2 fuses and branch breakers series rating

[electrofelon]

If D is the only thing that is not fully rated, then either A, B or C must be series rated with D for this to be ok.

E and F don't matter since they are fully rated downstream of D.

But that brings up more questions... from previous conversations and Eaton's option 4

Is it acceptable to use A, B, C, D, E, F in series in this scenario?:
B rate with A, C rate with A, D rate with A, E rate with A, and F rate with A

B, C, D, E, F don't rate with each other

Well that's just the infamous option 4 we have been discussing the last several dozen posts isn't it? I would say based on the Eaton document it is perfectly fine.

 

[Tainted]

Well that's just the option 4 we have been discussing the last several dozen posts isn't it? I would say based on the Eaton document it is perfectly fine.

The only difference is they used 3 different overcurrent protections, that's why I brought it up.

 

[electrofelon]

The only difference is they used 3 different overcurrent protections, that's why I brought it up.

IMO that is just an example and there is not a restriction on using no more than three devices.

 

[wwhitney]

Going to just stop you there because I have an issue with "is sufficient for the AFC at D". I don't really know what that means.

If you like, C has an AIC rating, D has an AIC rating, and then if (C,D) is series rated, D gets a "joint" AIC rating when used with C just upstream. I gather that usually that joint AIC rating is the AIC rating of C, and you just say C and D are series rated, but there's no particular reason the joint AIC rating has to match C's AIC rating. So all I was saying for my example is that the joint rating for (C,D) is greater than the AFC at D.

Cheers, Wayne