The hydromassage zone
A typical scenario I come across as an electrical inspector is a bathroom receptacle on the wall beyond the end of a countertop. The receptacle clears the vanity mirror and is above a tiled shelf at the end of either a hydromassage or non-jetted tub, without glazing or curtains. Section 680.71 only requires GFCI protection within 1½ meters of the inside tub wall. This is the rule I use for inspections when there is no enclosure. Basically, without enclosing curtains or glazing, I look up vertically from the tub sides to define this “space.”
Some have tried to define the “space” referred to in Section 410-57(c) [406.8(C)] as the “3-ft horizontal zone” defined in 410-4(d) [410.4(D)], which is clearly not stated or linked by reference. Articles 550 and 552 use 750 mm as the distance to maintain between receptacles and tubs or shower spaces, while Article 680 uses 1½ meters between spas or hot tubs, and receptacles or switches. Proposals have been made to put a limit on these distances, but an emphasis is needed on defining the tub or shower “space” first. This area, or space, is not NEC-defined for tubs and showers other than by enclosures such as curtains or partitions, or listed assemblies. What do you think?
As you have noted, Section 410-57(c) [Section 406.8 (C) in the 2002 NEC] prohibits a receptacle from being installed within the shower or bathtub space. The NEC contains no reference to link this “space” to the space described in Section 410.4 (D).
If a hydromassage or standard bathtub is installed in a bathroom, then Section 210.8 (A) (1) or (B) (1) would require any 15A or 20A 125V, receptacles to be GFCI-protected, regardless of their proximity to the tub or shower space. However, if a standard bathtub were located in an area that was “other than a bathroom” (no basin) then the requirement for GFCI protection would be based on the specific area itself.
Most of the freestanding tubs that I have seen lately, located outside of bathrooms, were of the hydromassage variety. Section 680.71 requires any single-phase 125V receptacles, up to 30A, located within 5 ft of the inside wall of a hydromassage bathtub to be provided with GFCI protection.
In regards to defining the bathtub space, it seems the NEC panel statements in the rejected proposals you mention in your references have one thing in common. The NEC panel was concerned that prohibiting receptacle outlets within a 3 ft horizontal measurement from the rim of the bathtub (the 410.4 (D) space) would create a problem in bathrooms of limited size. If no wall space was available within 36 in. of the outside edge of the basin, it would conflict with the mandatory wall receptacle outlet requirement for dwelling unit bathrooms found in Section 210.52 (D).
If the NEC receives substantiation for a change, then perhaps a proposal that considered bathrooms with restricted space would address the panel's concern. Similar proposals related to swimming pools located at dwelling units with restricted lot space were accepted in principle by CMP 20 during the 2002 cycle.
Mark R. Hilbert
Isolated grounding in 2002
In Noel Williams' reply to the “Power and data share raceway” question in the May 2002 Code Guide, he cites the 2002 Code, not the 1999 Code referenced in the question. This got me to thinking: In many jurisdictions, the 1999 Code is still the authority, but this will soon change.
I have briefly reviewed the 2002 Code and note that the sections regarding isolated grounding have been deleted, moved or perhaps renumbered. The sections that we reference in the 1999 Code are 250-74 EX 4, 250-75 EX and 384-20 EX. These sections are not in the 2002 Code. Where have they gone?
The references you gave are actually from the 1996 NEC. In the 1999 NEC, the reference to 250-74 Exception No. 4 was revised to become 250-146(d).
In 2002, this reference became 250.146(D). What was 250.75 Exception in the 1996 Code became 250-96(b) in 1999 and 250.96(D) in 2002. These two section changes were made as part of the general rewrite of Article 250 that appeared in 1999.
The other reference to isolated grounding conductors in panelboards did not change until 2002. Actually, the language in the exception referred to 250-74 in 1996 and to 250-146 in 1999, but otherwise the rule did not change. However, Article 384 became Article 408 in the 2002 Code because panelboards more logically fall under the Chapter 4 heading of equipment than under Chapter 3 wiring methods. Now what was Section 384-20 has become 408.20.
The 1999 NEC has a cross reference between old (1996) and new (1999) versions of Article 250 that can be found in Appendix E. The 2002 NEC includes a cross reference between the old (1999) and new (2002) versions of Chapter 3 in Annex F.
Green hexagonal self-tapping screws
Section 250.148A states that a connection shall be made by a grounding screw or a listed grounded device, but according to Section 250.126, a green hexagonal (and not easily removable) screw can also be used. Is a hexagonal self-tapping screw legal according to the NEC? My company is rewiring a house built in 1950, which is done completely in steel boxes and steel flex. Should I buy a tap and die set to install prefab grounding screws or prefab pig tails, or can we use hex head self tappers? To stay within Code, should we paint them green? Section 250.126(3) states that the screws should be identified with a distinctive green color. I understand that 250.126 refers to devices, and that 250.148 refers to grounding of metal boxes. I am still lacking the information to protest against the AHJ, who says I must use a prefab green hexagonal grounding screw for all metal boxes.
You have already quoted most of the sections that apply to your question.
The requirement for a green screw does not apply here as it applies only to device screws and screws used as main bonding jumpers according to 250.126(A) and 250.28(B). Section 250.148(B) is the main rule in this case, and it requires only a grounding screw used for no other purpose or a listed grounding device. The screw is not required to be green. However, Section 250.8 states, “sheet metal screws shall not be used to connect grounding conductors to enclosures.”
I'm not sure “sheet metal screws” is a well-defined term, but I take it to mean screws that are thread-forming. Sheet-metal screws form threads by slightly deforming the sheet metal and forming essentially one thread in a sheet of metal. Most so-called self-tapping screws don't really self-tap. Rather, they are thread-forming screws with or without drill point tips.
Screws that are truly self-tapping actually cut a thread that will accept a machine screw. Many of the screws provided with grounding terminal bars for panelboards have screws of this type (that actually cut threads) and they are usually not green. Some screws of this type have drill point tips as well.
Many grounding screws and the screw holes provided for grounding screws have 10-32 threads (No. 10 screw size with 32 threads per in.) and will cut or engage three or four threads in a typical 1/8-in. sheet-metal box.
In my opinion, a screw that cuts such a thread should be permitted as it is equivalent to tapping a hole and then inserting a screw. But some may disagree that such screws are actually “grounding screws,” primarily because they are not green. However, as noted, green is not a requirement, and many of the green screws used for grounding are not necessarily listed as grounding screws either. I don't believe that Section 250.8 is intended to require that such screws be listed. If it did, then the bolts used to attach a listed compression-type lug to an enclosure would also have to be listed.