What class fuse for a 2kva transformer?

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Kilowatt#76

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Hi,

What class fuses for a 2kva transformer? I have always used class cc fuses and is there a standard used for what types can be used?

Thanks,
Pete
 
Kilowatt#76 said:
Hi,

What class fuses for a 2kva transformer? I have always used class cc fuses and is there a standard used for what types can be used?

Thanks,
Pete
Click to expand...
If the current rating is adequate class cc fuses are code compliant. Personally, I would use transformer fuses on the line side. FNQ-R fuses are class cc fuses but have a different tc characteristic so they are better suited for the line side of a xfmrs than an LPCC fuse. You could also use any other branch circuit rated fuse such as a class j.
 
petersonra said:
If the current rating is adequate class cc fuses are code compliant. Personally, I would use transformer fuses on the line side. FNQ-R fuses are class cc fuses but have a different tc characteristic so they are better suited for the line side of a xfmrs than an LPCC fuse. You could also use any other branch circuit rated fuse such as a class j.
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Cool deal, thanks!
 
petersonra said:
If the current rating is adequate class cc fuses are code compliant. Personally, I would use transformer fuses on the line side. FNQ-R fuses are class cc fuses but have a different tc characteristic so they are better suited for the line side of a xfmrs than an LPCC fuse. You could also use any other branch circuit rated fuse such as a class j.
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LP-CC fuses were developed from the FNQ-R in order to better handle motor starting current. They are more expensive than FNQ-R and since the load is a transformer, I wouldn't waste the money on them. Class J are "better" if you have sensitive equipment, but are even MORE expensive and unnecessary for transformers. Yes, you CAN use them, but again, kind of a waste of money in this application. FNQ-R (or an equivalent from another brand) are the optimum choice for small transformer primaries.

A word of caution here. These fuses are the same physical dimensions of other "midget" fuses, but many of those are NOT listed as "Branch" protection, meaning they must be used as "supplementary" devices behind OTHER branch protective devices. People often assume that if they fit, they can be used. Not so. The fuse must say Class CC to be used as a branch device.
 
Class j fuses cost us about the same as class cc. The only real difference is that class cc fuses only go to 30 amps (in some cases 35). I use class CC fuses because there are some neat bus bar accessories available.

Midget fuses will not fit in a class cc fuse holder but class cc fuses will fit in a midget fuse holder.
 
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