Electrical: Fuse question

[TomMar]

The passing lamps on my '06 Midnight Venture went out. The fuse is a 10amp/32v glass fuse. Can I use any 10amp glass fuse, i.e. 10a/125v, or does it HAVE to be a 10a/32v??

 

Thanks,

[dingy]

You can safely use 10A/125V fuse in place of the 10A/32V fuse.

 

The voltage rating is a maximum value that the fuse should be operated at.

 

It does not change the current value of the rated fuse value.

 

Gary

[CMIKE]

:sign yeah that:What he said.

I was involve in a Coast Guard inspection and the inspector requested I pulled out a fuse from the general alarm system, He looked at it and proceeded to write me up because I had a 125V 5 amp fuse in a 24VCD system. We argued and argued about this. The inspector won over and still wrote us up cause his little book said the fuses should be 32VDC fuses.

We had to go to New Orleans before a Coast Guard board to argue our point and finally after a 1/2 day discussion with engineers and the Coast Gaurd, got the fine resended.

 

So you are good on the higher voltage fuses. Actually the 125 V is a better fuse than the lower voltage fuse.

[Nemo]

Well, Volts times Amps equal Watts - so a fuse of 10 Amps at 125 Volts could supply a load of 1250 Watts. But a fuse of 10 Amps at 32 Volts would only supply a load of 320 Watts and would blow if used for 125 Volts. In other words, your 125 Volt fuse would not blow from an overload up to 1250 Watts.

[GOODWRENCH]

I hope your alittle less con-fused after all that. By the way I have family living in Hartley and an uncle that used yo live in Milford,love it down there,mght retire there or Middletown.

[dingy]

Well, Volts times Amps equal Watts - so a fuse of 10 Amps at 125 Volts could supply a load of 1250 Watts. But a fuse of 10 Amps at 32 Volts would only supply a load of 320 Watts and would blow if used for 125 Volts. In other words, your 125 Volt fuse would not blow from an overload up to 1250 Watts.

 

 

That doesn't apply in this case.

 

Ohm's law is not involved in a voltage rating for a component.

 

1 amp of current flow is the same regardless if is at 12VDC or 120VDC.

 

The circuit resistance would be increased by a factor of ten due to the 10 fold increase in voltage. But an amp is an amp at any voltage.

 

Current flow is a measurement of electrons flowing past a point in a circuit. This flow of electrons creates heat. This heat is what causes the fused link to melt and open the circuit.

 

Gary

[Flyinfool]

 

Where the voltage rating comes in is if you were to use a 32V fuse in a 120V application, the voltage would not cause the fuse to blow. The fuse will still not blow till the rated Amps are reached. The problem is that even though the 32 volt fuse did blow in the 120V circuit, it may not be able to stop the flow of current. The voltage rating the the MAXIMUM voltage that the fuse can reliably interrupt.

[Owen]

Let me throw in my two cents worth...

The voltage rating has nothing to do with the current level that will open the fuse.

 

The voltage rating is the max voltage that will not arc across the open element of the fuse after it is blown. That's my 'plane speak' explanation. In other words, an open 32v fuse could possible arc across the open element if the voltage of the circuit is higher, such as 125v or 250v.

 

Here is the technical explanation:

VOLTAGE RATING: The voltage rating, as marked on a fuse indicates the fuse can be relied upon to safely interrupt its rated short circuit current. in a circuit where the voltage is equal to, or less than its rated voltage. This system of voltage rating is covered by N.E.C. regulations and is a requirement of Underwriters Laboratories as a protection against fire risk. The standard voltage ratings used by fuse manufacturers for most small dimension and midget fuses are 32, 125, 250 and 600. Short circuit interrupting capacities may vary with fuse design and range from 35 amperes AC for some 250V metric size (5 X 20mm) fuses up to 200,000 amperes AC for the 600V KLK-R series. information on other fuse series can be obtained from the factory. In electronic equipment with relatively low output power supplies and circuit impedance limiting short circuit currents to values of less than ten times the current rating of the fuse. It is common practice to specify fuses with 125 or 250 volt ratings for secondary circuit protection of 500 volts or higher.. As mentioned previously (See DERATING) fuses are sensitive to changes in current, not voltage maintaining their "states-quo" at any voltage from zero to maximum rating. It is not until the fuse wire reaches melting temperature and arcing occurs that the circuit volt age and available power influence the fuse performance and determine the safe interruption of the circuit. To summarize a fuse may be used at any voltage less than its voltage rating without detriment to its fusing characteristics, but may also be used at voltages higher than its certified voltage rating if the maximum power level available at the fuse under a "dead short" condition can only produce a low energy level non-destructive arc, fuses listed in accordance with UL Standard 198G are required to have an interrupting rating of 10,000 amperes with some exceptions (See STANDARDS SECTION) , which in many applications provides a safety factor far in excess of the short circuit currents available.

 

That's my story and I'm sticking to it.