400 amp disconnect

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Advanced Electric Inc

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WV
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Electrical contractor
Can anyone enlighten me on a disconnect issue? I have a 400 amp duel lug ATS outside and two 200 amp panels inside both are MLO. 1 panel is about 40 feet inside and the other is about 70 feet. Is it legal to duel tap these on a 400 amp without a 200 amp DC? ATS is service rated of course.
 
So you are running 70 feet with say 4/0 and have it on a 400 amp breaker? I think not.. btw welcome to the forum
 
The ATS is the service disconnect? Assuming that your 200 amp panels are fed by taps and the tap rules apply. The 200 amp panels require a single main OCPD or upstream protection.
 
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You could change the MLO panels to MB, but at that distance, I do not believe you could use the tap rule. You will have to put two 200 amp disconnects near the tswitch.
 
hillbilly1 said:
You could change the MLO panels to MB, but at that distance, I do not believe you could use the tap rule. You will have to put two 200 amp disconnects near the tswitch.
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I agree, the tap conductors would need to be routed on the outside of the building to use a main in the panels.
 
Probably the original service had two 200 amp breakers that fed the MLO, but are being replaced with the 400 amp service rated transferswitch? I would assume the OP is not feeding the 400 with the two 200’s? But then you know what you get when you assume.......
 
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