What is the technical term for the rings that protect holes for electrical through woodwork like cabinets?

Question

I drill holes in cabinets or desks for electrical. I usually drill about a 3/4" hole and I have these little plastic rings I put in to protect the woodwork and just so it looks nicer. Electrical is armored...

So I have seen other examples at builds and I have been a little jealous of their rings. They seem more rubbery and the armor seems tighter to them. This isn't a shopping question. I want to know what these are called and if there are features of these that are better for certain types of electrical or cables.

Answer 1

Grommets

Yeah, one-word answers are not ideal. But a quick search confirms that this is a standard industry term for these objects.

Answer 2

The two types of grommets I use (note: none of these names are official, the official name is just "grommet" which is why there are pictures of each):

Black plastic electrical grommet I'll use these when I have to go through a cabinet wall instead of around, when I expect to change cables sometimes but not often, and when I don't care about dust ingress.

Rubber flap grommet I use these if there will not be wires in the opening and I just want it to look good, or if I care about dust getting in the opening/to the other side. With one or a few small cables, it lets less in than the opening on the other plastic type. These can permanently deform if left with cables in them for long.

Honorable mention: tight rubber flange grommet I'd use a large one of these if I don't care at all about dust ingress. Or if I'm using unterminated cables that completely fill the hole, I'd use one exactly the size of the cable and terminate the cable after I feed it through, this can be close to airtight if desired.

Answer 3

If we are talking about the lining of a hole that is designed specifically for electrical conductors, as to prevent rubbing of the conductor against the sides of the hole, then this is a bushing.

A bushing is also used as the name for this kind of pass-through even when not talking about electrical conductors. The correct term is bushing.

My research indicates that the primary difference between bushing and grommet has to do with whether or not the primary outcome is to reduce friction or to reinforce the walls of the hole. If the former it's a bushing, if the latter it's a grommet.

Answer 4

OP, you mentioned 3/4" holes (which won't fit a PC cord but will fit armored cable (AC/MC). And you mentioned armored, so I assume this is in-wall wiring which is proceeding through built-in style cabinets.

Now OP, no prejudice to your job. Given that you make a point to ask, that is plain evidence that you care and aim to do the work tip-top.

However, many other people with similar questions find our Q&A on Google, and for their sake, let me borrow the megaphone and steer them away from the most common mistake in this area.

Honestly, most cabinet installers get this wrong.

Every junction box must have a cover.

Every junction box cover must remain accessible without tools or disassembly of the building or damage to finish materials. NEC 314.29 and others.

So what happens a lot is people install built-in cabinets and "bury" the electrical junction boxes, so that they cannot be accessed without entirely emptying out the cabinetry and then disassembling the built-in cabinets.

That's not allowed. There must be an access panel, removable without tools, that grants access to the original junction box that is being buried or tapped.

Another way of doing that, if the installer is sharp, is line up the structure of the cabinets so one can put an extension box on top of the 1-gang in-wall box, so the extension pops through the cabinetry. From there it is permissible to bring metal flex conduit into the side ports of the extension (either behind the cabinetry or in front of/visibly inside it perhaps off an extension on the extension... your call) and go onward to points of ones choosing. Of course this isn't easy to make aesthetic.

Answer 5

INKWELL If the hole is vertically down through a desk surface, I've heard them referred to as inkwells.

In the past, desks had a hole for a glass bottle of ink to be positioned, so it couldn't fall over. Example:

Cut to modern times, computers were being set up on office desks globally. Rather than running a bunch of cables over the back of desks, they were often run through a hole in the desk top, with a trim piece looking like this:

The lid pops out to allow larger plugs through, and clips back in to close up around the narrower wire part. The hole is often 60/70/75mm so check first.

Why were these not a thing for telephones? Desk phones were originally hard-wired to the wall, making it more difficult to move furniture. Also they had one single cable which was harder to see and didn't need to be hidden. So flipping over the back of a desk was perfectly acceptable and didn't need a hole in the desk.