[c-nsp] Multiple power supply failures. Advise needed

[Michael Ulitskiy]

Justin,

I'm not going to argue an importance of proper grounding. Also I do want to thank you for your reply.
At this point I really doubt that the problem is grounding related, but I'll definitely keep that in mind.
Also in my experience I've never seen a place where every piece of equipment would have a separate
grounding wire attached to the chassis. As far as I can tell this is a standard procedure: grounded outlet,
grounded racks and equipment screwed to the racks.

Michael

On Tuesday 01 September 2009 06:03:03 pm Justin Shore wrote:
> Unless you scrapped the paint off of every joint between the chassis 
> through the mounting brackets to the rack then you aren't guaranteed a 
> good connection.  That's why most telco screw kits come with the star 
> washer to help scrap the paint of the rack and why most telco equipment 
> frames and mounting kits are a non-painted alloy.  Data equipment isn't 
> generally made to the same standards.  So for example if you rack up a 
> 3750 you're using non-painted mounting brackets on a painted 2-post. 
> The chassis is also painted so you most likely aren't making a 
> connection between the chassis and the bracket and thus not the 2-post.
> 
> The ground in the power plane should never be connected within the 
> chassis to the chassis itself.  The power plane should never share 
> anything common with the chassis.  The chassis should always be grounded 
> separately.  Now beyond the panel at the site ground they'll likely meet 
> up again but within the powered equipment they should never touch.  Ie, 
> the ground conductor in the L5-20R that your colo provider dropped in 
> your cage should not internally connect to the chassis of the device. 
> The electronics within the device should be insulated from the chassis 
> and the chassis should have an external ground connection that you 
> connect either to the frame or to a ground bar on the frame.  Depending 
> on the equipment (thinking telco for a minute) the equipment is 
> sometimes insulated from the frame and connects to a ground bar that is 
> also insulated from the frame as well.  There are a lot of telco 
> standards out there that are meant for specific applications.  Bottom 
> line, always ground the chassis with the supplied hardware either to a 
> grounded frame or to a ground bar within the frame that goes back to a 
> site ground bar.  Not all manufacturers adhere to those standards though...
> 
> Justin
> 
> 
> Michael Ulitskiy wrote:
> > Sure, but what the proper grounding is? Does it mean that I have to run a 
> > dedicated grounding wire to every piece of equipment?
> > The racks are properly grounded (according to provider) and every server is screwed to them. 
> > The power is provided via NEMA L5-20P twisted lock connecter with proper grounding 
> > (according to provider). There I currently have tripp lites followed by managed APC PDUs.
> > All equipment is plugged in into APC grounded outlet. Does it not qualify for "proper grounding"?
> > 
> > I also personally went there with a voltmeter and check for voltage between metal parts 
> > per Seth Mattinen suggestion and I found 0 voltage. This may sound silly, but I'm taking any chances.
> > What else I can do?
> 
>