![]() For example, if I have a string of blocks acting as neutrals that are center jumpered and I know that I will have 20 wires coming to them, do you figure 20 blocks or figure 10 blocks (plus one for the circuit neutral). Further, when counting the number of blocks for a series of blocks with the same function, do you count wire on only one side of the block. If you prefer to have each wire to its own block, do you typically use a 6mm or even a 5mm block (when dealing with nothing larger than size 14 wire)? This would seem to be the route to go as the larger blocks would only be needed for single larger wire size or a combination of two smaller wire sizes. Since power failures are very rare in this area, most people choose to assume that almost all failures are going to be dead shorts which will quickly be removed by the upstream protection, and that the risk is minimal. ![]() In theory, the vertical runs are totally unprotected if you get a short on the bus. It's the same argument you run into with MCC's and other modular power distribution systems where the horizontal runs are usually huge but the vertical runs are rated for perhaps half that much. The major disadvantage to them is that at least theoretically unless you make the wiring on both sides identical in size, it's a Code violation because the outgoing wires are not short circuit protected. If you're wiring up power circuits, you can get 3 phase distribution terminals which have say 1 or 2 large terminals on one side and as many as a dozen smaller ports on the other side. You can't get high power or fused or anything but feed-through terminals this way for the most part. The blocks from Omega are actually coming from Telemechanique and are very well built. Seems they didn't stock them and the special order took months to arrive (way beyond the stated delivery date). I have bought them from Mouser or Newark before (Phoenix Contact or Weidmuller) but I was very disappointed. ![]() They seemed to have the best price from a major vendor. I just bought the last few boxes of IDC terminal blocks from Omega. It makes vibration-proof, sealed (no oxidation) connections. They are now almost as cheap as regular terminal blocks and the wiring time is much shorter since all you have to do is cut the wire and insert it. There's no wire stripping and you flat out can't overload the terminal block because it won't work. If you want to minimize installation time and enforce the "one wire per terminal" rule, buy insulation displacement terminals. The way you make it work is by buying terminal blocks that have ports running down the center of the terminal block where you place a jumper bus bar. Putting two wires in a terminal is a Code violation unless it is specifically rated for it, in the U.S., because you are not using the device in the way it is Listed, making it an unlisted (and illegal) installation. Most terminal blocks are certified with UL for only one wire.
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