Is your application for just DC or do you need compensation for HF (Like a scaled up scope probe) ? Also, the load resistance of your meter/s must be consistant as this will affect the ratio. Simple DC method 30 1M, 1000V rated resistors ( or whatever you can find for 30KV) To determine the low voltage resistor (R2) R1 (30M) / Ratio-1 (Lets say 1000/1 ratio) 30M/999 = 30,030.03 (This is the effective tap resistance) Then determine the parallel resistance across your load (meter) to get the proper ratio. (10M * 30,030.03 ) / (10M - 30030.03) = 30,120.48 ohms There are other factors to consider such as temperature and voltage coeffecient and possible corona discharge at above 15KV. This can be reduced with large conductor sizes and potting (difficult to do correctly). Good luck