I am adding a 50 amp sub panel to my shed. I am using thwn 6 awg wire in pvc conduit 2 hots 1 neutral 1 ground. I have installed a ground rod to sub in shed also. Here are the questions I have conduit that leads straight to a sub panel next to main. Can I feed 50 amp sub off a 60 amp sub? Also the 60 amp sub next to main only has 2 hots and a neutral no ground wire it is bonded do I need to bring new sub in shed to main? Also shouldn't my 60 amp sub have a ground to main? I hope I did not confuse anyone. existing panel !enter image description hereenter image description here

  • Can you post photos of the inside of the existing subpanel? – ThreePhaseEel May 30 '20 at 22:55
  • This is a pic of existing sub. – Kevin May 30 '20 at 23:25
  • What circuits/appliances does the existing subpanel feed? How large is the shed, and are there any unusual loads in it, or merely lights and general receptacles? – ThreePhaseEel May 30 '20 at 23:36
  • Shed is 12 by 16 only general outlets and lighta and a 2 hp pool pump. I may use some small power tools. Circular saw etc. The existing panel is only general outlets and lights. It did run baaeboard heating but that is ripped out now. – Kevin May 30 '20 at 23:49
  • It alao runs a air conditioning for house – Kevin May 31 '20 at 0:17

ThreePhaseEel is investigating some important aspects, but here's one that I notice.

Your 6 AWG wire, if it's copper, it's good for 65A officially but you can breaker it at 70A. Which is kind of interesting because your subpanel 1 is already 60A and presumably has a 60A breaker in the main panel. What does this mean?

Well, since subpanel 1 is already breakered at 60A, that means you do not need an additional breaker to protect the #6 Cu wiring onward to subpanel 2. You can use thru lugs, subfeed lugs, or simply use 3-void Polaris connectors to split the feeder between subpanel 1 and subpanel 2.

The only way this fails to work is if subpanel 2 a) does not have a main breaker (uh-oh!) and b) has internal busing that can only take 50A. But it would be crazy to use such a small subpanel. I would implore you to return it and get a bigger one. Spaces are dirt cheap, and running out of spaces is painful. Even a modest 6-space panel will have at least 60A and probably 100A busing.

  • Thank you .in shed is a 125 amp panel lots of space which i can convert to main. What about the ground its bonded in existing sub panel? – Kevin May 31 '20 at 1:52
  • @Kevin I would buy accessory ground bars for that panel, and then retrofit a ground between sub #1 and the main. Retrofitting grounds was partially legal but is now universally legal as of NEC 2014. – Harper - Reinstate Monica May 31 '20 at 2:55

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