Electrical panel : Ground/Neutral bus bar question

I would never replace copper with aluminum. Aluminum is less conductive and tends to expand/shrink as it heats/cools from current. My previous home had aluminum wiring and it was a pain in the a$$.

May be, it wasn't clear but I am trying to replace Aluminum Ground/Neutral bar with Copper and I am finding hard to match mounting holes etc. My question is, can I buy ILSCO N174 ( or alike) and drill hole ( at wire hole) to match with mounting position at panel ? Is it worth the effort ? The main bus on my panel is Silver plated Copper.

Thanks

Diwakarv,

How will you electrically/mechanically connect the copper neutral/ground bar to the existing AL, aluminum, bus that feeds the panel from the meter socket? If the AL bus is not made of high strength 6061-T6 aluminum alloy you cannot mechanically bolt the copper neutral/ground bar directly to the AL bus. Even if you were to use an anti-oxidation paste between the two metals, given time the copper will burn itself free from the AL bus.

As for the neutral/ground bars in the CH panel they are not made of regular AL. If they were you could not terminate copper wire to them. They are made from 6061-T6 aluminum alloy and are dual rated for use with copper and aluminum conductors. More than likely they are also electro-tin plated.

Food for thought, the CH 200 amp main breaker in the panel has mechanical lugs made of 6061-T6 aluminum alloy.

Here are a couple of manufacture examples.

Link

Link

I would not mess with the factory installed neutral/ground bar found in the CH Load Center electrical panel. First it will void the UL/CSA assembly listing as well as the manufacture warranty.

If for some reason the electrical connection of your copper neutral/ground bar to the AL bus that is fed from the source utility transformer was broken, became open, the unbalanced 120V load from L1 to source neutral and 120V load from L2 to source neutral could not return to the source on the service neutral. The unbalanced load would then become part of the L1 to L2 series balanced load circuit. That's not good!

Here are a couple of nice videos on the subject.

Link
For this one it would have been nice if the guy would have first used two 120V bulbs of the same wattage. Then when he broke the main neutral connection, thus putting the two bulbs in series with one another, he could have measured the voltage across each lamp and showed the voltage across each bulb around 120V.

After the above example I would of then liked him to change out one of the bulbs to the higher wattage bulb. Then measure the voltage across each lamp again. With this example he would have measured a lower than the normal 120V across the higher wattage lamp load, and a higher than normal 120V across the lower wattage lamp load.

In this video the guy does a little better job.
Link

Thing to remember, only the unbalanced load returns on the main service neutral back to the source. The balanced 120V loads of L1 to neutral and 120V loads of L2 to neutral are in series with one another. It the nature of how a split phase secondary winding of a transformer works.
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Jim

Hi Jim,
It is always educational to read your response. I takes me an hour to read/understand your post and additional couple of hours to reply :-) I surely appreciate your feedback.

CH panel CMBE4242B200BTS uses part no. N-8108-86 , catalog no. NBAE-0924-2 , which tin plated aluminum (6061-T6) for ground/neutral bar.
http://www.ilsco.com/documents/PDF/TechnicalDrawing/N8108.pdf.
I still don't know the whether the bus is AL or 6061-T6.

"Food for thought, the CH 200 amp main breaker in the panel has mechanical lugs made of 6061-T6 aluminum alloy"

I didn't know that, thanks for info.

It seems , my goal of having a all copper panel is unrealistic. Every panel ( including QO) uses 6061-T6 extensively, this alloy is 43-45% conductive compared to copper.

8 (qty) 30 amp breakers feeding 8 (qty) dedicated receptacles. ($80,00)
One 30 amp single pole sub-panel breaker for each metal box duplex receptacle. See 125 amp 2-pole description for more info.

Does not meet NEC code or local AHJ. I bet Krell said it was OK though.

Per NEC Code the maximum breaker size for 2 or more NEMA 5-15R 15 amp rated receptacles is 20 amp.

For a NEMA 5-20R 20 amp rated receptacle the breaker shall be 20 amp, period!

Thanks Cdrc. I am using copper SE cable & 4 AWG solid copper GND wire terminated to 8 feet solid copper bar ( about 50 feet from Main panel) and to water mains. I have bought Cardas in wall AC for two dedicated circuit, 10/2 romex for subwoofer, 10/2 as spare. My outlet are Oyaide R1 with wallplate. Lugs in my meter are copper, not aluminum ( special order from Flexcenter).

I am sort of disappointed that I couldn't get all copper panel anyways , knowing that AL is just 40% conductive to copper.

I wish I could post picture on Audiogon to expain my situation further. Lug for GND ( where 4 AWG attaches in the panel) can accept copper and AL ( it is 6061-T6) and GND strap which connects to GND/NEUTRAL bus bar (BSSUSE Bonding Strap) is also 6061-T6. Ideally, I should be able to replace GND/neutral bus with N174 copper bar.

Again since bonding strap is also 6061-T6 ( Tin plated), copper bar screw to it, should not cause any harm. I am bit skeptical/reluctant after Jea48 comments.

Here is picture of the panel that I discussing about
https://www.flickr.com/photos/131393447@N08/17442124326/in/shares-S47X7U/

In my opinion ( as an circuit engineer), if the resistance is introduced in source path ( breaker contact, OR main distribution bus) or return path ( to GND via Ground/Neutral AL bus), it is bad. It is definitely worse in return path since all the current from refrigerator/washer/dryer/oven and all electrical appliances are dumped into this. Having this path as AL instead of CU is not the best.
Sure, according to NEC perspective, it is enough to carry current ( whatever rating it is designed for ) but it is definitely not desirable from audio application.

This is response that I got from eaton

My question

Hi,

Can I replace neutral/Ground (Tin plated aluminum) in
CMBE4242B200BTS panel with ILSCO copper bars ?

Thanks

Reply from Eaton

Since it’s a service entrance panel, the neutral/ground is bonded, so I don’t see any issue with changing to a different ground bar. However if any inspector noticed the difference and called you out on it, we don’t have anything official documentation to back you up in doing this. So I would suggest you hold onto the original neutral/ground in case the inspector says you can’t change it.

Since it’s a service entrance panel, the neutral/ground is bonded, so I don’t see any issue with changing to a different ground bar.

Do you understand what the guy means when he says the neutral/ground bar is bonded? What that means, and yes that is the case with the meter/Load Center combo unit you bought. The service neutral conductor is bonded, connected, to the meter socket steel enclosure. Inside the Load Center electrical panel the neutral/ground bar is bonded, connected, to the steel metal enclosure again. Yes that is the way it is done. Even where the meter socket is separate from the electrical panel it is Bonded in the same way. (At the meter socket and again at the electrical panel.)

So can / does the unbalanced load current travel on the steel enclosure between the two bonded points as well as the AL bus between the meter socket main service bonded neutral connection and the bonded neutral bar connection? You bet.

What you should have asked the guy, is the AL bus that connects the main service neutral conductor in the meter socket to the neutral/ground bars in the electrical panel made of 6061-T6 AL alloy? That is what you need to bolt a copper neutral/Grd bar to the AL bus. If the AL bus is not 6061-T6 AL alloy and you connect the AL bus to copper the connection in time will fail. Will the bonding screws/straps/steel enclosure carry the unbalanced load current back to the utility transformer? ya, I guess.... Will the bonding screws connections to the main service neutral conductor keep the L1 to neutral and L2 to neutral 120V nominal voltage stable? Hopefully.... Will the total resistance of the bonding screws and steel enclosure be less than the AL bus that connects the main service neutral conductor to the 6061-T6 AL alloy neutral/Grd bars? I doubt it...
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