code compliant install

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shockerz

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came across this installation: coming from a 2100 cb to feed a 200 amp service rated cb transfer switch and then to a panel with 2 -260 cbs for 2 subpanels? generator is 20 kw.i have a customer who wants me to install a 200 amp cb service rated transfer switch and generator on a 100 amp service for future service up grade. can i install a 2100 cb disconnect first and then wire to the 200 amp transfer switch with the thinking that the 2100 will protect the service conductors? i hope i amp clear on my explaination, thank you harry
 
It makes little difference what size transfer switch you install as long as it is rated at least as large as the conductors and supply overcurrent device. A 200 amp or 400 amp switch can be installed and fed by a 100 amp breaker as long as the conductors are rated 100 amps.
Not much different from using a 30 amp rated switch on a 15 amp circuit.

However, since you mentioned Code compliant. If it's an automatic transfer switch, you might note 702.5. The generator must be sized to handle the load being transferred,
 
shockerz said:
came across this installation: coming from a 2100 cb to feed a 200 amp service rated cb transfer switch and then to a panel with 2 -260 cbs for 2 subpanels? generator is 20 kw.i have a customer who wants me to install a 200 amp cb service rated transfer switch and generator on a 100 amp service for future service up grade. can i install a 2100 cb disconnect first and then wire to the 200 amp transfer switch with the thinking that the 2100 will protect the service conductors? i hope i amp clear on my explaination, thank you harry
Click to expand...

2100 cb as in 2 pole 100 amp breaker?
 
gen load

gen load

i have seen a few 20 kw / 80 amp generators suupplying full 200 amp services with no load shedding. because they come with a 200 amp switch. also
augie47 said:
It makes little difference what size transfer switch you install as long as it is rated at least as large as the conductors and supply overcurrent device. A 200 amp or 400 amp switch can be installed and fed by a 100 amp breaker as long as the conductors are rated 100 amps.
Not much different from using a 30 amp rated switch on a 15 amp circuit.

However, since you mentioned Code compliant. If it's an automatic transfer switch, you might note 702.5. The generator must be sized to handle the load being transferred,
Click to expand...
 
shockerz said:
came across this installation: coming from a 2100 cb to feed a 200 amp service rated cb transfer switch and then to a panel with 2 -260 cbs for 2 subpanels? generator is 20 kw.i have a customer who wants me to install a 200 amp cb service rated transfer switch and generator on a 100 amp service for future service up grade. can i install a 2100 cb disconnect first and then wire to the 200 amp transfer switch with the thinking that the 2100 will protect the service conductors? i hope i amp clear on my explaination, thank you harry
Click to expand...

If I understand what you are saying, yes, as long as that 100 amp disconnect is rated for use as service equipment you would be fine.
 
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