The Fluke 6500 tester has two interesting features. After plugging the tester into a mains supply, to adjust the screen brightness/contrast, the display must be at the first screen displaying the mains voltage and frequency etc. Pressing the up and down arrows on the tester will adjust the brightness/contrast.
The second interesting feature is the ‘Limit Calc’ where if the earth bond test fails due to a long lead, you can invoke the ‘Limit Calc’ and select the size of the cable (Cross sectional area in mm2) together with the length. The tester will then re-calculate the correct pass value and the test will pass; a very useful feature indeed. Once the lead has failed on the continuity test and ‘LEAD FAIL’ is displayed together with a cross, press the ‘SETUP’ key to recalculate the limit allowing for the length; the ‘LIMIT CALC’ screen will be displayed and the ‘LENGTH’ field will be in reverse video. Use the up and down arrows to increment or decrement the length displayed to the measured length. Pressing the right arrow key will move the cursor to the ‘SECTION mm2’ field where you use the up and down arrows to increment or decrement the size of the cable. Press the ‘YES’ key to confirm the calculation. The tester will re-calculate the pass/fail limit and the test will pass. On modern cables the size of the cable is embossed or printed on the side of the cable.
One test the Fluke 6200 and 6500 do not do is the newly re-introduced half voltage (250 Volt) insulation test or ‘soft test’. These testers were developed between 2001 when the IEE Code of Practice 2nd edition was published banning the 250 Volt test and 2008 when the IEE Code of Practice 3rd edition was published re-introducing the 250 Volt test.