6.3 Amp limitation

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ReneDionne

Member
Location
Montreal
Occupation
Engineer
Hello. I have some Entrelec/ABB fuse terminals that show a 6.3A max fuse that I can put in. However, on the little table that is etched on the side, under the CSA column (I am in Canada), I can clearly see 10A. I can provide a picture later, but I am just confused because this appears to be contradictory to me. I want to use a 10A fuse to distribute power to 3 discrete output PLC cards (triac) at 120 VAC. Would the be a code violation? Space is limited in my panel. Has someone ever been exposed to that situation? Thanks in advance.
 
Cannot seem to be able to attach a photo for now, but I think the explanation above should be clear enough. The fuse holder terminal is an M4/8SF. Let me know if you have any info on the fuse limitation. Thanks.
 
Thanks for the reply. Indeed, I saw that too, which goes with what is printed on the body of the terminal. My observation (and this is purely personal, and I hope my cognitive bias is not playing tricks on me) is that since this was originally an Entrelec Terminal (European) the IEC rating is what is printed on the mobile "holder" part, and there was no amp rating under the CSA column, only voltage and AWG. Then, at some point it was finally tested by CSA (and UL) to 250V/10A (and 600V/15A for UL). They modified the manufacturing process to include the CSA Amp rating... but they kept the big 6.3A marking on the mobile fuse holder... which brings confusion. Unless the marking on the terminal is the rating inside the terminal (bus bars), and the rating on the mobile holder concerns only the holder? Has anyone been challenged by this situation?
 
It is pretty common for UL and IEC specs to be different for the same part. One of the common ones is a part might have an IEC rating of 690 Volts but a UL rating of 600 Volts.

There are some strange rules about fuse sizes in IEC specs. For some fuses and devices 6.3 Amps is it.
 
Fuses have resistance and therefore produce heat. It might just be that in IEC listed fuses, the fuse size (5 x 20mm) that fit these blocks only go to 6.3A @630V max. with regard to the heat they create within the allowable heat rise parameters of the IEC rules. But in CSA they can go to 10A (IF you use 12ga wire) @ 250V max., whereas if you use it in the US with UL listing, it can hold a 15A fuse @ 600V using 12ga wire. That would imply that the different testing standards have different heat rise limits.
 
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