Replacing Romex with MC flex cable - boxes and connections

[C tone]

I am replacing some ungrounded 50 year old 2 wire romex with Metal Clad flex cable and was hoping to use the boxes that are in place. They were installed in the 1960's, 2"x3"x2 1/4" in width, height, depth. As can hopefully be seen in the picture, there is a clamp with two openings and a tightening screw holding the romex in place.
Is using the clamp and screw up to code if used with MC or do I need to either switch out the box or
use a different connector in the same box? The wire is being fed from a crawlspace, the distance being about a foot from the crawlspace to the outlet. There are about 30 outlets that are identical and will need to be changed, so am trying to figure out the most efficient way to do this without having to damage the walls.

 

[Cacher_Chick]

Time to do a box fill calculation.

 

[Sponsor]

 

[Cacher_Chick]

By my count, you will need to go to a 3-1/2" deep box. If it were my house, I would just do a little at a time based on which location really had a need for an EGC. Kitchen, bath, garage, workshop, basement, etc. Very few cord and plug devices in a house have an EGC. Unfinished basement and garage spaces need GFCI protection, and do not require the addition of a EGC if it is old work.

 

[C tone]

Thanks for the replies. It does appear that I will need to put in bigger boxes. The boxes that are in there
have rounded backs which cuts into the overall space available quite a bit. I have another question. I have a couple of outlets that were
put in on a new separate grounded romex circuit. Is it ok to put a junction box about half way between the outlet and the
breaker box and splice in MC flex cable for the distance from the junction box to the outlet, in other words, mixing romex
and MC cable on the same circuit?

 

[Cacher_Chick]

As long as the junction box remains accessable, there is no problem with that. If you mix wire gauges or temperature ratings, the breaker must be sized to the lesser wire on the circuit.