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Electrical Wiring in the Home/Neutral to Ground(case) Bond Screw


Panel Instructions
Panel Instructions  

Ground bond Hole
Ground bond Hole  
Mr. Mossman,
I have an old Cutler Hammer service panel that needs a neutral to ground bonding screw installed.I think the panel is from the 6o's and the bond hole doesn't look like any modern panel.I've included 2 picture, 1 of the instructions and 1 of the ground hole.
My question is should there be a bar going from the ground screw to the lug on the neutral bar or is the screw enought? It sure seems that the screw would seat against the black plastic and not the metal. I haven't been able to find a picture of what this should look like for the old of panel.
Thank you,


If this is the Main panel in your home then the bonding screw should indeed be in there however
if this is a sub panel that is fed from your main panel the bonding screw should not be in there.

Having said that the location of the hole in the picture matches the location of the hole in the diagram so thats the spot. It appears that only part of the bonding screw "head" will come in contact with the "neutral bar" but if thats how they designed it then thats how it is. Most panel bonding screws are 8/32. The hole in the back of the panel may or may not be "tapped" (threaded). In that case you either have to get a self tapping 8/32 screw or use a "tap set" to do it. You may also have to cut the 8/32 down if its too long which will require a hand "crimper" that typically has the means to do that. Try to get an 8/32 with a slightly oversized head so it makes good contact with the neutral bar. You can test to see if the hole was tapped just by trying to screw an 8/32 in and see if it catches. Then you just have to cut it to fit. You can leave 1/4" extra that will easily recess into the wooden board behind the panel.

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"The Frank Williams School of Electrical Construction". My dear old boss is 100 ! and still going God Bless him. I started working for "Tenafly Electric" right out of high school at 19. He was tough but I learned more working for him in 8 and half years than most guys. We did mostly industrial work while doing some commercial and residential so I was fortunate to be exposed to all 3 areas of electrical construction. The guys I worked with were all good guys and I stay in touch with some of them still. Most of us went into our own buisness's which says something about the caliber of the guys I worked with. We had some interesting clients : Wella Corp. of shampoo fame, Farah Fawcett etc, I didn't buy shampoo for 10 years. It was a great place to work. Pan Am the former airline just before they went under, another great place to work, nice clean environment. C&C Metals, the largest button manufacturer in the US at that time, a not so clean environment but a very interesting place to work, lots of machine's cranking out buttons of all kinds but you had to be on your toes, it was a potentially dangerous place to be . All kinds of action going on around you.

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