We had a brownout at our house on Wednesday that lasted about 1 hour. Per the power company we lost 1 phase. Lights still worked (but dimmed), but other appliances were dead. Went out to find the disconnect to my hot tub fried-completely melted. Based on this, is the controll panel or other parts of the tub most likely fried?

Well I answered my own question and I must be living right.. I bought a CH 50A gfi panel, installed it and whala the tub popped right back on.. Those electronics in that tub must be pretty hardy... I am still waiting on it to heat up.. It appears to be going up, but I will know for sure later.

That damage in the disconnect wasn't a brown-out, just coincidental. That is evidence of a poor connection somewhere in the disconnect and simply over-heating until it melted compltetley and giving you an O/L.. That takes time...

The spa wiring (at the hot tub) never heated up, and is not effected. It only overheated at the portion that is unable to carry the amperage, in this case, in your sub-panel.

When I called the power company, they said that they had lost one phase. I am not even remotely an electrician, but if the tub remained on- attemting to run off of a single phase, would that not have overheated the wires? Never had a problem with this disconnect until this power issue...And only one side of the wiring was fried.... Just curious, I appreciate your thoughts on the matter..

Losing one phase won't over-heat any wires, in fact, it just means that whatever is using that (lost) phase to complete circuit will not function at all, and pull no amperage, thus creating zero heat. There is no load at that point.

Potentially, a spa could still run fine on one phase, if the phase that was still on was the the hot for 110v equip.
Generally, all 110/220v "convertable" spas are basically 110v, with an option to run 220v to the heater only. If one leg of the 220v is out happens to be the leg that powers all the equip and 1/2 the heater, nothing works. However, if one leg goes out that powers only half the heater, everything still works (using the neutral wire to complete the circuit), just no heat.

Ask yourself this, Why did the wires overheat at that particular spot, and no where else? There is no load there that is any different than anywhere the entire length of the run. It was simply the weak link due to a poor connection exactly where it overheated. This takes time, and does not happen from any type of power surge or brown out from the power company. It is simply a coincidence.

Losing one phase is like turning off a light switch to a light. The wire to the switch doesn't get hot when you turn the light off... since there is no way the electricity can complete the circuit, no current at all travels throught the switch, and it remains cool. Turn on the light, however, and amperage will flow through the light switch, creating heat. If there is a poor connection in the light switch, (or anywhere for that matter) it will overheat and melt. This is basically what happened to your disconnect...

You can test this theory quite easily, if you have any double pole breakers in your home that have two switches instead of one. These will usually energize a water heater, stove, heat, or A/C. Just turn off half the breaker....presto- you've just turned off one "phase"
Now, go turn"on" the appliance you've just turned off half a breaker...What you'll find is that the unit will not work at all, and nothing will overheat.
Hope this helps expain, it truly is just a coincidence

It does, thanks for the education!!

Correct me if im wrong but the wiring used in the fried box looks like #10 solid and that would carry aprox 20 amps. A 50 amp circut would need #6 stranded. Dont look like stranded to me. Solid does not come in #6 for simalar applications on home electrical. The picture looks like a heatup over a period of time due to too much amperage draw through too small wire.

Looks like #8 braided from the main panel to the disconnect (should be ok for a run of 100ft or so) and then some very small guage from the disconnect to the spa- glad you noticed! Hopefully rshe is still around, and will notice as well!

Just looked at it.. It is 8 coming in from the service panel....But it appears to be 10 going out to the tub. It has been this way since I bought the house 6 years ago.. Is it an issue?