With the awareness of arc flash, many giant manufacturers do not manufacture the Service Disconnect and the Automatic Transfer Switch located in the same section or enclosure. However, this practice can be seen in the field for switchboards rated as high as 600 Amps.
The dangerous part is the upstream of service disconnect is like a blind spot as the only protective device is the utility’s fuse on the primary side of the transformer and often result in high incident energy (greater than 40 Cal/cm2 in most of the cases) at the service disconnect. But because of service disconnect as protective device, in the downstream the incident energy on the ATS(normal-utility side) gets reduced to for instance less than 4 cal/cm2. The problem is although ATS has lower incident energy, it is located right below the Service Disconnect in the same section (enclosure). This is a arc flash hazard and I affix the conservative label (service disconnect) on the section that has service disconnect on the top and ATS at the bottom. So please share your thoughts on how you affix labels:
1. When the Service Disconnect & ATS is located in the same section (enclosure)
2. When there is a barrier between Service Disconnect and ATS located in the same section (enclosure).
According to the 2015 Edition of NFPA 70E 130.5(2), The arc flash risk assessment “…shall be reviewed periodically, at intervals not to exceed 5 years, to account for changes in the electrical distribution system that could affect the results of the arc flash risk assessment.”
According to 130.5(D) Equipment Labeling, the date is not listed as a requirement for including on the label. However, many believe the date is an important aspect of the label in order to keep track of the “5 years” time limit.
Here is this week’s question:
Do you feel the date should be included on the arc flash label?
In the NFPA 70E-2015 Handbook, page 122, 130.5(D) states incident energy or PPE category shall be on the equipment arc flash label, but not both. Yet when reviewing Annex H in the NFPA 70E-2015 handbook, on page 279 it states “Arcflash PPE categories may be applicable when using incident energy method to perform an arc flash risk assessment. When performing an incident energy analysis, the arc flash labels created may include an arc flash category”. Am I missing something or is this a mis-print?? READ MORE.
NFPA 70E requires that an Arc Flash Risk Assessment be updated when a major modification or renovation takes place. It shall be reviewed periodically, at intervals not to exceed 5 years, to account for changes in the electrical distribution system that could affect the results of the arc flash risk assessment. Countries outside of the US that do not use NFPA 70E may have a similar label review/updating requirement.
NFPA 70E further states that where the review of the arc flash hazard risk assessment identifies a change that renders the label inaccurate, the label shall be updated.
What is the maximum number of times you have updated any arc flash label since first applied?
-Still have original labels
-Updated more than twice
-No labels yet
-I don’t do labeling
It always seems as if we are kicking the dead horse on arc flash labels but I was just interested in your opinion of how to label a piece of equipment which is fed from a circuit breaker with an Arc Flash Reduction Switch (ARMS) or Reduced Energy Let-thru (RELT) switch.
We are currently performing a project with several new circuit breakers using the RELT switch.
Install two labels on the equipment? One with ARMS and one without?
To avoid confusion, how to distinguish between the two.
Wording on the label?
Any opinions welcome. READ MORE.