how should you arrange breakers in a panel . I think that u have to like even the load . Do u put the 220 breakers up top then the single pole breakers on bottom?

Jason it makes no difference, run all the breakers down one side, both sides, start from the top, the bottom, what ever works good for you.

The only thing you do not want to do is skip every other space.

You should try to have as many breakers on phase A as Phase B.

Bob

I always start at the bottom. It makes adding after much easier as the ground and nuetral bars are easy to get at.

Just my 2 cents again but, I have seen where the bus bar was ruined when there were 2 large appliances on the same bus. For example a range was on the left side of a panel at took up spaces 1 and 3. Then on the right side in spaces 2 and 4 there was either an electric dryer or say a large central air conditioner that draws 40-50 amps. You would have a large load on those first top two bus bars. I have seen where the bus was warped, overheated and was damaged. You should check with the manufacture of the panel to see if there are any load restrictions. Some panels might say "no more than 80 or 90 amps. on any one bus bar".

That's why I like to put the large loads first and closest to the feed lugs or main breaker on the busses.

-Hal

I have seen bus damage due to loose spring contacts on the breakers, but never due to the arrangement of the breakers.
As inexpensive as CBs are we should never re-use old breakers. Someday, however, all our CBs will be AFCIs, and then, it may become more of a temptation to re-use an old breaker.

I go big breakers on top down to smaller ones. I don't think it makes much difference. It does make it look like the EC put some thouht into the panel instead of anywhere. It makes some breakers that are added after the fact stand out.

On some panels it makes sence to put the multi pole breakers on top becauce the mini breaker slots are only at the bottom. So latter adding a mini does not mean rearanging the panel and legand. I think that is the reason how it really got started putting the big breakers on top. I normaly use 40 space panels so that is not a factor.

Tom

I recently wired a small woodworking shop. Prices being what they are, it was cheapest to put in a 42 space panel for 10 or 15 circuits. I spread everything out in the panel by groups - 240 all together, main floor 120 outlets, loft 120 outlets, lights all have their own sections with a few spaces between them. Makes it real easy for the owner to find what he is lookng for. He wanted no hassles so I did a 100 amp service for a 16x20 shop. The inspector made a comment about how many outlets there were.

Big Jim, if you used a 42 circuit panel, obviously it had to be a 200 amp. panel. Did it have a main breaker? If so, were you not overloading the wire. If it was a main lug panel, did not the inspector question you on the amount of circuits you used for a 100 amp. service? Since the biggest 100 amp panel that I can get is 20 circuit, it seems that is all that is allowed for a 100 amp. service, to regulate how much of a load can be put on the panel. I am just asking just in case I am missing something here. Thanks for the reply. Steve

There is no limits on the number of CBs we can put on any one feeder. Twenty, fourty, eighty, it doesn't matter. What does matter is the computed load. If your computed load, using the rules found in the NEC, is less than 100 amps, then that 100 amp service or feeder is just fine with the 42 circuit, 200 ampere panel (with or without 200 amp main), if fed with a 100 amp feeder, and protected by a 100 amp main CB.
I have installed up to four, 42 circuit, 200 amp 3 phase 480 volt panels on a single 200 amp feeder, using double lugs on the first three panels. The panels were used for switching lighting, (SWD breakers) and were spaced throughout the building (a high school) at convenient locations in groups of two.
I was an apprentice at the time, and I questioned the combined loads of all those CBs. The journetman took the time to discuss the concept of loading, diversity of loads, and computed loads with me. It was a valuable lesson.
He also indicated that it did not matter where any circuit breaker was on the bus, but he preferred to have the higher ampacity ones closer to the main. It just felt better.

Sparkync, ITE makes a 30 circuit 100A MB panel, Square D makes a 32 circuit 100A MB panel. I have seen 42 circuit MLO panels with a 100A breaker installed with a retainer and used for a main. This is not a violation of NEC. Lighting and appliance panels are limited to 42 circuits by NEC. That's the only limit I am aware of.

An older FPE panel I have around suggests that DP breakers installed at the ends, SP breakers in the middle.

hi,
i have found that heavy consumers should be installed ahead of lighting loads on a bus. this will reduce the dimming effect on certain circuits when a dryer or oven kicks on..

this is not a big problem but i think it makes sense..


-regards

mustang

Sparky NYC, I just installed a Murray 30/40 circuit 100 amp main breaker panel. As for breaker layout I don't really think it matters.

Sparkync, CH makes a 30 circuit 100A MB panel, Sq D also makes a 32 circuit 100A MB panel. We have been using the CH 30 for all our 100 amp upgrade.

Thanks for the replies on my 100 amp question. I figured I might be missing something. I'll have to ask my supply house why they don't stock anything bigger than a 20 circuit 100 amp. panel. Thanks again... Steve

The panel is a in a stand-alone shop, no metallic connection to the associated house. 3 Wire arial feed. 100 amp breaker on the feed, 200 amp main included with the panel used as the disconnect. Overall system limited to 100 amp by the feeder breaker. Inspector never asked but I had load calcs and 100 amp was fine for the occupancy/usage.
It was actually a bit overengineered to minimize the effects of frequent motor starting loads. Once I crossed the breaker on the feeder, I could add almost any number of circuits as long as the total running load was low enough.

I always figured the big breakers at the top thing started because of the old style split bus panels. You always put the big guys up top because the bottom set of breakers was only fed from a 2 pole 50 at the top.

Funny you should say that, many resi panels have the rejection tabs for the first few breakers at the top, only allowing twins at the lower ones. Maybe a throw back to those type designs?

Do we have any pictures or other details about these panels anywhere on ECN?

Here in the U.K. it's been common practice for years to start with the largest breaker next to the main and then work down through the ratings, ending with the 5 or 6A lighting breakers at the far end. There's nothing to say it has to be done that way, but it's a very widely adopted convention.

I cannot imagine it mattering.

I like to group my breakers according to function (supanels, HVAC, appliances, lighting, recepts) and leave empty spaces between functions.

I like to split up the heavy loads to reduce heating of the breakers.

5 or 6 amp lighting breakers???????????

I need to visit the Non US portion of this site!

Pat - Remember, the mains voltage is double over there.

Yep! You can actually get 3A breakers from some manufacturers now, intended for feeding dedicated circuits for smoke/intruder alarm systems and such like.

You're most welcome.......

hi,
i also divide my panels...top half for ckts coming in from above..bottom half for ckts coming in from bottom..if possible

makes a neat installation..

i hate a messy termination job!

mustang

What size wire do you run for a 3-amp dedicated circuit? Is it thicker than a human hair?

Just about....

Actually 1 sq. mm is the smallest permitted size here, equivalent to about a #17 AWG.

Sorry I don't know of any pictures of a split-bus panel I mentioned above. Perhaps a quick description would suffice.

Take a main lug panel (no main breaker at the top) and cut the bus bars in half after the 12th breaker. This allows only 6 double pole breakers at the top of the panel, thus conforming to the "six disconnect rule" in the US. One of those double pole breakers then feeds the lower half of the panel where all the single pole lighting and appliance circuits are. Hope this helps.



[This message has been edited by Pat@Amber (edited 10-15-2004).]

There's a picture of one here:
https://www.electrical-contractor.net/ubb/Forum5/HTML/000718.html