National Electrical Code Tips: Article 685 -- Integrated Electrical Systems
Many electricians work on integrated electrical systems without being aware of the fact and without applying Article 685. The same is true of electrical engineers whose area of responsibility includes such systems. Partly, this is because they are ill-defined. If you read the scope statement [685.1] you see a sort of definition which is rather long. Read our first five tips to get a more clear understanding of what an integrated electrical system is. You might be working on one now and not even know it! This is a super-short article once you get past the scope and information about which other articles apply; only three short sections..
- Article 685 does not cover unit equipment [685.1].
- Article 685 does cover integrated equipment required for orderly shutdown,
where such shutdown is required for safe operation [685.1]. An example would be
the reactor safety systems on the reactors of nuclear power plants.
- The NEC calls the equipment "integrated" because it exists as a unit [685.1].
A good clue as that something is integrated is that is has its own wiring
diagrams. As an example, the reactor safety system of a nuclear reactor has its
own associated drawings. They aren't mixed in with general lighting or other
systems in the building.
- The conditions of maintenance and supervision must ensure that only
qualified persons (trained and authorized) service this equipment [685.1].
- The system must have effective safeguards, and they must be properly
- Table 685.3 lists specific Sections from Chapters 2 and 4 as "Other
Articles" that apply.
- For UPS systems, Sections 645.10 and 645.11 apply.
- You must connect the output of an integrated electrical system power source
- Overcurrent devices can be accessible [685.10]. And they can be placed high
enough to be out of reach of unauthorized personnel. For example, you can
install them on a mezzanine or, alternatively, you can locate them high on a
wall such that a personnel lift is required to reach them.
- The two-wire DC circuits (if used) for these systems can be ungrounded
[685.12]. Control circuits can be ungrounded, if they are under 150V and
supplied by separately derived sources [685.14].