@Helen Zhang Try Elliot Electric supply.

The supply side seems endless for a long time. 

It sounds like you have a great supply, short of funds, but what about demand?

The $20 you saved on buying a years supply of Toilet Paper, did you put that in a separate account or spend it on the next purchase?

Supply/demand: your supply of "one 55+ duplex" isn't going to change, but the number of 55+ people 'demanding' to live in it might drop off, drastically reducing rents and/or resale value.

Realtors can supply great contracts for your market.

It's a different tenant dynamic than many other places.Of course, it hasn't always been this ideal from a supply/demand perspective for landlords, and won't stay this way indefinitely.Why not use your OK houses as your bread and butter and invest opportunistically here in SD if you find something interesting?

Is the supply of potential units becoming tight and prices rising? 

Menards - lowest overall prices with good quality for the supplies that I purchase. 

Theoretically, when the box is pulling at 100%, the 60 amp service will be trying to supply 100amps, and that will stress the service wire (a potential fire risk, not to mention the electric in the house may seem to waver...).