My favorite topic of late - group motor installations

[petersonra]

Take a look at this photo and tell me what you think the markings mean.

I read the 60A max CB as applying only to CSA group motor applications, while in NEC applications the max CB rating in a group motor application would be based on NEC requirements, which would appear to be based on 430.53. I am still mulling over what the max rating of a CB would be in a group installation.

As best I can tell, there is no requirement in the NEC to ever have a CB less than 15A on a motor, regardless of size, so what the heck does the 6A Fuse/CB thing mean? I can't even get a 6A CB in a MCCB so does that mean you can only use this MSP on fuses? Or that if you use it on a CB it can only be used in group motor installations?

Assuming that the "acc. NEC" means that whatever the heck is in the NEC is what governs the max. SCPD size, it appears that the appropriate NEC requirement would be 430.53 (C) which has 5 requirements that have to be met. It appears there is no easy way to get around the first two requirements unless there is an actual max. CB marking on the device. Since there isn't one, how in the heck can you even use these things in a group installation other than by using 430.53 (A) or (B) which are pretty restrictive. there just does not appear to be any obvious way to take advantage of 430.53(C) at all.

 

[petersonra]

I had a long email exchange with the product manager this week and last.

He agrees with my contention that it should be labeled as max 6A fuse/15A CB. He said it was a mistake made by their German engineers. They are working on getting the labeling corrected.

The 60A group max SCPD designation does only apply to CSA. I guess you have to go through the hoops and figure out what the number is in NEC applications.

I did not realize it until an engineer at UL pointed it out to me but this particular unit is not labeled as being a self protected starter. It turns out that the S00 size is not listed as a self protected starter as are all the rest of the same line.

I looked really closely at the catalog and sure enough it does not claim the S00 units as being self protected although it is easy to miss as they boldly make that statement for the rest of them on the same page.

It turns out that because it is not a self protected starter it can be used on 480V delta systems, which UL will not allow self protected starters to do. They also apparently will not list them for tap protection except on 480Y systems, so you still have to deal with the 1/3 ampacity rule somehow in group installations (or use a 15A CB) on delta systems.