I’m Australian, but some of the older switchboards in industrial installations are similar in appearance to the top image.
The middle would have a busbar (or three if it’s a three phase panel) that connects the circuit breakers to the main switch. The cables are connected to the far left and far right sides of the breakers.
It could be different in the US, though, if anyone with more relevant experience wants to chime in.
Edit: looking back at the top image, I’m reminded that the US uses split phase in some places, so that top panel likely has two busbars down the middle.
Varies with installation type, age, and scale, but one common approach is to daisy chain the breakers via rails that carry each phase. I couldn’t find a good picture, but basically the rails and breakers are standardized so that a row of breakers will line up with the-rail terminals, so when you connect the rail to the mains you’re good to go. On the output of the breaker it’s common to use cable ducts to keep everything nice and tidy.
Every building receives 240V and splits it into a pair of 120V phases. Three phase power is basically only installed at large industrial sites or very specialized shops.
here if you need anything over certain power (6kW; depends on country i guess) you need a three phase installation, and even if you get single phase, it’s really handled as three phase split between single phase customers (a block gets three phase supply, then splits flats in three groups, each group gets connected to one phase). this gets supplied by a distribution transformer that might serve somewhere around 200 people per (in residential areas)
i understand that sometimes americans also get distribution like this, with 208/120 three phase coming from substation, without 240v available
wait, how do you route cables in there? is there just a massive bundle right through the middle?
I’m Australian, but some of the older switchboards in industrial installations are similar in appearance to the top image.
The middle would have a busbar (or three if it’s a three phase panel) that connects the circuit breakers to the main switch. The cables are connected to the far left and far right sides of the breakers.
It could be different in the US, though, if anyone with more relevant experience wants to chime in.
Edit: looking back at the top image, I’m reminded that the US uses split phase in some places, so that top panel likely has two busbars down the middle.
Varies with installation type, age, and scale, but one common approach is to daisy chain the breakers via rails that carry each phase. I couldn’t find a good picture, but basically the rails and breakers are standardized so that a row of breakers will line up with the-rail terminals, so when you connect the rail to the mains you’re good to go. On the output of the breaker it’s common to use cable ducts to keep everything nice and tidy.
EDIT: Found a picture:
american version would probably only have two phases at best, and possibly just one
Every building receives 240V and splits it into a pair of 120V phases. Three phase power is basically only installed at large industrial sites or very specialized shops.
here if you need anything over certain power (6kW; depends on country i guess) you need a three phase installation, and even if you get single phase, it’s really handled as three phase split between single phase customers (a block gets three phase supply, then splits flats in three groups, each group gets connected to one phase). this gets supplied by a distribution transformer that might serve somewhere around 200 people per (in residential areas)
i understand that sometimes americans also get distribution like this, with 208/120 three phase coming from substation, without 240v available