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I have about 40 positive and 40 negative 18 gauge wires that I am trying to connect to one DC power source.

I have a few terminal blocks to achieve this. Each terminal block has 2 rows of 12 positions and I am trying to minimize the number of terminal blocks I use to wire everything together.

Below is a photo of the type of set up I am going for. My concern, however, is that stuffing too many wires into a single terminal hole is probably an unsafe practice. Is there a best practice for how many wires I can safely stuff into terminal block screw holes? I know the wires must not be tinned but is the number of wires I can fit into a terminal block hole affected by whether the wires are stranded or solid (I have both and wonder which is preferred)?

Also if anyone has a better way to wire these connections together I'm all ears, I feel like there must be a better way of doing this...

enter image description here

Matt
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  • It's datasheet would say. Commercial electric (not specifically that brand) wire nuts also say right on the retail packaging what size wire they are for and how many of a smaller wire can/should be tied together for proper electrical contact. – Passerby Aug 10 '18 at 18:53
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    @Passerby I ordered them off Alibaba and they didn't come with a datasheet unfortunately – Matt Aug 10 '18 at 18:54
  • Also carrying 10 amps on a single 18 awg pair seems hazardous. – Passerby Aug 10 '18 at 18:58
  • @Passerby good point, I'll look into that and increase wire size – Matt Aug 10 '18 at 19:03
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    If you are concerned about reliability or safety, never buy something that comes without a datasheet. – Elliot Alderson Aug 10 '18 at 19:07
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    IMO, you are using the wrong type of product. Use Barrier Strips with matching jumper strips instead. That will allow the use of crimp style spade terminals for the 18 gauge wires. You can typically get 3-4 18 gauge wires into one Spade terminal for 18-14 gauge wires. – Norm Aug 10 '18 at 19:15
  • @Passerby - I agree - 10 amps is way high. I would not do more than 1-2 amps continuously through 18g wire. OP, you should run 14g from the power supply to the distribution strips, as well as the jumper side of the strips. – Norm Aug 10 '18 at 19:18
  • Gotcha thanks guys! Quick question, how do barrier strips differ from the terminal block I'm using now? They look like the same thing when I google them. – Matt Aug 10 '18 at 19:32
  • @Passerby It completely depends on the cable type, but 18 AWG can usually [handle 10 A fine](https://www.stayonline.com/reference-circuit-ampacity.aspx), potentially [more](https://www.iewc.com/-/media/iewcglobal/files/resource-downloads/suggested-ampacities.pdf). – user71659 Aug 10 '18 at 19:59
  • Also do crimp style spade terminals prefer solid or stranded wires? – Matt Aug 10 '18 at 20:02
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    Stranded wire is better for crimp terminals if you're not soldering. I would suggest first checking out "Terminal block bus bar"s. They are simply a busbar, pre-mounted on an insulator and pre-tapped and screws provided for a number of connections. I would suggest "fanning out" the connections as well. Use the largest wire allowed to attach the DC supply to the center of the first bus bar, and large wires off of those bus bars to feed the centers of the necessary number of bars to connect all of your 18 guage wire. This will ensure they receive more balanced current. – K H Aug 10 '18 at 22:40
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    As for the terminal blocks you have, if you can figure out what material they are at least, and you find the measurements of the thinnest part of the connection, calculate it's cross sectional area and now you know what size of conductor you can consider that terminal block to be. The only question other than that is how many conductors it can effectively mechanically secure, and in practice, that typically amounts to what will fit in the hole and still allow the screw to be done up to rated torque (you don't have a datasheet, so you can use the rated torque of a screw of it's type. – K H Aug 10 '18 at 22:50
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    In practice you can typically greatly exceed this torque to little or no ill effect. After you've done up the wires in the terminal, gently-moderately pull on each one individually to ensure it is compressed by the terminal. – K H Aug 10 '18 at 22:52
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    If you have a drill and a tap and die kit, you can buy some sheet or bar copper, make yourself some insulators and custom make a busbar as well if you like. Going back to the picture you've posted, as long as you're not exceeding the ampacity of the conductor that is the terminal block, what you show should actually be OK, provided that you do it much more neatly (put in no more wires to a single terminal than you can do neatly, so that each wire goes the full length of the slot and it's insulation lines up with the others, as close to the block as possible. – K H Aug 10 '18 at 22:56
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    If this is a commercial product you want to sell, I would note that unless you get an engineer to sign off on an unrated part/part without datasheet, or you yourself are legally qualified in your region to make the distinction (electrician, EET, etc) you shouldn't use that part. In this case, having found a device with known maximum limits, you should not exceed them unless you have documents proving that you know it to be safe (get and engineer or inspector to sign off on it). – K H Aug 10 '18 at 23:00
  • they make 5 terminal level-operated wago connectors; simpler, smaller, faster, good connection, etc. a handful of those will get you right, you can put 2 18s per hole. – dandavis Aug 10 '18 at 23:08
  • @KH thank you appreciate the advice! I think Im going to get some crimp spade terminals, stranded 14 gauge wire just to be safe and busbars like shown in [this photo](https://www.12voltplanet.co.uk/150a-busbar-with-2-studs-20-screw-terminals-extra-long.html) Then I'll only attach as many spade terminals as will fit comfortably onto the bus bar. Does that sound like a good strategy to you? – Matt Aug 11 '18 at 04:54
  • That will absolutely work. If you can buy or salvage small amounts of wire and a few more grams weight isn't an issue, you may want to just use the largest wire that reasonably fits the terminal, or if they're screw through center types, you can use one wire on each side of the screw. If you can buy just a few feet, I'd grab 12 gauge or even 10 gauge stranded. Keep the wire lengths as short as practicable if you can too. That bar will totally work! If you want you can probably double stack spade terminals and only have 2 wires per spade. – K H Aug 11 '18 at 05:11
  • @Matt WHOA! I just looked at the price of those busbars! 20 L money units is like 30 or so shmeckels each, so I would seriously consider getting salvage copper and building a set. – K H Aug 11 '18 at 05:15

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You'll spend a little more, but use DIN rail mounted modular terminal blocks with jumper bars and you'll have a much nicer setup.

enter image description here

batsplatsterson
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  • A DIN rail setup might be bigger than the power supply. – D Duck Aug 11 '18 at 01:02
  • Yeah this seems like a bit overkill, I think a simple busbar will do the trick after reading the other comments. Thanks for the suggestion though! – Matt Aug 11 '18 at 04:47
  • @DDuck - Have you ever used these? With standard 5mm terminal blocks, you'd be under 6" overall. With the high density blocks with three terminals on each side, you'd be around 2" long. No doubling up. – batsplatsterson Aug 11 '18 at 11:55
  • @Matt a busbar would certainly work but terminal blocks are very flexible, easy to expand or shrink, make very secure connections without crimp on terminals on the wires. Once you use them you'll never go back. – batsplatsterson Aug 11 '18 at 11:58
  • @batsplatsterson The power supply (5-50-5 ie a 5 V 50 W supply for driving LEDs) in the photo is about 158 x 98 x 42mm, but the DIN terminals you're suggesting is about the same volume. It's obviously much bigger than the terminal strip on the power supply itself. Why not use a strip like the one on the power supply? – D Duck Aug 11 '18 at 16:01
  • @DDuck - The terminal block is easy to work with with a lot of wires in a small footprint, very solid connection without first stripping and crimping on spade terminals, most are touch safe and less prone to shorts than terminal blocks with exposed screw terminals, easy to test, easy to expand ... just generally nice to work with. – batsplatsterson Aug 12 '18 at 00:03