two residential panels, one for 120, one for 240 v circuits ?

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Stevenfyeager

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United States, Indiana
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electrical contractor
I've seen houses with two panels, one dedicated to two pole breaker circuits and the other panel for 120 v circuits. And some of you have posted you like doing that. What are the advantages ? I will have two 200 amp panels. (actually, here it is a total 320 amps but called '400 amps' service ) Thank you.
 
Stevenfyeager said:
I've seen houses with two panels, one dedicated to two pole breaker circuits and the other panel for 120 v circuits. And some of you have posted you like doing that. What are the advantages ? I will have two 200 amp panels. (actually, here it is a total 320 amps but called '400 amps' service ) Thank you.
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In general on a 400 A service you are going to have sub panels. Those are going to be fed by some fairly large breakers. So you can use a more expensive 400 A main panel and cheaper sub panels. Keeping the larger loads grouped together means lower voltage drop and less surge impedance. But it’s more conceptual than anything. Depending on the layout of the loads it might make sense to physically distribute the subs. For instance locating a sub near the kitchen, pool house, or garage areas, especially with the potential need for car chargers, central vacs, or other large loads.
 
Stevenfyeager said:
I've seen houses with two panels, one dedicated to two pole breaker circuits and the other panel for 120 v circuits. And some of you have posted you like doing that. What are the advantages ? I will have two 200 amp panels. (actually, here it is a total 320 amps but called '400 amps' service ) Thank you.
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IMO there is no advantage to installing the two panels as described.
 
IMHO They're are no advantages to doing that... Now years ago , which in Indiana it probably still applies. They had a service panel or equipment panel . I think it was 408 something. At that time you could not install a single pole or branch circuit breaker in an equipment panel . such as a six 2 pole breaker panel no main.
 
Here it used to be that the power company gave a better rate for appliances if the house was all electric.

So we would put in 2 meters and 2 panels
1 for 120v use and 1 for 240v use.

I've seen guys who like to do that even now, for no reason other than it used to be done that way.

If I have a 400 amp service, I'm generally looking to have a panel in each half of the house so home runs don't go as far, and I put 120 and 240 loads in each
 
Thank you. Are there any suggestions in keeping lights dimming when the AC kicks on ? Sometimes I see that. My instructor (as I posted some years ago) recommended putting heavy loads near the top, closest to the main. I've tried that, not sure it helps.
 
One reason would be a generator panel. A 400A or 200A transfer panel costs more than a 100A one. You could put the transfer switch in front of the 120V panel, especially if the generator can't handle any of the large 240V loads. One large panel is better though if you are smart enough to know what to manually load shed.

I dont see voltage drop or flicker as an issue. The voltage drop on the bus is almost nothing. In service entrance conductors almost nothing. Voltage drop can be significant on the weenie wires the poco uses to serve you. But splitting panels is past that.
 
Stevenfyeager said:
Thank you. Are there any suggestions in keeping lights dimming when the AC kicks on ? Sometimes I see that. My instructor (as I posted some years ago) recommended putting heavy loads near the top, closest to the main. I've tried that, not sure it helps.
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It doesn't really help. 🤫
 
Stevenfyeager said:
recommended putting heavy loads near the top, closest to the main. I've tried that, not sure it helps.
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Doesn't matter. The whole bus is rated the same top to bottom.

I have a few things I consider:
1) I like to group all my 15s together and all my 20s together. That way if somebody is turning off all of the 15s or 20s it's easier to inow you got them all. Typically 15s on one side and 20s on the other, but not necessarily

2) 2-pole breakers typically go in so as to have both sides fairly evenly filled. But it's not hard and fast.

3) if I can, wires coming from the left go in the left side, and wires coming from the right go in the right side.

t's not usually possible to get all 3 of those, so I just go with best case compromise.
 
suemarkp said:
One reason would be a generator panel. A 400A or 200A transfer panel costs more than a 100A one. You could put the transfer switch in front of the 120V panel, especially if the generator can't handle any of the large 240V loads. One large panel is better though if you are smart enough to know what to manually load shed.

I dont see voltage drop or flicker as an issue. The voltage drop on the bus is almost nothing. In service entrance conductors almost nothing. Voltage drop can be significant on the weenie wires the poco uses to serve you. But splitting panels is past that.
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Look at soft starting options in the HVAC. Your eye is very sensitive to light flicker.,,
 
Only time I have seen something like that is when a building is supplied with 120/240V 3Ø, and most of the single phase circuits are supplied in a adjacent 1Ø panel, but few homes in the US have 3 phase.
 
I prefer stacking 2-poles on one side and 1-poles on the other. The knockouts tend to work out that way, too.

Here, they're separated by genny and normal loads:
 

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One thing I would advise (and probably known to many) is careful placement of breakers serving heavy, long-running (not necessarily "continuous") loads. I've seen several 2p 50 or 60A breakers feeding central heat that were across from or sandwiched between other breakers for the water heater or outside unit, etc. overheat and melt the breaker's shell--sometimes without tripping. I try to keep heavy, long loads away from each other and from sharing bus tabs.
 
Relevant to @Electromatic 's point is to remember the 'bus stab limits' that many panels have.

You are only permitted so many amps worth of breaker connected to each finger on the bus. Given that breakers on opposite sides of the panel often share stabs, as do tandems, this is an easy limit to exceed if you have many large loads

Jon
 
winnie said:
Relevant to @Electromatic 's point is to remember the 'bus stab limits' that many panels have.

You are only permitted so many amps worth of breaker connected to each finger on the bus. Given that breakers on opposite sides of the panel often share stabs, as do tandems, this is an easy limit to exceed if you have many large loads

Jon
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That is the actual load correct not the breaker size?
 
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