Mike Dolt Enterprises
Mike Dolt Enterprises
User: scotteng, Location: Apollo Beach, FL
Asked on: Friday, April 17, 2009 at 4:56 pm EDT
Answered on: Sunday, May 12, 2024 at 4:59 pm EDT
Question: Does anyone know if or how to determine the fault current rating on a Zinsco Switchboard if nothing is listed on the equipment? Is there anyone or any company that maintains records of the original fault current listings for FPE, FA, Zinsco, etc.?Have a POCO replacing an XFMR and I need to "recertify" that the gear has an AIC to handle the new AFC when the utility does the XFMR replacement.I am familiar with the issues regarding Zinsco gear and their buss/breaker problems. Just searching for any knowledge base on fault current ratings for existing obsolete gear.
Determining Fault Current Rating of Zinsco Switchboard
Check the switchboard diagram or nameplate
Some older Zinsco switchboards may have a diagram or nameplate that lists the fault current rating.
Contact the manufacturer
Zinsco has been acquired by Siemens. You can contact Siemens to request information on the fault current rating of your switchboard.
Estimate the fault current
If you cannot find the fault current rating, you can estimate it using the following formula:Fault Current = Short Circuit Current / 0.707
Use industry standards
The National Electrical Code (NEC) and the Institute of Electrical and Electronics Engineers (IEEE) have guidelines for estimating fault current based on system voltage, substation size, and transformer capacity.
Companies That May Maintain Records
Zinsco Archive
Zinsco's archive is maintained by the Environmental and Healthcare Science and Technology (EHST) Practice Group of Cardno, Inc.
Siemens
As the successor to Zinsco, Siemens may have access to some records.
Local utilities
Some local utilities may have records of the fault current ratings of equipment installed in their area.
Recertification Process
Once you have determined the fault current rating of the switchboard, you can compare it to the anticipated fault current from the new transformer. If the switchboard's rating is insufficient, you will need to upgrade the equipment. You should work with a qualified electrician to ensure that the recertification process is carried out safely and in accordance with the NEC.
Caution: Zinsco switchboards are known to have potential safety hazards, so it is important to have them inspected and recertified by a qualified electrician.* Never rely solely on estimated fault current ratings. Always refer to the manufacturer's specifications or have the equipment tested to confirm the actual fault current rating. Flag for review