Let me preface my question by saying that I do have a pretty solid understanding of household electrical wiring. A few years ago I did all of the wiring from meter socket to main panel to outlets for the 200 amp service in my workshop so I do have some experience under my belt in how to add circuits to a main service panel. When it comes to adding a 50 or 60 amp sub panel I start to have some questions.
Here's the scenario, I am ready to restart my kitchen remodel and am in need of 2 new additional 20 amp circuits beyond what I have room for in the main panel (I have open breaker slots but the neutral bar is maxed out). Back in January we had a new HVAC system installed and as a result of that we were "gifted" with a now unused 50A 240V circuit terminated in a fused disconnect directly under the kitchen in the crawlspace. At the time I thought that would be huge help and that I could just turn that into a sub panel to feed the new circuits, location is ideal because getting wiring to that location from the main panel is nightmare due to the configuration of the walls and floors between them in our split ranch. The problem with that plan I have now discovered is that it is not wired with a 4 wire cable so I don't have a dedicated ground running back to the main which I understand is required for sub panels. I also realized that having the breakers for these two circuits located in the crawlspace is far from ideal so I decided it would be best to eliminate that circuit completely, pull a new 6/3 cable into the main panel and locate the sub panel in a more convenient location. So that's a very long story to get to my main question...
I know that the the neutral and ground bars need to be separate in the sub panel, with the ground bar bonded to the box, and that you need to have separate neutral and ground wires running back to the main panel along with the 2 hots. That's where the confusion hits me, my main service panel does not have separate neutral and ground bars. So does that mean I can't add a sub panel since I can't separate the neutral and ground in the main panel? If that's the case, I'm thinking the best course of action would be to add a separate ground buss, bond it to the panel and move all of the existing equipment grounds to it from the neutral buss to free up the space I need?
Here's the scenario, I am ready to restart my kitchen remodel and am in need of 2 new additional 20 amp circuits beyond what I have room for in the main panel (I have open breaker slots but the neutral bar is maxed out). Back in January we had a new HVAC system installed and as a result of that we were "gifted" with a now unused 50A 240V circuit terminated in a fused disconnect directly under the kitchen in the crawlspace. At the time I thought that would be huge help and that I could just turn that into a sub panel to feed the new circuits, location is ideal because getting wiring to that location from the main panel is nightmare due to the configuration of the walls and floors between them in our split ranch. The problem with that plan I have now discovered is that it is not wired with a 4 wire cable so I don't have a dedicated ground running back to the main which I understand is required for sub panels. I also realized that having the breakers for these two circuits located in the crawlspace is far from ideal so I decided it would be best to eliminate that circuit completely, pull a new 6/3 cable into the main panel and locate the sub panel in a more convenient location. So that's a very long story to get to my main question...
I know that the the neutral and ground bars need to be separate in the sub panel, with the ground bar bonded to the box, and that you need to have separate neutral and ground wires running back to the main panel along with the 2 hots. That's where the confusion hits me, my main service panel does not have separate neutral and ground bars. So does that mean I can't add a sub panel since I can't separate the neutral and ground in the main panel? If that's the case, I'm thinking the best course of action would be to add a separate ground buss, bond it to the panel and move all of the existing equipment grounds to it from the neutral buss to free up the space I need?
Last edited: