Grounding a ceiling fan with FMT conduit present

Question

I am replacing a recessed can light with a new ceiling fan/light. The old housing is a 6" HALO 7HT like this:

Inside the metal box there are 2 bare copper ground wires connected. Inside the conduit there are only the white and black wires. The fan assembly has 2 green ground wires and installation guide says "Connect the ground conductor of the 120V supply (this may be a bare wire or a wire with green colored insulation) to the green ground lead(s) of the fan. When using standard ceiling mounting, there are two green grounding leads; one from the mounting bracket and one from the hanger ball/downrod assembly"

My problem is that the 2 green ground wires from the fan assembly cannot reach the 120V ground connector inside the metal box. The conduit does not contain a ground wire. Am I supposed to fish one through the conduit and attach at each end? Is the conduit itself grounded? Bottom line: how do I safely and properly attach the 2 green grounding wires of the fan assembly using the conduit and metal box that are in the ceiling?

So I believe what I am reading is that if I connect the conduit to the box with the connector (black), I can then hook the 2 green ground wires from the new fan / light to the grounding screw in my new box (blue-green in the above pic, not yet screwed into the box in the below pic).

1- correct? 2- the connector is plastic....do I need a metal one?

Answer 1

The FMT coming from the box should be grounded. You need to check this with a volt meter. Connect the FMT to a metal fan rated box with the appropriate connector. Then, with the power on, check the voltage from the fan rated box to the black wire from the FMT, you should get 120V+- if the box is grounded through the FMT. Turn power back off. Then take the two ground wires from the fan/bracket and attach them to the fan rated box. Connect the black and white from the FMT/box to the fan. Attach the fan to the box and you should be good to go.

Answer 2

Remove the old metal box altogether

The “fan light assembly” includes that ring which left in the ceiling, and also the metal junction box which the wires now (I guess?) come into.

Normally when you remove a can light, you remove that entire kit-n-kaboodle as an assembly. You carefully disconnect and pull the Romex/NM cables (unsheathed wires, bare wire ends and all) out of the metal junction box that is part of the can light. The entire can light assembly goes away and you are left with 1-3 NM cables and a hole in the wall.

Next, you re-route the NM cables directly to the new fan box. Then hook them up as appropriate.

If there are 2+ NM cables in the old box, one is wise to carefully mark each sheath in some way, and capture the old hookup method with markings. Either just put numbers on them and take photos, or I would write down their function - For instance the cable whose white wire is nutted to other black(s) is a switch loop.

Or, use the old junction box as a splice box—- oh, wait.

OK, here’s the disclaimer: You cannot “bury” a junction box in a way which is inaccessible. Now, can lights can sorta get away with that, because there is often access through the can opening, and in fact, UL specifically approves this application according to UL White Book standards. But your clever “re-imagining” of the design, well, that voids the UL listing. So now we must review the “accessibility” issue anew.

If you have attic access, you can use the box. If the only access to this box is the UL-prescribed method “through the can hole”, then no: your fan bracket blocks that route. You cannot use the old junction box as a splice box, and you must go back to my top solution.

So let’s assume we cleared that hurdle...

You need to get ground from the legacy steel box to the new fan steel box. I see 3 ways to do that.

1. Use the metal sheath of the armored cable. This will require getting an appropriate fitting to allow it to enter a 1/2” knockout.

2. Run a separate ground wire, bolting onto each box somehow at each end. The wire can either enter the steel box through a cable clamp and join the existing grounds, or it can simply connect to the steel box itself. Either through a bolt-and-nut, or the gold-standard way is to drill a hole appropriate to be tapped for a #10-32 screw, and then either tap it with a tap, or just use a self-tapping 10-32 screw. You’re also allowed to use 8-32. The thread pitch must be -32 or finer; no sheet metal screws allowed.

3. Replace the armored cable with familiar NM... with appropriate cable clamps on both ends. I don’t need to tell you how to wire that!

Answer 3

Flexible metal conduit can be the grounding method NEC 360.60. If you would like it is acceptable to pull a longer ground from the fan to the box. Your fan rated box is where the connection can be made the flex metal to metal box is fine use a green screw (may be in the box) 10-32 to connect your grounds if not long enough connect a bare wire or green insulated to the green screw then use a wire nut to connect the 3 together. I mentioned fan rated box because ceiling fans require listed boxes to support ceiling fans.

Answer 4

The installations instructions don't go into detail that you can establish the required ground wire from a ground screw in a metal junction box if the box is properly grounded.

A junction box can be grounded by a ground wire or by an acceptable metal raceway. FMT (and FMC which you probably actually have) is allowed to serve as the equipment ground only if the combined total length of the flex does not exceed 6 feet. Otherwise a ground wire will need to be pulled into the flex, then spliced to the box and the fan.