Three questions

Nov. 1, 2000
Q I have three questions regarding an industrial chemical manufacturing plant.1. Our laboratory can't use surge suppressor strips for the lab equipment. The inspector said, "The minute you mounted those strips on the wall it was a violation." I have been asked to install 50 duplex receptacles. We already have these circuits GFCI-protected by breakers. The wall outlet has an electrical strip plugged

Q I have three questions regarding an industrial chemical manufacturing plant.

1. Our laboratory can't use surge suppressor strips for the lab equipment. The inspector said, "The minute you mounted those strips on the wall it was a violation." I have been asked to install 50 duplex receptacles. We already have these circuits GFCI-protected by breakers. The wall outlet has an electrical strip plugged into it where various lab equipment is then used. We bought the strips as industrial grade, with individual breakers and with mounting tabs.

2. The second question concerns our warehouse. "That disconnect switch doesn't have the 3-ft clearance required," we've been told. This disconnect is for an air compressor air dryer. It's located on a wall behind a product header that is 2 ft away. There is no routine maintenance done on this disconnect. The breaker that feeds the disconnect can be used to LOTO the equipment when needed.

3. My third question concerns a trash compactor. The inspector said it is a Code violation to use flexible SO cord for a permanent installation. The SO cord has a watertight connector at the wall disconnect switch. It feeds to the machine and then enters the compactor's control box.

A 1.The "suppressor strip" is most likely listed as either a "Transient Voltage Surge Suppressor," or a "Relocatable Power Tap." Either way, these devices are commonly provided with a mounting means. Simply mounting them to a wall does not necessarily violate their listing. As long as they are applied in accordance with their instructions and listing, the NEC has no special rules about them at this time. Incidentally, the UL "White Book" says relocatable power strips "are intended for indoor use as relocatable multiple outlet extensions of a branch circuit to supply laboratory equipment, a home workshop, home movie lighting control or musical instrumentation." Your application appears to lie within the intended use of the device.

2. The disconnect is required to have workspace in front of it. The piping appears to interfere with the workspace requirement. These rules are found in Section 110-26. The dedicated workspace must be at least 36-in. deep, 30-in. wide and 78-in. high. Although you may argue that there is no routine maintenance required for the switch, it is still likely to "require examination, adjustment, servicing or maintenance while energized. . .," as stated in Section 110-26(a), and so must comply with the section.

3. Portable cord may be used for permanent installations as long as the use complies with both Sections 400-7 and 400-8. In accordance with Section 400-7, it could well be used for connections to a trash compactor to facilitate frequent interchange, to prevent the transmission of noise or vibration or because it connects to moving parts. However, the cord may not be attached to building surfaces or installed in raceways according to Section 400-8. Therefore, your example does appear to violate Section 400-8.

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Noel Williams

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