Enclosure lubricants

Q
Is it permissible to put grease on the machined surface of either a box or cover where these are suitable for Class 1/Division 1 locations? Also is it suitable to use these type enclosures and covers in outside applications? I see this done all the time. I'm aware that if an enclosure is suitable for hazardous locations, that doesn't make it rain-tight. The reason for the questions is that I was called to repair stop-start buttons that had been broken. My intention was to remove the cover (machined surface, with four bolts in the corners) and just replace the cover with new buttons in the cover. When I removed the cover, there was a lot of grease on the machined surfaces of the cover and box.

I questioned the reason for the grease and was told in another application they were having trouble with water entering the manu-facturer's Disconnect (Class 1 Division 1 machined surfaces) that was also being used outside. I was told that there was grease approved to make this enclosure rain-tight and that it was UL approved. It was reasoned that if they could use it on the disconnect, they could use it in other similar applications. My response was, “If this is true, I would like to see some documentation.” For the most part, this is a pump application with a pump, motor and with a manual starter mounted on a cart. They are in a building when they are in use and are stored outside when they are not in use. Any Code reference or any other documentation that might answer these questions would be helpful.

A
Thread and joint lubricants are available from the manufacturers of explosion-proof equipment. I checked several catalogs and found both conductive and non-conductive lubricants as well as high-temperature products. Only lubricants provided by the same equipment manufacturer should be used. Untested lubricants may affect the escape of hot gases in the event of an internal explosion. If hot gases escape from the enclosure, the results could be disastrous.

Catalog information states that these products inhibit corrosion and reduce the entry of water. They make no claims about keeping water from entering the enclosure if the lubricant is used. They also make no claim that the product will make an indoor enclosure suitable for outdoor use.

It's amazing how these fairy tales grow. One person hears a product will reduce water entry. Before long, it was said this same product would make an enclosure rain-tight.

The general information in the Underwriter Laboratories Hazardous Locations Equipment Directory provides information on environmental considerations. Hazardous locations equipment is intended for indoor use unless otherwise marked. If suitable for outdoor use, the equipment will be marked with an enclosure type number (often called a NEMA number).

Section 110-11 requires that equipment used in damp or wet locations be identified for the use. Enclosure type numbers provide the identification required by this section. Section 430-91 provides a handy reference for an enclosure type number. This section covers motor controller enclosures; however, the numbers are the same for other enclosures.
Dann Strube

Carnival receptacles

Q
My question concerns Section 525-18, Carnival receptacles. We are currently rewiring a community center grounds where a carnival takes place each year for three days. There are poles on which we plan to mount circuit breakers that will protect receptacles. (Three 125V receptacles — 1A through 30A single-pole and two 20A single-pole). The receptacles normally feed cord-connected food trailers or lighting at a game stand. Throughout the year they could be used for anything, but they normally aren't used after the carnival is over. I've asked this question from time to time at other carnival grounds and need to set a standard to use at all the locations around my area. Will you please clarify this?

What is the definition of receptacles for personnel? How does 525-18 apply in our situation? (a), (b), or (c) — or some of each? Do I allow the community center to enforce an assured grounding program?

A
Currently, there is no general requirement for GFCI protection of receptacles located outside except at residential occupancies and on rooftops. This may change in the 2002 Code. However, during the time of the carnival, certain receptacles are required to have GFCI protection. Section 525-18 provides three categories: (a) 15A and 20A, 125V receptacles used by personnel but not for use with certain specific appliances, (b) receptacles for those specific appliances and (c) others. In your case, the 30A, 125V receptacles fall under either (b) or (c). The 20 A receptacles fall under (a) and will require GFCI protection at least during the carnival, but not the rest of the time unless they were used for temporary wiring as covered by Article 305.

Assured equipment grounding programs can be used only with other than 15A or 20A, 125V receptacles, but GFCI protection is also an option for these receptacles.

In the situation you describe, the use changes from time to time and with the change in use comes a change in rules. In my opinion, the easiest and probably most prudent thing to do with this situation is provide GFCI protection for all the receptacles. That way you are covered for virtually all uses, unless an appliance will not work with the GFCI.

In my view, all receptacles are for use by personnel unless they are dedicated to a specific appliance that is always plugged in. Otherwise, as far as I know, only people use receptacles. Although an assured equipment grounding program could be used, someone would have to be there to inspect, test and identify every cord, tool and appliance that is plugged in. This may be practical for the three days of the carnival, but note the requirement: “continuously enforced at the site.” As I said, I'd use the GFCI protection, even though this could cause problems with some appliances.
Noel Williams

Metal-enclosed switchgear

Q
An industrial client would like to install in a plant production area some metal-enclosed switchgear consisting of a 4,160V switch, 4,160V to 480V dry transformer and 2,500A main 480/277V switchboard. Since all of the gear is metal enclosed, is there a need to provide a separate room or barricade fencing around it?

A
This answer is based on the 1999 NEC. Several sections apply to your proposed installation. Your 4,160V equipment is covered by Section 110-31. Since you specify the equipment is in a plant production area, I will assume it is indoors and accessible to unqualified persons. Section 110-31(a)(1) provides the rule you need. Your metal-enclosed equipment does not need to be fenced or located in a separate room, however, your equipment must meet the construction requirements given in Section 110-31(a)(1). This section also requires appropriate warning signs. Section 110-31(c) also states the same construction requirements and further requires protection from vehicular traffic. Section 110-27(a) covers the 480/277V equipment. A room or fence is not required for metal enclosed equipment. Section 110-27(b) requires protection from physical damage so equipment such as forklifts must be considered.
Dann Strube

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