I’m working on a fault current calculation for a meter stack and had a question regarding series ratings.

According to the manufacturer, the Siemens QPH breaker can be series-rated with a Siemens 3VA6-H breaker, resulting in a load center feeder breaker with a 100kA AIC rating. Additionally, a Siemens QP breaker can be series-rated with a QPH breaker at 22kA.

My question is: if the feeder breaker (QPH) is part of a series combination rated at 100kA with the upstream 3VA6, can the downstream branch breakers (QP) also be considered as having a 100kA series rating? Or are they still limited to their own tested series rating (22kA with QPH)?

You would have to look in Siemens tables to see if the breakers "stack". However, I doubt it...best to double check.

Mike

75kA available looks pretty high but not enough info to really evaluate. Are you confident in that value?

Also what Mike said RE: series ratings. Eaton has some info on tenant rating like what you have there with 3 breakers but the answer is what Mike said. You might be ok if the QP also has a rating with the 3VA6 but you'll need to look it up.

From Eaton. Siemens may be different: