Hi, I wanted to conduct some survey of the common practices (which may or may not be good practices) to powering your very own mini and maxi big iron in your home. I think this topic may be embarrassing so PLEASE let's wait 10 days or so before flaming and blaming each other for our risky ways of squeezing the last amp out of our feeds. I would hope that in the end we could summarize in a calm and sensible way what the general suggestions might be to a safe but reasonable way of running equipment. Here I go then. As you know, I have two hot-spots: (1) 2 VAX 6000-460 and 8 to 10 RA90 and 2 RA8x and one HSC90 that I run in my basement. I have a dedicated 60 A 220 V 4-wire line going right into that room. I have terminated that line in a circuit breaker box and feed the computers with a 25 A 220 V line. This is about 6 to 9 foot cable of AWG #10 that I run without a metal conduit. (The other breakers feed German household stuff that we still have in use here and there.) I noticed that when I have everything on, the 25 A breaker gets warm. Fairly warm. Not hot, but markedly warm. I made sure the wires are screwed very tight and the breaker is seated right, but still it gets warm. That worries me a bit. Also, I think that my #10 wire is under-dimensioned after all. Since all the consumers are essentially doing some (more or less) good job of load balancing, eventually the neutral wire gets quite a bit of load, possibly beyond 25 A. Theoretically up to 50 A. So, I should have used #8 or even #6 then. However, the practical problem is that you can't fit #6 wire into a breaker contact screw. And even #8 is going to be on the low end with 50 A. The best thing would be if neutral was twice as thick here. I am considering to put in two lines in parallel from the same breaker through the same conduit (if any) the outlets very close together. (2) The VAX 11/780, UNIBUS, TU78, and TE16 in the garage. They run off the same line (so that line is no longer dedicated.) I spliced a branch off with split bolts and lots of electric tape. for insulation. The branch terminates in a dedicated box with the original outlets. The initially #8 AWG is distributed through #10 wires to the various outlets. Even some #12 to the two standard 110V outlets in that box. My concern there is, of course, that (a) the split bolt construction may develop resistance and increased heat dissipation. Also (b) the way I downsize and distribute the #6 feet to smaller wires in the outlet box may lead to overcurrent if the devices aren't connected where they should. I did my best to have the big suckers on thick AWG and shorter length than the moderate consumers. On the other hane, turning the VAX 11/780 on is an extremely rare event right now and will probably be in the future. Some hours per week perhaps. I was concerned about what to do whe I have my VAX party (when everything works.) If we want to turn it all on at the same time, something might happen... I regularly check the warmth of that breaker downstairs and now that that spplit-bolt tap is insulated I can check that for heat. But it's nothing I want to run 24/7 without attention. So, I know I have to do something about it. I usually take the circuit off line when I am done with it. The problem of course is that to do it properly would require upgrading the main feed, replacing the main breaker panel running thousands of new wires, and sub-panels, where each machine essentially has its own breaker, and of course the outlets and plugs need to be all proper. Easy to spend $2000 or more in material and labor for that upgrade. For equipment we run a few hours per week. I'm really interested in hearing how others with minis do it. (If you don't have a mini yourself but want to teach the dangers of electricity and the demands of the NEC, please hold off for 10 days, O.K.?) Any good or bad example is welcome. regards, -Gunther -- Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org Medical Information Scientist Regenstrief Institute for Health Care Adjunct Assistant Professor Indiana University School of Medicine tel:1(317)630-7960 http://aurora.regenstrief.org