We recently moved into a home that had a hot tub at one time (since removed). There is an existing 50A circuit from the main load center to an exterior load center (Siemens W0408ML1125) mounted on side of the house. Within that panel is a 50A GFCI breaker and from there are four 6AWG wires running in buried conduit to the location where the hot tub was placed. Now, I'd like to place a water fountain in that location.

I'd like to install an exterior receptacle to power both the fountain and maybe some low voltage lighting. Note that the run from the load center to the disconnect box is inside a finished ceiling and wall with no easy access.

Can I just remove the 50A breaker in the exterior sub panel (along with the 6 gauge wires in the conduit) and replace with 20A breakers and some 12-gauge wire running to two different outdoor receptacles? Is there a better option?

First you must determine if this is a 240/120 circuit or a 240 circuit.

Assuming that it is a 120/240 circuit, is the disconnect a pull out fused disconnect or does it use circuit breakers?

If fused pull out disconnect remove one fuse. Replace the other with a 20 amp fuse. If breakers are used replace with a single breaker and a blank cover.
For additional safety you could also disconnect and cap the unused wires with a wire nut.

At the former hot tub location cap the unused line with wire nut. Connect a 12 gauge pigtail to the neutral and the other hot. Install receptacle. If circuit breaker in panel is GFCI, or breaker at disconnect is GFCI, a regular outlet can be used. If breaker is not GFCI install GFI receptacle, wire out of the load terminals of GFI to fountain if fountain is not cord and plug.

Thanks for the reply. I went out and further investigated the exterior box and found that it is not just a disconnect but, rather, a subpanel with a 50A breaker. I had originally stated that it was just a disconnect and you may not have seen my edited question. Sorry, I should have made certain before posting the question.

Anyway, the 50A breaker in the main load center is a 2 Pole Type QP 120/240V (L5538). The 50A breaker in the exterior sub panel is a 2 Pole Type QPF 50A GFCI breaker.

So, if I understand your advice correctly, I would:

-Remove the 50A GFCI breaker in the exterior subpanel and replace with a 20A GFCI breaker.

-Use only the black, white, & green wires (removing or capping the red wire) in the conduit between the subpanel and the hot tub/fountain location.

-At the fountain location, I bond 12-ga wire to the 6-ga wire (pig tails) and terminate on a standard 20A receptacle.

Is that correct? Would it be simpler to pull new 12-ga wire through the conduit rather than try to attach a pigtail in the receptacle box? If I were to use a pigtail, what is the best way to bond the 6-ga to the 12-ga?

Thanks again for the help.

Add a 12 pigtail with a wire nut.
Would be less expensive to replace breaker with regular breaker and use a GFI outlet. Also be more convenient to reset if you have a GFI trip
You may or may not be able to get 6 gauge wire to 20 amp breaker. If not, simply put a 12 gauge pigtail on 6 gauge wire at disconnect with wire nut. No need to discard existing wire in conduit from disconnect to fountain. You may or may not be able to find a blank cover to seal the unused breaker hole. If not, just use another breaker and leave it unconnected.

This is assuming that this is a 120/240 volt circuit, black, red and white, between panel and disconnect. If not, you will have to rewire to make it a 120V circuit.

OR

The least expensive way would be to replace the breaker in the panel with a 20 amp breaker. That way you need only a 20 amp breaker and a outlet. Replace existing double breaker with a single regular 20 amp breaker using a pigtail to connect to one of the #6 wires. Cap the other with a wire nut. Install an outlet and connect to the fountain. The existing breaker in the disconnect will serve for GFI protection.

Ok, that makes sense. Thanks for the help.

Using Existing conductors is cheaper, less work. Good Info from HK.
You could also. Remove # 6's from Fountain box, Pull a Black, Red, White and Green(#12). This give you a Circuit for Fountain and a circuit for landscape lighting. Easier to work with in the future. This would be a Multi Circuit(2 circuits on opposite phase sharing a Neutral). 2 Pole Breaker would be needed, Or pull additional Neutral