I looked at the connection again, and noticed that the ground is not insulated, so I can't use it as a neutral.

Here's another scenario my electrician presented:

I'm actually installing 2 ovens, and he said we could connect both of my wall ovens to one junction box instead of using the wiring from the microwave. There is already a juntion box in place for the lower oven. The lower oven is rated 240V 20 amp and the upper is rated 240V 30 amp. Is it safe to connect both ovens to one box and use a 50 amp double pole breaker? The breaker in the sub-panel appears to be rated for 50 amps for this box, and the wiring in the junction box is very thick (It was used on the old oven that I recently removed - it's definitely not the same type of wiring that was in the 120V outlet).

Is this safe? Thanks.