# Is it safe to go over a fuse holder voltage rating?

I am looking to buy a few online fuses and fuse holders for the mains power into a kiln I’m fixing up that runs on 240V and draws 45A. A thick 6 AWG wire connects to mains power, then is split into two 10 AWG wires in parallel per hot line. This is to connect to a terminal block with smaller connectors. This is how the manufacturer wired it, not me. If one of the 10AWG wires was to be disconnected, the full load would be pushed through just one 10AWG wire, which it cannot handle, even though it would not trip a breaker.

As a safety feature I want to add fuses to each of these smaller wires. Here is a simple diagram of how I would add them. I found this fuse holder to be suitable for my application. It has a voltage rating of 32V, but the fuse I’m using in it is rated at 300V or higher. I can’t see any problems with using this holder since it appears to be thoroughly electrically insulated and there will be no arcing at that voltage. Here’s a picture of the holder in case the listing is ever taken down. Are there any other concerns I need to consider?

• appears to be thoroughly electrically insulated ... it is insulated for 32 V – jsotola Sep 11 at 0:31
• why do you need a fuse? ... is the kiln not connected to a circuit that is protected by a breaker? – jsotola Sep 11 at 0:32
• The mains power cord is split off into two 10 gauge wires that connects to a terminal block. If one of the two becomes disconnected, then all 45A will be pushed through one 10 gauge wire, which it isn’t rated for, thus the need for the fuses. @jsotola – Ryan Sep 11 at 0:35
• now it is totally unclear what you are doing ... please add a wiring diagram to your post – jsotola Sep 11 at 0:44
• No, which part of the reason for a maximum rating don't you understand? Parallel fuses are not good practice, they may not share the current nicely. – Neil_UK Sep 11 at 5:14

## 1 Answer

If the manufacturer has rated the fuse holder for a maximum of 32V then it may be that only the manufacturer knows why it has this rating. There may be critical differences between similar looking and similarly rated fuseholders from different manufacturers, and a manufacturer might change the design of their fuseholder at any time as long as it still meets the 32V limit.

Trying to use a component outside of its manufacturer's specified maximum conditions is dangerous. You can't look at the device an tell how it will fail. The experience of someone on the internet with a similar device may not apply to what you have in your hand. These are lethal voltages you are talking about...just do it right.

• Just to add to this -- if you care enough to fuse properly, you should fuse properly, with a proper holder. – TimWescott Sep 11 at 0:38
• +1 : Use a proper fuse-holder rated for the voltage and amperage you're planning. Additionally, some more information from the holder you are looking at says it "accepts #12 to #18 wire leads" so 10 AWG won't fit. – C. Lange Sep 11 at 1:48