I've posted on aspects of this before, and d-day is coming.

The situation is this:
A fuse panel upstairs is being eliminated, and the #14 bx cable extended
down about 10-15 feet to a new surface mounted breaker panel downstairs.
Thirteen separate bx cables, 7 of which are 3 wire (Edison), for a total
of 20 circuits.

Should I extend each bx cable with its own extension bx (or romex), or get
one or two 3/4-1" greenfield cables with sufficient #14 conductors pulled
through?

I'm leaning toward the greenfield, as it's just neater, less bulky, fewer
knock-out connections, and I believe a lot more economical.

Opinions? Pros/cons of either strategy?



*I'd go with 3- 3/4" or 2-1" flexible conduits since you will have a total
of 33 conductors plus a grounding conductor in each conduit. Using the
conduits will make it easy to pull additional circuits in the future if
needed. Single conductor wire is cheaper than BX cable.

Check tables C.3, 310.15(B)(2)(a) and 310.16 for more information.