Hey guys im new so please help. 304 electrical problem
 

So im rewiring a 305 with hei distributor with brand new wiring kit. I connected everything and i took off negative cable off the battery. With key off i proceeded to put a tester light on to look for shorts in the sytem. I attached aligator clip yo negative post and with cable off the battery put test light on cable a 0.1 draw. Now heres my prob. When i turn key to on i retest and now neg cable has 12 volts!! I isolated to wire of distributor if i disconnect wire then the negative goes back to normal. I took off distributor cap/rotor to check if wires inside were grounding and they were not. The car starts fine no problem so is this normal?? Do i have a short somewhere? Thanks guys.

OK, what is your concern? Does it start? Voltmeter reads a potential difference, if you have (test light) on negative, and have a light on (test light) with key on, you have a positive, and a ground. Not sure what you are asking, and am trying to help.

sounds normal to me. this is why if you leave the key on the battery will die

Thanks kevinkpk for your help. Heres a link to a video i made.
Please tell me what you think.