Hi I am rewireing an outlet for my stove. 220v 30 amp service.
I would like to know what the colors mean.
Four wires:

1 black
1 red
1 blue?
1 twisted bare aluminium

This wire is to code in my area, (Anchorage AK) I just do not know the hots and the extra ground to connect the outlet.
Thank you
Catherine

The blue is an odd color. The black and red should be both hot, measuring 240 volts across them. The blue maybe a neutral, measuring 120 volts to both the red and black separately. The bare must be the equipment ground, again measuring 120 volts from both the black and red.

AK should be following the NFPA National Electric Code, which does not allow any color other than white to be neutral.

Perhaps these colors are used in Canada, and due to being so close the cable with blue was used as neutral.