OSHPD (CA) - Load Capacity Verification

[skeshesh]

I'm verifying load capcity for new load to be added to several distribution boards in a medical facility. OSHPD guidelines define level 1 & level 2 panels to be studied in this verification. One of the level 1 distribution boards, though, is fed directly from a 500kVA transformer using a 1600A, 3ph, 4w busduct. My intuition says to state the transformer size and available capcacity (1388A @ 208V) as a part of the load summary. The guidelines however do NOT call for any specific instructions in case a level 1 panel is not connected to another panel upstream but to a transformer. I'm don't like to make a habit of providing a bunch more information than necessary and muddying up the waters down the line somehow (although I guess I don't see how including this information can hurt). Any advice is much appreciated.

-Note: attached is the relevant policy intent notice. I know some on the forum who are experienced engineers/technicians, while not familiar with this document, may very well be able to provide great advice after reading it.

 

[skeshesh]

Note: apologies beforehand for bumping this thread but I posted it over the weekend and thought I may get some input during the weekend (in other words, I understand if moderators knock me down and lock me :roll

This issue is still unresolved for me. Not to say it's a technically perplexing issue, but sometimes it's hard to interpret the memos that get passed down. Your input is appreciated.

 

[shamsdebout]

Skeshesh,I would definitely include information about the transformer. When you add loads to you new panel they would need to see that total load on the system is not more than 500 KVA. Your new panel will be connected via a bus duct switch? What is the rating? What option will you be using for Level 1 or Level 2 verification since you have options?

 

[skeshesh]

Skeshesh,I would definitely include information about the transformer. When you add loads to you new panel they would need to see that total load on the system is not more than 500 KVA. Your new panel will be connected via a bus duct switch? What is the rating? What option will you be using for Level 1 or Level 2 verification since you have options?

I agree. The bus duct is properly rated (1600A, 3ph, 4w) as I stated in the original post. The OCPD ratings are proper as well, although I don't believe an OCPD at the secondary of the transformer is required in this type of setup. There's nothing against using a breaker at that point of course, but if I remember correctly the German standard prohibits it in their industrial practice, but I digress...
Most of the effected panels (level 1 & level 2) have been monitored over a 7 day period with an ammeter and I have the maximum demand data. Using maximum demand + maximum new load to be added (assuming a 1.25 multiplier for both) the new maximum connected load results in about 900A@208V,3ph which does not exceed available capacity. I was just a bit hesitant to include extra information in the report.

 

[shamsdebout]

I agree. The bus duct is properly rated (1600A, 3ph, 4w) as I stated in the original post. The OCPD ratings are proper as well, although I don't believe an OCPD at the secondary of the transformer is required in this type of setup. There's nothing against using a breaker at that point of course, but if I remember correctly the German standard prohibits it in their industrial practice, but I digress...
Most of the effected panels (level 1 & level 2) have been monitored over a 7 day period with an ammeter and I have the maximum demand data. Using maximum demand + maximum new load to be added (assuming a 1.25 multiplier for both) the new maximum connected load results in about 900A@208V,3ph which does not exceed available capacity. I was just a bit hesitant to include extra information in the report.

Cool, the measurements sound very good.