Sunday, September 30, 2012

A Discarded HP (Hewlett-Packard) mPDU

My boss at work found this and thought I might have use for it.

It's an HP Modular Power Distribution Unit (mPDU). Not shown in the photo are three more power bars, and a heap of steel brackets and fasteners. It's all brand new; it was in its original box.

It seems a school was throwing it out,[1] so my boss snagged it. I don't have use for the breaker/distribution box, but the power bars I can certainly make use of -- I just have to replace the peculiar plugs they have with standard ones.

The power bars' line cords exhibit something I've not seen before -- the wire gauge expressed in both American Wire Gauge (AWG) and metric. The AWG number is '14'; the metric 'gauge' is 1.5mm2. Looking up a combined AWG/metric wire gauge table reveals that 1.5mm2 is actually a bit shy of 14 AWG, so the cords are either 'light' 14 AWG, or 'heavy' 1.5mm2. It strikes me that the metric 'equivalence' figure here is at best unhelpful, at worst misleading.

Anyway, enough of that.

I picked up four Leviton No. 515PV plugs to make the power bars useable. They're the type with clamp-style terminals that I find to be easy to work with and very reliable. Here's a view of one opened up.

Installing these is a no-brainer, really, but it's nice to have predetermined dimensions for jacket and insulation strip length. I'll go with 1" for the jacket, 3/8" for the hot and neutral wires and 1/2" for the ground wire. Here's how that looks.

The colour coding is international, not North American. Here's the equivalence in the form 'Function/N.A. colour/Int'l colour'.



Ground/Green/Green with Yellow Tracer

It's easy to remember the international colours if you think of 'line' as 'hot', brown as a 'warm' colour and blue as a 'cool' colour.

I like to tin stranded conductors with 60/40 electronic solder and flux. Here's how that looks after the flux residue has been cleaned off.

Those strip length dimensions I used make for a nice, compact installation that for certain will fit the shell and the strain-relief clamp correctly, like so.

Now I've got the use of one of the four power bars; I just have to come up with a way to mount it. The mounting provision is an M5 threaded hole at each end of the bar, like so.

The brackets that came with the mPDU are all odd looking things meant for mounting the bars in an electronic equipment rack -- they're not suitable for mounting to a flat surface as I have in mind. A common one-inch corner brace may be a simple solution.

That will work, but I'll need some 1/8" thick material for shim 'washers' to take up the space under the corner braces.

A while ago, I came up with a neat method for ripping odd thicknesses of shim/spacer material on the table saw. I'll apply it here and I'll have just what I need shortly.

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And here we are.

Now I can replace this clunky old arrangement.

And here we are.

Much better. That corner brace and 1/8" shim mounting arrangement turned out well; that power bar is solidly attached to the bench leg.

By the way, having plenty of well-situated, permanently installed power bars in a workshop is a great convenience -- well worth the expense to acquire them and the work to install them. I dislike extension cords; they're a nuisance and a trip hazard. I have something like six power bars installed here and there in my shop, and they save me a lot of aggravation.

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[1] I could go off on a rant here about government waste, but that would be futile. Waste is everywhere in our economy; the economy practically runs on the production of waste. At least in this case, I was able to intercept a bit of it to my advantage. Good. And if some school wants to throw out a new milling machine and some welding gear where I can find them, that would suit me just fine.

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