Did this install today on my home. How'd I do?
I asked an old electrician and he said that I ought not to mix the Neutral with the Ground at the main like that cause "it could cause problems", though he did not give further detail. But if the Neutral and Ground Bus are bonded in the main anyway (which they definitely are on this panel), what does that matter? I used the ground bus for the #6AWG Neutral (white wire) because the other buses did not have any opening's big enough for the #6, at least it didn't look like it would fit…
I used #6AWG THHN for all 3 conductors and #10AWG THHN green for the ground, and these are are conveyed in the Steel Flex 3/4" you can see coming in from underneath. I installed bushings in the FMC where they connect to the compression fittings. The Sub panel Neutral is Isolated. This is fed from a 50 Amp (Connecticut Electric UBITBA250 Challenger “A” Series Circuit Breaker, 2-Pole 50-Amp) housed in the main. Which used to house a 30 amp for an old electric dryer circuit no longer in use. I had to source breakers for this old Challenger panel and they were pricey.
It's mounted to a 3/4" plywood board that is then fastened to the studs. The main is a 100 AMP service and according to the usage calculations for the house I'm well within that. Most big appliances are gas. I needed more outlets in the garage for my dust collector and table saw.
I live in San Francisco. The Panels are located in the garage at street level. Plan is to run 1/2" emt to job boxes along the workbench top, protected with GFCI outlets. I may at a later time install a 220 for the dust collector and a welder, which is why I went 50 amp.
So am I gonna burn the place down?
Best Answer
OK the NEC and AHJ have always allowed the grounding conductors (Ground) and the grounded conductor (Neutral) to be connected to the neutral bus bar in the main panelboard or loadcenter. You are correct the busses are interlocked and bonded. The only reason some electricians put the ground on one side and the neutral on the other is because of the "workmanlike manner" clause. I have never seen where mixing them has ever caused any problems.
Now, your sub panel is not covered under this rule due to the single point of ground rule. You need to install a grounding bus and an isolated neutral bus. Each bus must be connected from the service panel with a corresponding conductor and you do not bond the sub panel neutral. This is true with any other device, equipment or sub panel installed downstream of the service panel.