Power Pole Power Distribution Box and Voltmeter - 5 circuit output

This distribution buss for electronic bench and ham radio use takes 1 fused input from a power supply and sends it out to 5 separate fused circuits.  I design the buss bar to be a 3/8 OD copper tube that is inexpensive or even as I had one in my scrap bucket.  I have also included a drill guide to drill the copper tubing.  

This model top and bottom blocks is based on my power supply distribution blocks.  It is not designed for high amp loads but to have a 20 amp max surge load and approximately 15 amp continuous load if built with 14 gauge fine stranded wire.  The buss bar is used with the drill guide to drill the holes for the wires to be soldered into.  The holes in the guide are undersized as I used 14 gauge wire but if you use less with a down grade in ampacity you can pick the drill size that corresponds.  Just drill the guide to the correct size before drilling the copper tube itself.  I when loading the copper tube I marked a line down the center and placed it pointing up with one side of the tube sticking out 1/8" (~3mm).  After drilling the holes from both sides I released the pressure from the screws and slid the tube 1/8" out the other side keeping the aforementioned mark at the 12 o' clock position.  an additional smaller hole is drilled for a 18 gauge wire 90 degrees  for a tap for the 12V digital volt meter.  Because a the high mass of the copper tube a used a mini butane torch to do the soldering.  

All the 4.4mm holes get an M3 heat set insert  I sized and used these but I am sure that some others will fit, all of the insert locations are 5mm deep minimum.  TIP, after setting the insert use a smooth metal block to push the molten plastic surrounding the insert and the insert itself flat and smooth immediately.  This will eliminate using a knife/wood chisel and sanding to have gap free mating surfaces.  

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The small buss retainers get an m3 insert as well and M3 screws from outside hold the retainers in place after the tube sets in the pocket.  Note that the retainers have a radiused side, that is the side that the insert is placed into and goes towards the wall of the case.  Install proper length screws so they don't hang out past the flat side of the retainer and are close to the buss risking being energized.  

Also note that the buss bars with off set go in a specific way.  As you look down from the front the wire coming from the positive buss should be to the going to the right side of each fuse terminal and the negative buss wire to the right side anderson power pole/black connector.  Length from the left wire/fuse terminal to red power pole is super critical.  I recommend crimping on the 30 amp power pole terminal, inserting it into the shell that is also placed into the bottom case, and setting the female spade terminal in its proper place to measure and cut the wire to length.  A fraction to short will not work.  I used Thomas and Betts 14-16 gauge female spade terminals with the insulating collar removed and an actual good uninsulated terminal crimper that uses a proper die not one of the cheap stamped steel crimpers that more crushes the terminal than forming a proper crimp.  I did need to tweak the post crimp terminal slightly as its a tight fit where it snaps into.  This tight fit is necessary to keep the terminal in place to interface properly with the fuse inserted into a pair of them. This picture is from the power supply but it wiring is identical in the fuse/powerpole case sections.  I would imagine that you could also stack these if you wanted more circuits with longer screws but the space would become very tight.  

This uses ATC fuses.  Since I use this block to only power accessories such as a SWR back light, antenna switches, ect I have a 10 amp fuse in and under 5 amp fuse out depending on device.  Any spot may be used as an input as long as it is fused correctly.  I use the two other fused outputs on the power the higher watt loads of the main radios.  

Voltmeter I used

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