Mike Holt

Articles by Mike Holt
Code Q&A
Q. I don’t see where 300.4 limits the number of NM cables through a given opening in wood or metal framing members. I don’t want to turn the framing members into Swiss cheese and reduce their structural integrity by boring a hole for every NM cable. So ...
Keep Your Cool When Working With A/C and Refrigeration Equipment 1
Demand for knowledge of Art. 440 requirements is heating up
Code Q&A
Q. Is GFCI protection required for a hard-wired spa? A. GFCI protection is required for both cord-and-plug and hard-wired spas containing single-phase equipment . GFCI protection isn't required for the outlet that supplies a spa that has integral GFCI ...
Clearing Up Multi-Family Dwelling Unit Calculations
Calculating multi-family dwelling unit service sizes needn’t be a difficult process, but it can be if you don’t follow the right steps
Code Quandaries
Stumped by the Code?
Code Calculations
When installing conductors of different sizes (or types of insulation) in a raceway, you can’t size the raceway based on Tables 1 through 12 in Annex C. You must instead follow this three-step process to determine the proper raceway and nipple size ...
Code Q&A
Q. Is it permissible to install line and load wiring in the same raceway? A. The NEC doesn't restrict the installation of line and load conductors within a common raceway. However, it does prohibit the installation of service conductors within raceway ...
Code Q&A
Q. On a 1,600A 277/480V service, is the neutral conductor from the utility transformer to the service disconnect considered a current carrying conductor if the only line-to-neutral loads is a 200A lighting panel supplying non-linear loads? A. The ...
Code Calculations
Art. 340 covers the use, installation, and construction specifications of service-entrance cable (Types SE and USE). Type SE cable has a flame-retardant, moisture-resistant covering. Type USE cable, identified for underground use, has a ...
Code Quandaries
Stumped by the Code?
Dwelling Unit Feeder/Service Conductor Calculations 2
How do you size conductors for residential services and feeders?
Code Calculations 1
The requirements for protecting the branch-circuit conductors, control apparatus, and circuits that supply hermetic refrigerant motor-compressors against short circuits and ground faults are noted in 440.22. The size and type of short-circuit and ...
Code Q&A
Q. Can a single transfer switch be used to supply both emergency and non-emergency loads, such as a UPS for telecom equipment? A. No, a single transfer switch is not permitted to serve emergency and non-emergency loads . However, a single generator is ...
Code Q&A
Q. Is a disconnecting means for an outdoor spa or hot tub at a single-family dwelling required to be located within sight of the unit? A. Per 680.12 and 680.42, a maintenance disconnecting means shall be installed within sight of spa and hot tub ...
A change to 338.10 of the 2002 NEC
A change to 338.10 of the 2002 NEC is meant to clarify that when Type SE service-entrance cable is used for interior wiring
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