Frederic P. Hartwell

Frederic P.
Hartwell
Articles
Cord Wiring From Overhead
When dropping cord out of an overhead wireway or busway, the Code limits the amount of horizontal travel to a point of attachment. What if it isn't attached?With
The Middle Of The Wire Isn't Its End
The temperature restrictions in the Code for terminations have nothing to do with how you figure ampacities over the length of the circuit. Here's a contractor-focused
How Far Do Electrodes Extend?
Do grounding electrodes end at the building wall, or do they continue on into the building? How does that affect the application of other Code rules?Code
Hazardous Locations-Articles 500-505 (Part 2)
Choose the best answer:1. Assume qualified engineering staff and well-trained electrical maintenance personnel. How could they, as a practical matter,
Workspace Access For Large Equipment
If you design or install large equipment layouts, you need to watch out for special rules covering access to the required workspaces. Don't get confused
Using overcurrent protection for generator conductors 1
What does the NEC actually require in the way of overcurrent protection for conductors supplied by a generator?One of the more confusing areas of the
Transfer switches and the '96 NEC: what you need to know
New NEC changes allow for increased design flexibility in hospital essential electrical systems through the use of more transfer switches.Not all Code
Installing Class 2 and power cables in cable trays.
A Class 2 cable assembly can run on a wall with no separation from a power cable in most cases; can this be done in a cable tray?Cable trays are the only
Controller ratings for elevator motors.
Reduced starting currents don't justify derated controllers, but different motor time ratings may affect required horsepower ratings.An elevator service
Grounding separately derived systems to water pipes
The new paragraph in Sec. 250-80(a) creates questions about the relationship between water piping and separately derived system grounding.One of the most
Sizing continuously loaded conductors made simple.
Given a calculated load that is at least partially continuous, this updated four-part test assures that the conductors are correctly chosen.Selecting
Code applies to some internal wiring.
A control circuit that is part of industrial machinery, even machinery listed as a whole, must meet any applicable grounding requirements.We have received
Be aware of zone system equipment markings.
What do the new zone classification system markings mean, and how do they apply to specific equipment applications?Art.505 of the 1996 NEC introduces
Controller disconnects with obstructed access
Controllers need in-sight disconnects, but does that mean a glass wall could be between the disconnect and the controller?Can a glass wall, which provides
Unusual design issues involved in service change, part 2.
A small multifamily dwelling service change uses some innovative construction techniques, some of which could be used in industrial applications.In addition

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