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Inverter Fuses - Amps and VOLTS?

Maybe someone could give me a definitive answer on this:

In my car I was using a 300-watt power inverter which provides power by being plugged into the cigarette lighter plug. The power inverter was doing fine for years until I absent-mindedly plugged in a 500-watt electric teapot recently and blew the fuse in the inverter.

The blown glass-type fuse that I removed had 15A imprinted on the side, but when I searched for a 15-amp glass fuse replacement at the local electronic store, I have a choice between a 32-volt 15-amp glass fuse and a 250-volt

15-amp glass fuse. The ubermensch in the electronic store experienced a "duh" moment and ambled back off to his tar pit when asked about the significance of the voltage difference, so I was none the wiser for his valuable assistance. There doesn't seem to be any documentation or reference anywhere, either with the inverter or on the Internet (that I can find) that addresses this issue.

So, 32-volt vs. 250-volt - what's the essential difference and which do I need in this case? Will 32-volt blow immediately once I plug anything into the inverter, or will 250-volt NOT blow and wreck some piece of equipment that the fuse is supposed to protect? Thoughts? Thanks in advance!

Reply to
Helpmeister
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Fuses are rated to the voltage of the circuit they protect. In this instance you will need to determine which part of the inverter the fuse protects. Sounds like the low voltage input from the current stated, so go for the

32volt if cheaper, the voltage rating does not affect the current the fuse blows at so either will work OK. 
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Reply to
Rheilly Phoull

A fuse's voltage rating tells you how much voltage it can interrupt when it blows. Since a 15 amp fuse would have to be on the 12 volt side of the inverter, either rating will easily extinguish the arc caused by the 14 volts or so from the battery.

Don't be too surprised if you discover that the fuse did not blow to protect the inverter from damage, but to protect the wiring after the inverter was destroyed by the overload.

Reply to
John Popelish

What voltage was marked on the one you took out and was it in the plug that fits in the cigar skt?

Are you sure it's a 300W inverter?...

15A x 12V = 180W

What country are you in?

If the output is 220-240V (eg for the UK/Europe) could the fuse be a 1.5A (1 point 5 Amps) ?

1.5 x 230 = 345 W
Reply to
CWatters

I believe most inverters advertise their peak output power up front, and then unobtrusively reveal their (much lower) continuous output power somewhere in the manual. And since a "fast blow" fuse will withstand twice its rated current for some time, it's possible that the inverter can transmit 300W briefly with that fuse. A TV, for example, can pull a surge current when you power it up before settling at a lower level of power consumption.

Reply to
deneb

Never thought much about this before. If a 250V fuse were not different in some way that was detrimental to the low voltage circuit, there'd be no reason to have a 32V fuse. Is the 32V fuse lower resistance? Or maybe it's just the added cost of the springs that insure the distance between the ends of the blown 250V fuse?

mike

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Reply to
mike

Which just makes a 500W kettle an even bigger overload :-)

Reply to
CWatters

I am not an expert on fuse construction. It stands to reason that it is easier to make a mechanism that is certain to block 32 volts than it is to make one that blocks 250 volts. I think you should open a few different kinds and see what you can discover about their differences.

Reply to
John Popelish

The voltage rating on a fuse comes into play the moment the fuse opens. If a low voltage fuse is use in the place of a 120Volt or 250Volt fuse, the fuse will arc across the gab for a longer period of time than would a fuse of the appropriate voltage rating. Typically, it is not a problem to use a fuse with a higher voltage rating in a low voltage application.

Reply to
DBLEXPOSURE

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