On this page 3 sections
Critical-load distribution: a designed subset that stays on — not the whole building, and not legally required emergency
Critical-load distribution is a designed subset: the circuits that have to survive an outage, fed from a transfer method that actually includes them. It is optional standby, not a hope at the main, and it is not the whole building on the generator.
Legally required instead
Egress, fire, and occupancy that the code names are emergency-power distribution.
The transfer method
The switch that moves that subset is an automatic transfer switch.
The set and the feeders
The building side of the generator is commercial generator electrical.
Critical-load distribution: the subset is sized to the generator and prioritized — not a wish list the generator cannot carry
A critical-load design is a calculation, not a checklist: the circuits that must survive are moved to a can the transfer method feeds, sized so the generator actually carries them, with a shed order if it cannot carry them all at once.
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Sized to the source
The subset load, its inrush, and the generator rating have to agree. A subset that starts everything at once can stall a set that could have carried it sequentially.
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A shed or priority scheme
When the wish list exceeds the source, load shedding or priority control decides what drops first — designed in, not discovered during the outage.
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Fed from the transfer
The can is fed downstream of the switch that actually includes it. A critical-load can wired ahead of the transfer stays dark exactly when it matters.
When critical-load distribution isn’t the right job
A designed optional subset is this job. Legally required emergency, or the generator connection, are not.
The occupancy named legally required emergency
That is emergency-power distribution.
Only the transfer switch is the problem
That is an automatic transfer switch.
Critical-load distribution questions
Can we put the whole building on the generator?
Not as a default. This job is a defined subset. Putting everything on is a different calculation, and it is still not legally required emergency.
The inspector asked for emergency power.
That is emergency-power distribution. Mixing optional standby with the legal set in one can is how inspections fail.
Is this a house critical-load panel?
No. This is commercial distribution: a can, a feeder, and a transfer method that actually includes the circuits. A house panel is a different product and a different page.
The ATS does not feed the can we care about.
Then the transfer method is the problem — an automatic transfer switch that sits upstream of this subset.
Still not sure it is the right job? Call (279) 972-9272 — available 24 hours.
Serving 19 communities across the Sacramento area
Litel Electric serves businesses throughout all 19 communities in our service area — from Davis and Woodland to Roseville, Folsom, and Elk Grove.
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We reply with what it involves and what has to be seen in person.
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Nothing is scheduled, and nothing is priced, until the equipment has been looked at.
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