How do i estimate or figure out the AIR rating for a panel?

[rhamblin]

Which IMO is good because then you can calculate the ACTUAL number. In another recent thread I complained about routinely getting unrealistic AFC values from the utility, often three times higher than the actual value (computed assuming infinite buss).

I went out back to look at the numbers on our 14,400 volt transformer and didn't see any impedence values or secondary available fault values. Is this normally stamped on the transformer somewhere?

 

[kwired]

I went out back to look at the numbers on our 14,400 volt transformer and didn't see any impedence values or secondary available fault values. Is this normally stamped on the transformer somewhere?

Impedance, yes, look harder it is probably there and you missed it.

Available fault values, no, actual value can depend on what the primary can deliver

 

[GoldDigger]

Look for %Z or similar, not a value in ohms.

Sent from my XT1585 using Tapatalk

 

[jim dungar]

I went out back to look at the numbers on our 14,400 volt transformer and didn't see any impedence values or secondary available fault values. Is this normally stamped on the transformer somewhere?

The information will be on the main nameplate. On a padmount transformer it is usually inside one of the compartments and not visible from the outside.

 

[Jraef]

Your utility's engineering dept should give you that information when asked. If it is a pad mount, they would have to open the cabinet to show it to you, which means sending out a lineman. They would rather deal with in via phone (or email) request.