Terminal strips and power distribution - Page 1
Forum section: electronics / general

author: willhi
author_rank: Newbie
timestamp: March 11, 2015, 08:38:47 am
content: What is a good way of distributing power for say roughly 18AWG 18VAC 15A.My problem is that I'm trying to distribute power for a model train that runs on 18VAC 15A power. Sometimes there a 14AWG feeder wire needs to be split into 20 18AWG or 22AWG wires and run through switches, breakers, fuses, relays. There will be other 12VDC circuits as well split out to switches or LED lights. All going under a table that my son and I have to crawl under.The things is that I can see this developing into a real rats nest pretty quickly. I'm buying lots of barrier strips and such but was just wondering if you guys that are good with electronics have a better way. All the model train guys seem to just live with the mess. I just came across DIP rails and thought maybe that is a better way. Haven't compared the cost yet but before I went to far I just thought I'd ask what you guys do.Thanks in advance,-William

author: richms
author_rank: Contributor
timestamp: March 11, 2015, 08:58:51 am
content: Look at car audio ground blocks and stuff like that. Overkill for the size you have, but nice robust screw terminals on an insulated platform with a cover.For the positive side, there are plenty of automotive fuse blocks. You really should fuse it when you are dropping cable size unless the power supply is already protected at a current less than the smallest of your wires can take, and you are not planning on upgrading it. I use a cheap car fuse holder which takes the blade fuses on my 12v distribution. Common up one side and then each load comes off the other side of it with a 5 or 10A fuse as appropriate.

author: codeboy2k
author_rank: Super Contributor
timestamp: March 11, 2015, 01:37:19 pm
content: you can also consider a boat/rv bus bar, or make one similar to a commercial one, with just a flat bar of brass/copper/stainless steel.

author: willhi
author_rank: Newbie
timestamp: March 11, 2015, 06:52:58 pm
content: Thanks guys. I'm sort of liking the bus bar idea. Making my own might be the best option if I can find a place to buy copper bar that's about the right size. I guess I could put it in a box or something as well.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 11, 2015, 09:08:10 pm
content: If you want to talk real serious power distribution, the proper way: use wire sized for the transformer (which I presume is fused too; usually on the primary side), run that over to a distribution block / panel, and connectindividually fusedfeeders (smaller wire, fused for the ampacity) to it. Which, in turn, do the same if they feed smaller circuits, and so on.The big hazard to keep in mind is, suppose a couple of those feeder wires get crossed or shorted, and they start heating up, but it's not enough current draw to blow the main transformer fuse, and foof, there goes a fire.The North American standard is, every circuit terminates in only one or a few possible loads (lights, outlets..). The British standard is, you have a somewhat generous circuit that spans many possible loads (maybe one circuit spanning all the outlets in one or several rooms) -- with the catch that, each load is individually fused (they require line cords with fused plugs).Of course, those rules exist because mains power has more than enough current and voltage to melt wires, ignite sparks, etc. Not nearly as big a deal at this voltage, but the available power is still probably enough to pay a little mind, especially if you have a *lot* of wire to run.Fusing every little wire is probably a tedious pain, so you don't have to go that far. But it's still worth keeping that model in mind, so you can design a safe distribution network.Barrier strips, or Eurostyle terminal strips, or DIN rail clip-on types (commonly used for industrial machines), are all very popular and effective. At the low voltage, insulation, isolation and protection aren't really a big deal (it's not like you need the fully shrouded 480VAC arc-flash prevention kind), but preventing shorts due to careless screwdrivers and stuff like that would be a convenience.More tips to draw from industry -- use cable clips, cable trays or raceways to organize wires, or at least keep the mess out of the way. Panel wiring can be pretty great, you might image search some keywords for ideas.Tim

author: Paul Moir
author_rank: Frequent Contributor
timestamp: March 11, 2015, 10:34:20 pm
content: What you might not know about those DIN mount connectors is that you can get pieces that short them together called jumper bars. You can also get all sorts of various other things for them like labels, covers and endcaps. Unfortunately being "industrial", the good ones tend to be pricey (~$2-$3 each!) but you can find cheapies in the .50c range. Having the DIN rail also simplifies a lot of other things you might want to mount like fuse holders, power supplies and relays.What country are you in?

author: dom0
author_rank: Super Contributor
timestamp: March 13, 2015, 11:04:50 am
content: You can get the DIN-style things (»Klemmblock«) sometimes very cheap on eBay if you keep an eye out for old industrial wiring panels and such stuff. Bonus: You'll also get a few DIN rails for free.

author: dexters_lab
author_rank: Unknown
timestamp: March 16, 2015, 11:44:16 am
content: search for 'commoning blocks' eg:http://uk.rs-online.com/web/c/connectors/terminal-blocks-din-rail-terminals/commoning-blocks/?sra=p

author: cosmicray
author_rank: Frequent Contributor
timestamp: March 17, 2015, 12:38:15 am
content: If you have an insulated surface to mount it on (plywood, etc), a Ground Bus Bar is a handy device to connect multiple wires to, and distribute voltage. You would need one each for the positive and negative distribution.