How many wires can you connect to a mean well wire terminal? - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: March 20, 2021, 01:40:42 am
content: I ordered a replacement power supply for the Tandy 1000 one I couldn't fix - a mean well RT85B. Why they only put one common terminal on it I do not know, but I've got eight ground wires, five 5V wires, three 12V wires, and one -12V wire.

author: Jwillis
author_rank: Super Contributor
timestamp: March 20, 2021, 03:16:17 am
content: Ya that can be an inconvenience. The only thing I could suggest is an Insulated Busbar Terminal if you have the room to do so.

author: tonyh88
author_rank: Regular Contributor
timestamp: March 20, 2021, 03:33:00 am
content: Yes this is a bit annoying but you can always splice multiple wires down to one wire to then connect to your PSU screw terminal.Just make sure the wire can handle the sum of all the currents.To splice you can use bus bars, insulated wire crimp nuts, wago style connetors, soldering with heatshrink, crimped splice etc...

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 20, 2021, 03:53:08 am
content: Longer screws and spacers. Stack up the terminals, two at time, spacer, two more terminals, another spacer. Eight wires on one screw, no problem.Another possibility. Unsolder the block from the junk supply. Solder stranded wires of appropriate gauge to the block solder ends and tie the commons together with soldered on wires. Put crimp lugs on the other end, attach to new supply.Or, as already suggested: As the new supply is no doubt smaller than the original, there should be room for a terminal block with the appropriate number of screws. Make the common jumpers or buy them.

author: alank2
author_rank: Super Contributor
timestamp: March 20, 2021, 01:39:26 pm
content: Thanks guys, lots of good ideas here. WattsThat tell me about the spacer? Is this just a regular washer or something square? Maybe I need to find another terminal block and get its clamp.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 20, 2021, 01:48:52 pm
content: Quote from: alank2 on March 20, 2021, 01:40:42 amDon't overload the terminal, just splice all of the ground wires together along with a short wire stub and connect the other end of the stub to the ground terminal. Repeat for the power wires, etc.I know it's not exactly the same situation but this is the procedure that's called for in the NEC when you need to connect more than one wire to a circuit breaker in a CB panel. Per the NEC you are absolutely not allowed to attach more than one wire to a CB that isn't designed and marked to handle more than one wire.

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 20, 2021, 02:43:43 pm
content: good grief, why would you drag the NEC into this? It is a code that doesn’t understand anything less than 14 gauge wire and 15 amps. Putting a pigtail on four wires and landing it on one screw does not change the current through the terminal. The NEC is designed for trained monkeys to wire shit without burning down houses. Seriously flawed argument.The designers of the power supply provided one terminal. It underwent UL inspection. I think a barrier strip can handle the load.OP: here’s a spacer. Assumes the usual #6-32 screws.https://www.digikey.com/en/products/detail/keystone-electronics/3403/303830Stacked up washers can do in a pinch.

author: wizard69
author_rank: Super Contributor
timestamp: March 21, 2021, 12:12:18 am
content: Quote from: WattsThat on March 20, 2021, 02:43:43 pmThat simply isn't true.QuoteWell in some cases those electricians are trained monkeys but that is not the entire industry. More importantly the NEC reflects knowledge gained through research and at times the school of hard knocks. The regs may sound silly at first blush but they are there for a reason.Quote