Power leakage in Mac Pro - normal?

Discussion in 'Mac Pro' started by diazj3, Nov 1, 2009.

  1. diazj3 macrumors 6502a

    Jan 19, 2008
    ... so, ¿is this normal?

    I got my 2009 2.66Ghz Quad Mac Pro with the ATI4870 graphics card a few weeks ago. I noticed that when the machine is off, but connected to an ungrounded (or shared with other devices) electric outlet, the whole case gets electrified and power leaks to it. If one's touching it the machine and making direct contact with the floor, it gives small-pulsing-continuous electric shocks.

    I reported it to Apple and took it to an Apple Service center, where they have a robust grounded installation, so nothing showed up.

    I worry that - regardless of the electrical installation (my studio's electric ground has been now reinforced with a direct ground from the MP's outlet), there is something wrong with the internal power source unit - e.g. not being properly isolated from the rest of the case - and/or that this leakage might damage some of the electronics of the machine. What do you think?

    Has anyone else come across this? Thanks!
  2. Techhie macrumors 65816


    Dec 7, 2008
    The hub of stupidity
    I can assure you that this is NOT normal, and should be reported to the AppleCare phone support immediately. Tell them that you need a new power supply, but only after testing to see if it is your power source or not by using a grounded surge protector.
  3. diazj3 thread starter macrumors 6502a

    Jan 19, 2008
    Thanks Techhie...

    As I say, the shocks are only palpable when the machine is connected to an ungrounded outlet. In my studio this doesn't happen anymore, since I asked an electrician to reinforce the installation with an extra ground cable - after that, the shocks are gone, as they were in the Apple Service lab.

    But the shocks are still present when I plug the machine into an ungrounded outlet (with and without surge protector) such as in my girlfriend's house.

    I called Apple, and they directed me to the the local service rep - who said they found nothing. I asked Apple for reassurance about this being normal when using ungrounded electricity - but after 1 week, I haven't heard back from them.

    Any thoughts?
  4. pianojoe macrumors 6502


    Jul 5, 2001
    N 49.50121 E008.54558
    Are you saying that ungrounded outlets are still allowed in your country?
  5. diazj3 thread starter macrumors 6502a

    Jan 19, 2008
    well... some old (but great, pre-WWII) buildings (high ceilings, great space, great location and architecture) still have ungrounded installations. I lived in the US for a while, and that's not uncommon there either... and if government allows them or not, that makes little difference. But that's not the point... I know grounded installations are a must.

    The question is, if it's normal for the Mac Pro to have this leakage. Grounded or ungrounded outlets, I think that's another issue, since the ground will only give the leak a way to drain out... but the leak will be there nevertheless.
  6. nanofrog macrumors G4

    May 6, 2008
    It has to do with SMPS (Switch Mode Power Supply) designs. If the unit is ungrounded and an non-isolated implementation, you get 1/2 AC to the case. This happens to be the standard computer PSU, and it has to have a 3 prong plug for safety reasons. Those used in laptops are usually the isolated type (2 prong cords). If there's a fault

    Simply put, you need a grounded outlet. If you read the manual, it will indicate it requires a grounded outlet (which is why it has a 3 prong IEC connector on the back). If you don't have one (i.e. old buildings, where the existing wiring is "grandfathered"), you need to call an electrician, and have one installed according to local, state/province, and national electrical codes applicable to your location.

    I had to do the same thing to where I'm living now, as the structure's construction date preceeds grounded outlets. Ultimately, it required placing a ground rod, running ground lines to the selected outlet boxes, and use a GFCI (Ground Fault Circuit Interupt) for the circuit's rated amperage. That's the US though. Likely something similar where you're located.

    Hope this helps. :)
  7. MacKiddyWiddy macrumors 6502

    Aug 18, 2009
    get it sent back and ring up the apple care, that isnt normal [​IMG]
  8. HellDiverUK macrumors 6502

    Oct 24, 2009
    Belfast, UK
    Well actually, it is totally normal. Grounded is required.
  9. tri3limited macrumors 6502

    Jun 5, 2008
    I get this with my MBP when i take it to work and plug it in. Being a grade II listed building means that a large number of sockets are pretty darn old!
  10. nanofrog macrumors G4

    May 6, 2008
    MBP's are an isolated design (required for laptops in metal enclosures as a safety measure), but they have a history of shocking users. Search MR, as there's a thread or two on it. Wiring comes in contact with the aluminum case, and you get zapped. You do need to take it in for service if possible.

    In the OP's case, the issue is due to the fact a 3 prong plug (ground required) is being used in a 2 prong outlet, so the ground has been circumvented. It's a non-isolated design, and needs the ground to operate properly.

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