Upcoming NEC 110.24 changes

If you’re working a project that involves adding a new utility service, your project may become infected (affected /grin) by NEC 110.24.

Back in 2011, the NFPA code committee added section 110.24 to the National Electrical Code. Snips of how the code has developed further below. The 2011 code panel developed the rule stating that for service equipment other than residential needs to be field marked with the calculated available fault current. By 2017, the code requires that the calculation be documented and made available. As more people shift to the newer codes, there will be more questions and interpretations. For example:

–          What are the documentation requirements for compliance?

–          During the design, the engineer may not know the parameters of the transformer the utility is to provide. Does the electrician come back to the engineer?

–          Can the electrical contractor provide the data? Some websites have nifty excel files.

For future work, it is safe to assume that at engineers will start getting more involved in project completion. The current horizon contains labeling and project documentation requirements. The future may require so much more…


2011 NEC:

2014 NEC added the following informational note to section A.

Current 2017 NEC version as follows: