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As many as you wish, as long as you do cross 200 amp limit
NOBODY!
I am assuming by your description that the panel is protected by a 90 amp breaker and the breakers in the panel when added up is 200. This is okay as long as your 90 amp breaker trips on a regular basis. It is typical for the breakers to add up to more than the main breaker under the assumption that you would rarely be running each circuit at its maximum capacity.
simply four but also aplying diversity they may be increased depending on situation
When I went to a 100 amp service I could not find a 100 amp. breaker in stock. I used a 60 amp. breaker and have never blown it. The 200 amp you are using can handle up to 200 amps, but if you use a smaller breaker it will only handle up to that amperage. The 200 amp is usally the total amperage of all the breakers comming out of the box. You will probably never come anywhere near using 200 amps at one time.
As many as you wish, as long as you do cross 200 amp limit
This would typically be seen in older residential installations where the service was of such a high amperage that the mains required larger breakers than were available (for that panel). Placing two breakers in parallel allowing sharing of the load. Two breakers per (split) phase would total four breakers. Two breakers of 50 amp rating each (in parallel) provide (generally) 100 amps of protection. Two sets of two would provide mains protection for a 200 amp service.
Check the nameplate on the service panel. There it will tell you what the buss capacity is. On a 200 amp service nothing in the wiring configuration is allowed to be less than that the service rating. In the market there are 200 amp 42 circuit distribution panels.
NOBODY!
I am assuming by your description that the panel is protected by a 90 amp breaker and the breakers in the panel when added up is 200. This is okay as long as your 90 amp breaker trips on a regular basis. It is typical for the breakers to add up to more than the main breaker under the assumption that you would rarely be running each circuit at its maximum capacity.
#10 wire is used on a 30 amp service.
simply four but also aplying diversity they may be increased depending on situation
When I went to a 100 amp service I could not find a 100 amp. breaker in stock. I used a 60 amp. breaker and have never blown it. The 200 amp you are using can handle up to 200 amps, but if you use a smaller breaker it will only handle up to that amperage. The 200 amp is usally the total amperage of all the breakers comming out of the box. You will probably never come anywhere near using 200 amps at one time.
Sizing what goes into a 200 amp panel whether it be split breakers or normal size breakers is based on the amperage values expected under normal use of the devices connected to the panel. For example if you could look at a continuous curve of usage you would see it vary throughout the day. This is because under normal living conditions you use you lights and appliances at different time. If you started to trip the main 200 amp breaker and the other breakers weren't tripping then you would need to increase your service from power company and add a new main panel. So giving you a count isn't possible. You could call in an electrician to measure your usage or just add the breakers you need and see if the main breaker trips.
A #6 copper conductor is used to bond a 200 amp distribution.
No. If device draws 200 amps breaker will trip.
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