Given the 10-2 feed bringing 30 amps at 120 volts to the shed you have a subpanel where the hot conductor of the feed was pigtailed to both of the top (master) breaker.
A maximum of 30 amps can come in on the feed hot conductor to be split up among the breakers on both sides of the panel. So a maximum of 30 amps can go back on the feed neutral which is also 10 gauge and wil not overload given a proper breaker at the supra panel.
The only caution is, as mentioned earlier, not to wire up any of the branch circuits as a multiwire branch circuit namely one 12-3 with red and black to different (any two) breakers in that panel and sharing the white neutral.
A maximum of 30 amps can come in on the feed hot conductor to be split up among the breakers on both sides of the panel. So a maximum of 30 amps can go back on the feed neutral which is also 10 gauge and wil not overload given a proper breaker at the supra panel.
The only caution is, as mentioned earlier, not to wire up any of the branch circuits as a multiwire branch circuit namely one 12-3 with red and black to different (any two) breakers in that panel and sharing the white neutral.
