: Dkoz, I bet you'll know. Monster giant fuses. What are they to?!

10-02-08, 08:37 PM
I've got a box of fuses that are huge. They range in size of about a beer can and 400 amp/250 volt down to 60 amp/250 volt and some 600 volt/20 amp and a crapload of others. Most of them are 250 volt/70 amp.

Most of them are eco electric company, one time fuses with FPE in a red box on them. They have giant electrodes poking out of both sides (at least the FPE eco fuses do, the rest look like oversized regular tube fuses with brass ends and cardboard bodies) and weigh a lot for how big they are.

I'll try and borrow a camera and get some pictures of them up...

But I'm wondering if they're actually worth anything. If I could ebay them off and make some extra money, I could pay off some of the debt that's crushing me right now.

Any ideas?

10-02-08, 09:32 PM
They sound like master fuses from before circuit breakers were common. Fuses are a funny thing; their value is entirely intrinsic based on weather or not you need fuses. A 50 Amp circuit would have fed a whole house once upon a time. The larger ones are probably just for commercial installations. I am pretty sure they're regular items. If you've got a checker, check them to see if they're good. They're probably worth something to someone who has a system that takes them, or as collectors items if they are very old. Some people collect things like that.

The reason for the weight is that sometimes fuses like that are filled with sand or the like as cooling material. The larger ones might even have some gunpowder in them, as they act on this mechanism to ensure the circuit breaks cleanly and there is not an arcing condition in the fuse that could cause the circuit to persist while the arc carries on and burns up the linkage. This is not a problem in smaller fuses but once you get high voltages you can jump an arc fairly easily... most of yours are "medium voltage" in the true sense but 600V and up is "High voltage".

10-03-08, 01:18 AM
It sounds like an assortment of fuses that somebody maintaining a buildling would have for HVAC units and the like. They are not that expensive.

Eric Kahn
10-03-08, 05:46 PM
once fuses get over 100 amps, they start to get pricy,m the 400 amp one probably has silver in it, most large commercial fuses do, and they are filled with sand, it acts as an arc suppresor when the fuse blows along with acting as a cooling agent to give the fuse a delay factor for momentary spikes like big motors starting, starting current being 5 times running current

10-04-08, 01:26 PM
Starting current being 5 times running current

Remember this if you are sizing an Air Conditioning unit for a strictly limited power supply, like an inverter or generator...

10-04-08, 03:00 PM
Most commercial HVAC units will be three-phase powered and you can figure three times the running load for starting. There are also high lag time fuses that include a time factor that will compensate for starting loads.