Adding Circuit To Breaker Panel

I want to add a new 20a/120v circuit to an existing surface mounted circuit breaker panel. All knockouts at the top of the panel are being used. Therefore I would like to use a side knockout. The panel backboard is mounted on 2x4s and spaced out from a concrete block wall. Basement is unfinished.

Can I come down the face of the wooden backboard and surface staple Romex? If ok then make a cable side entry into the panel. Are there limits as to how much exposed Romex can be surface stapled? Are Romex cables installed using this method considered protected?

or

Do I need to come down behind the panel backboard with the Romex? Then drill the backboard a few inches to the right of the panel knockout -- then feed the Romex through from behind the backboard and enter the side knockout? Then no surface stapling of the Romex is required. This sounds like the correct method -- if so how much Romex can be exposed between the hole and the panel knockout once you come through the panel backboard?

or other?

Thanks again,
Bob

 

Use BX (armoured cable) and you can have it exposed. An angle connector would make for a tidy install.

You could also use a duplex connector on one of the existing cables. That lets you put two cables to a single knockout.

 

Code says that romex, or "NM" cable, must be protected from physical damage. Whether or not an installation of NM is subject to physical damage is left to the discretion of the AHJ, or authority having jurisdiction--the inspector. While the surface mounted NM installation isn't acceptable in many applications, surface mounting it in the immediate area around the panelboard would probably be overlooked in this situation. I have seen many installations done in this fashion that have been passed by various AHJ's.

Your idea of running it behind the backerboard and coming out of a drilled hole near the panel offers more protection than a surface mount install. If you go this route, make sure your hole is drilled far enough away from the panel so you can make a gradual bend that's within acceptable bending limits.

The best thing to do in this situation is to ask the inspector what he/she feels is an acceptable method of installation.

 

Thanks for the guidance guys,

If I were to use BX (either surface applied or run behind the backboard) from the panel to the floor joists above the panel (about 4 to 5 feet) are there any restrictions in transitioning from BX to NM by using a junction box? Would this technique be acceptable for more than one new side entry circuits?


Thanks again,
Bob

 

If you were to use BX you could make your transitions in a junction box mounted in the joist space above the panel. You would need a BX connector for the box and panel and red anti-short bushing inserted into the ends of your BX. Then you could use a duplex BX connector, as the other poster suggested, and get the wires from two cables to enter into just one hole in the panel. Or use two, or more, separate BX connectors at the panel and allocate 1 knockout for each cable. Just make sure at the junction box your bare conductor in the NM is bonded to the box and the green conductor, if present, from the BX. And make sure the junction box remains permanently accessible.

Are you sure you need to go with the BX? How are the existing wires brought into the panel? NM is much easier and will save you the hassle of installating separate j-boxes for your transitions.