June 18 (Reuters) - So far this week, Texas and California have passed a major heat wave test that stressed their power systems with record demand, lots of forced generation outages in Texas and scorching weather across the West that reduced imports into California. High temperatures topped 110 degrees Fahrenheit (43 Celsius) for much of this week in parts of several Western states including California, Arizona and Nevada. Power grid operators in Texas and California urged consumers to conserve energy this week to reduce strain on the electric system and avoid outages as homes and businesses kept air conditioners cranked up. Over the past year, both Texas and California have imposed rotating or controlled outages to prevent more widespread collapses of their power systems - California during a heatwave in August 2020 and Texas during a brutal freeze in February 2021. Although both grids kept calls for conservation in effect for Friday, temperatures, power demand and prices were all lower in both states compared with earlier in the week - though anything can happen if a major power plant or transmission line fails. In Texas, the Electric Reliability Council of Texas (ERCOT), which operates the grid in most of the state, said demand peaked at a June record on Monday at 69,943 megawatts (MW). But with hot weather expected all summer, ERCOT forecast demand will keep testing the June record with a projected high of 70,314 MW on June 21 and 70,481 MW on June 25. One megawatt can power about 200 homes on a hot summer day. The California ISO, which operates the grid in most of that state, said demand this week peaked on Thursday at 41,364 MW and was expected to come in close at 41,349 MW on Friday, the last hot day. Reporting by Scott DiSavino Editing by Chizu Nomiyama Our Standards: The Thomson Reuters Trust Principles.