the
>> others are all round numbers), also quite reasonable. 32 volts is a
>> ridiculously low voltage to quote for those fuses, as well as being a very
>> odd value. Blade fuses have the same rating even though the spades are
>> much closer together. It seems to me that someone has labelled all
>> automotive fuses as '32 volt' which is perhaps nothing more than a typical
>> maximum of 24v plus a safety factor, without any regard to what they are
>> actually safe at. None of my fuses show a voltage rating, only a current
>> rating. The upshot is that you can fit any fuse of the correct physical
>> dimensions *and current rating* regardless of its notional voltage rating.
>>
>> PaulH.
--
Glenn Schnittke
-----------------------
g.schnittke@comcast.net
Home - 615-837-5883
Cell - 615-319-5534
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