Replacement fuse for a Dewalt 788

[Kelly Colin Mark]

I was all set to meet somebody to sell him my Dewalt 788 scroll saw. It worked like a top the last time I used it. Brought it down from my cottage to the city to sell it. It's a good thing I decided to power it on at home because it wouldn't start. Somewhere on the way home the fuse holder popped out, and the fuse got lost.

The manual says "Your scroll saw uses fuse #3AG Fast Acting,1 1/4" long x 1/4" diameter".

I'm in Canada and checked Canadian Tire's website because they sell a lot of hardware and automotive parts - couldn't only find a few fuses listed. Also checked Home Depot - nothing but big fuses.

Where would someone go to buy something like that ? Electrical supply house ?

[Duane Meadows]

Radio Shack? 3AG are quite common, but what amperage? Amazon also has 3AG fuses.

[Myk Rian]

Get them at an auto supply store.

[Kelly Colin Mark]

I should have copied the whole paragraph from the manual. It's a 3A fuse.

Thanks Duane and Myk. Will visit the auto department at our local Canadian Tire store, or the Source (what the RadioShacks in Canada are now called).

[Rollie Meyers]

Get them at an auto supply store.


You need a fuse rated for the correct voltage & automotive fuses are not.

[Duane Meadows]

In either case, the insulator is a 1/4" x 1 1/4" glass tube... I don't really think there is much if any difference. A 3AG fuse is pretty much a 3AG fuse.

[Myk Rian]

You need a fuse rated for the correct voltage & automotive fuses are not.
Sure they are. A glass 3AG fuse is often used in electronics, on the power in side of the circuits.

[Rollie Meyers]

Sure they are. A glass 3AG fuse is often used in electronics, on the power in side of the circuits.

The automotive fuses may only have a 32 volt rating, as long as they have the proper voltage rating then it does not matter where they come.

[Ken Fitzgerald]

3AG fuses is a pretty standard fuse. You need the voltage and current rating off the existing fuse and take it to an electrical or electronic supply place. Radio Shack typically carries them. Here in the States, it is easy to find the 3AG fuses but the metric sized ones are difficult to locate.

[Kelly Colin Mark]

3AG fuses is a pretty standard fuse. You need the voltage and current rating off the existing fuse and take it to an electrical or electronic supply place. Radio Shack typically carries them. Here in the States, it is easy to find the 3AG fuses but the metric sized ones are difficult to locate.
Ken,

Unfortunately I don't have the original fuse - when the carrier popped out in my trunk, the fuse must have rolled out somewhere - I certainly can't find it. The Dewalt specs don't seem to specify a voltage. I put a loupe on the replacement fuses I bought and they say 3A/250VP... I know the first part says is a 3A fuse, but have no idea what the second part means ??? A fuse cross-reference I just found says it's a 32V, fast-acting fuse.

[Rollie Meyers]

Ken,

Unfortunately I don't have the original fuse - when the carrier popped out in my trunk, the fuse must have rolled out somewhere - I certainly can't find it. The Dewalt specs don't seem to specify a voltage. I put a loupe on the replacement fuses I bought and they say 3A/250VP... I know the first part says is a 3A fuse, but have no idea what the second part means ??? A fuse cross-reference I just found says it's a 32V, fast-acting fuse.


If they are 250V rated your fine.

[Kelly Colin Mark]

Thanks everyone. Sold the saw with one of the replacement fuses the other day (forgot the rest of the pack at my cottage). Wouldn't have felt good about it without the advice from the good people here !

[Duane Meadows]

What part of a fuse exactly, has to withstand 250V? The voltage drop across a good fuse is near zero. The insulation to chassis/frame is a function of the fuse holder, not the fuse. A blown fuse blew to the point no more current will flow through it at the applied voltage due to the amperage through it, not the voltage with respect to surrounding components.

I know they are sold with voltage ratings, but really I can't see any way it matters. Been in electronics for over 35 years, still don't understand that one. Other types? Perhaps. 3AG? Gimme a break. Have never seen an instance where the voltage rating mattered. Seen a very, very few crack the glass from a lightning strike, but way more than 250V involved there.

[Ken Fitzgerald]

Duane,

It's been 40+ years since I studied the theory. I honestly don't remember.

But here's what Wikipedia says:

Rated voltage[edit (http://www.sawmillcreek.org/w/index.php?title=Fuse_(electrical)&action=edit&section=8)]Voltage rating of the fuse must be greater than or equal to what would become the open circuit voltage (http://www.sawmillcreek.org/wiki/Open-circuit_voltage). For example, a glass tube fuse rated at 32 volts would not reliably interrupt current from a voltage source (http://www.sawmillcreek.org/wiki/Voltage_source) of 120 or 230 V. If a 32 V fuse attempts to interrupt the 120 or 230 V source, an arc (http://www.sawmillcreek.org/wiki/Electric_arc) may result. Plasma (http://www.sawmillcreek.org/wiki/Plasma_(physics)) inside that glass tube fuse may continue to conduct current until current eventually so diminishes that plasma reverts to an insulating gas. Rated voltage should be larger than the maximum voltage source (http://www.sawmillcreek.org/wiki/Voltage_source) it would have to disconnect. Rated voltage remains same for any one fuse, even when similar fuses are connected in series. Connecting fuses in series does not increase the rated voltage of the combination (nor of any one fuse).