While inspecting some multi-section manufactured home installations recently, I noticed some areas needing improvement regarding electrical crossover connections. So I thought we should talk about this issue as we head into the summer season.
One of first things to keep in mind is that you should never have any Non-Metallic Sheathed Cable (also called NM Cable, often referred as Romex®) used for branch circuit wiring visible under a manufactured home. Crossover wiring is always to be tucked inside the floor cavity or walls, and protected with an access panel or hatch.
Secondly, to make this connection most manufacturers generally use either electrical connectors or junction boxes. Connectors are pretty straight forward, just snap them together. Most manufacturers in the northeast use Molex® brand connectors, and the great thing about these connectors is that they have release tabs so you can separate the connectors without any damage and reuse them as needed. This is important for relocating a home, or if the home were on display before being moved to it’s installation site.
Some older manufactured homes used a connector made by Amp® that was a single use connector. If you looked closely, you would see: “One Time Use Only, Do Not Re-terminate”. The issue was there was no release tab on these connectors, so if you pulled them apart the plastic housing would bend and distort the device. When reconnected, the housing wouldn’t be able to connect securely and safety became a concern. The good news is that I haven’t seen these used for at least eight to ten years. But be alert if you are installing older homes as you may see a connector that is not intended to be reused. If so, cut it off and either install a new connector or use a junction box inside an access panel in the floor cavity or marriage wall.
Speaking of junction boxes, here are a few basic things to remember. Where the NM Cable enters the junction box, there should be a cable clamp or connector. Don’t overtighten the clamp onto the cable, just snug it down. The cable should be secured within 12” of the clamp or connector (check the actual installation manual as some require cable securement within 8” of the cable clamp). If the junction box is metal, it should be grounded. You can use a ground clip, ground screw or a “greeny” wire nut for this. Twist the conductors together before installing the wire nut, and make sure to use a wire nut that is the proper size. Usually the capacity and number of connectors are identified on the top of the wire nut itself. After grounding the junction box and making good connections, place the cover on the junction box!
I am seeing a few of the push-in type connectors in place of the twist style wire nuts, and these seem to work fine. Just make sure you strip the conductor with the proper tool to the proper length per the installation instructions. I saw a few brands of these push-in connectors that limited their use to solid wire only (no stranded wire). On solid wire conductors, these push-in types are generally reusable. But it can be difficult to get the conductors to disengage. You may be better served replacing them.
If you notice that the outer sheathing (or jacket) of the NM Cable is nicked or damaged, make sure you address it properly. If there is a superficial nick in the outer sheathing, wrap electrical tape around the cable at the nicked area, to a thickness that equals the depth of the nick. If the damage exposes any of the conductors or the paper inside the cable, the affected area must be removed! There is no repair for damage that significant.
If the manufacturer notched out a wall stud or other structural member to run the NM cable, make sure to protect the cables with wire protective plates or “mash or smash” plates as they call them in the south. And make certain the cable is 100% protected!
Always replace the access panels or close the access area to protect the connection from moisture and possible damage. If any floor insulation is missing, replace it as well!
Revisit the manufacturers installation instructions for a little more detail. On a new home, use the connector type the manufacturer provided. If there are problems making this connection on a new manufactured home, take a picture and report it back to the manufacturer. They can only make improvements if they get feedback from you!
Keep in mind that you should always refer to the Manufacturers Installation Instructions, but if you want to learn more, the Manufactured Home Construction & Safety Standards (MHCSS) at 3280.801 is where you will find the actual code requirements. Click Here for the MHCSS Also, it is worth knowing the MHCSS adopts Article 550 of the 2005 National Electric Code. So, check them all out to make sure you are doing things right!