Electrical Study

[hawkeye23]

When doing a electrical safety study as in 70e should the engineer doing this require the customer to have the main electrical switchgear and motor control centers to be in good condition as in recently pm 'ed ? Should they require an inspection first or look over before getting into a contract ? I am sure negelected systems will have differrent outcomes from well a maintained system .
If someone has any information about this type of work I like to say thanks for your time in advance.

 

[zog]

Yes, the requirements for this are in article 200 and 205 of the NFPA 70E.

The dirty little secret about arc flash is the study and resulting PPE requirements are all based on the big assumption that the OCPD's will operate in the times the OEM TCC's indicate. If you don't test, you don't know if they will.

A 2007 IEEE paper addressing the reliability and integrity of low voltage overcurrent protective devices [8] reviewed various surveys. It was found that nearly one‐third of all circuit breakers failed while in service and thus would not have been identified unless proper maintenance was performed. In addition, 16% of all circuit breakers failed or were damaged while opening.

Even the normal testing methods are not accurate either when it comes to percise opening times, in order to test a breaker you have to open it, rack it out, and test it. The act of opening it breaks loose hardened grease, excersises springs, etc...So when it is tested it does not represent a true opening time for a breaker that has been sitting closed in a cubicle for years. The only true indicator of in use clearing times is to test using "first trip" methods (Vibration analysis).

 

[GBShade684]

Yes, the requirements for this are in article 200 and 205 of the NFPA 70E.

The dirty little secret about arc flash is the study and resulting PPE requirements are all based on the big assumption that the OCPD's will operate in the times the OEM TCC's indicate. If you don't test, you don't know if they will.

A 2007 IEEE paper addressing the reliability and integrity of low voltage overcurrent protective devices [8] reviewed various surveys. It was found that nearly one‐third of all circuit breakers failed while in service and thus would not have been identified unless proper maintenance was performed. In addition, 16% of all circuit breakers failed or were damaged while opening.

Even the normal testing methods are not accurate either when it comes to percise opening times, in order to test a breaker you have to open it, rack it out, and test it. The act of opening it breaks loose hardened grease, excersises springs, etc...So when it is tested it does not represent a true opening time for a breaker that has been sitting closed in a cubicle for years. The only true indicator of in use clearing times is to test using "first trip" methods (Vibration analysis).

What about fuses?

 

[GBShade684]

Article discussing topic...
http://www.cooperindustries.com/con...n-3002-spd-ocpd-servicing-and-maintenance.pdf