Mike Holt

Code Quandaries
What are the requirements for installing isolated ground receptacles?
Article 450: Transformers and Transformer Vaults 1
The operation of any facility depends on power distribution, which, in turn, depends on transformers. Safe and reliable operation of transformers is crucial
Code Q&A
Q. I was told that a back-fed breaker needs to be bolted into the panel. Is this correct?
Code Q&A
Q. Does the NEC require a connection of a parking lot lighting pole to a ground rod?
Code Quandaries
Q. What size THHN conductor is required for a 320A 3-phase feeder load for commercial office buildings?
Article 424: Fixed Electric Space Heating
Considering the fact that it has nine parts, at first glance, Art. 424 might seem like overkill for a device as simple as a heater. Walk into any hardware
Code Q&A
Q. Is GFCI protection required for drinking water fountains in office buildings?
Code Q&A
Q. A 400A service is made up of two 200A main breaker panelboards that are nippled together. Can the service conductors pass through one of the cabinets to supply the other panelboard?
Grounding and Bonding of Separately Derived Systems
Separately derived systems (SDSs) include most transformers as well as any generator or UPS supplying a transfer switch that opens the neutral conductor.
Code Q&A
Q. What are the NEC requirements for the installation of smoke detectors in dwelling units?
Code Q&A 1
Q. What are the Code requirements for bonding bushings on 277V or 480V branch and feeder and circuits?
Stumped by the Code?
Q. What are the rules on spacing receptacles in a dwelling unit?
Transformer Secondary Conductors 3
Similar to feeder taps, covered in the last issue, transformer secondary conductors can be every bit as confusing. Let's take a closer look at 240.21(C)
Code Q&A
Q. When PVC conduit is used, does the Code require an equipment grounding conductor between the meter enclosure and the service disconnect?
Code Q&A
Q. Section 110.14(C) requires the use of the 60°C column for 100A or less and the 75°C column for above 100A for conductor sizing. What is the value of THHN rated 90°C if the ampacity cannot be used for conductor sizing?
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