Why terminal blocks between switch panel and devices?

[sailingunity]

I was looking at Jedi's new electrical panel photos and got me thinking it seems like most builders use finger ducting and DIN rail as well for the last stop between devices and the breaker / switch panel.

On my boat the wires are led straight from the related devices to the breaker panel. Is there a good reason to go through a DIN terminal (or terminal block in general)?

I'm going to be re-vamping my engine room this year when the engine is out, and Jedi's setup makes me drool.

[SY Harmony]

I prefer the way your boat builder did it. Less connections and possible failure/corrosion points.
That said, i have a terminal strip to distribute power to my electronics components on the same breaker.

[sailingunity]

Fewer connections was my thought too, however I was thinking of voltage drop.

Also have to consider space. It could wind up looking even more busy if I try to cram a lot of components in there.

[Jammer]

Maybe.


It's based on a structural cabling mindset. The idea is that the cabling exists as a resource that can serve various purposes that may evolve over time. As such it is permanently terminated at junction blocks from which tie wires connect it to whatever equipment it serves in the moment. Western Electric started it with their standard central switching office designs in the 1920s (or before) and it has become a standard industrial wiring practice since then, with many intermediate steps.


I myself follow a strategy of solving the presenting problem rather than compromising cost and reliability today for some hypothetical future that is difficult to anticipate and which many never come to pass.

[sailingunity]

Originally Posted by Jammer

Maybe.


It's based on a structural cabling mindset. The idea is that the cabling exists as a resource that can serve various purposes that may evolve over time. As such it is permanently terminated at junction blocks from which tie wires connect it to whatever equipment it serves in the moment. Western Electric started it with their standard central switching office designs in the 1920s (or before) and it has become a standard industrial wiring practice since then, with many intermediate steps.


I myself follow a strategy of solving the presenting problem rather than compromising cost and reliability today for some hypothetical future that is difficult to anticipate and which many never come to pass.

Interesting and good to know. I guess you stand on the "wire it straight to the switch" side?

From an engineering perspective, it seems like the 'right thing to do", and the installs I've seen using DIN rail are beautiful, but I just don't see how adding another break in the wire adds anything substantial to the install, which is why I'm asking here if anyone can shed more light on it. If I'm installing new hardware somewhere, I'm going to run new wire or re-use the existing wire anyway.

I suppose one reason I can think of is that it might make wiring a little easier in the future if the spaces around the panel are particularly tight, as you would only need to run wire to the terminal.

[mvweebles]

Using a backplane - terminal strips on a breadboard - allows the bulk of the panel to be built on a bench and end product is better organized wiring that is clearly labeled - for troubleshooting, a lot to be said by seeing all the connections labeled when panel is open. Sure there is an extra set of connections but they are well supported without tension on the breakers.

Jedi's work is DaVinchi level work. Absolutely gorgeous. Mine? Maybe a 6 or 7 out of 10. Pretty good and achievable.

[blubaju]

The owner loves it for the sheer beauty, the installer loves it for earning more money, the surveyor loves it as it looks so good, cannot be wrong. So, all are happy, where is the problem? I am thinking, what is not there can not cause a problem. Switch to appliance.

[SY Harmony]

Originally Posted by blubaju

The owner loves it for the sheer beauty, the installer loves it for earning more money, the surveyor loves it as it looks so good, cannot be wrong. So, all are happy, where is the problem? I am thinking, what is not there can not cause a problem. Switch to appliance.

And some boat builders love it because it cuts production time, by utilizing subassemblies.

[s/v Jedi]

For me, the main reason is to switch wire gauge. For example, my 15A DC breakers will be wired with AWG 12 to the terminal block. The electric toilets get AWG 8 wiring to that terminal block.
I don’t want to deal with AWG 8 wiring at the breakers for 15A circuits…

Second reason is wiring density. At the switch/breaker panels, wiring is very dense and difficult to work with. At the terminal block it is much easier and this allows enough room for the bigger diameter wiring.

I just finished all the wiring for the small switches behind the main DC panel. The number of wires you deal with is unbelievable. I could make it look much nicer but don’t have the time for it

[phorvati]

This is more of a side note, but i bought Flir USB thermal camera that you plug into your phone. Its very usefull on the boat that has complex systems. Any reaistance buildup in terminals, inadequate wire gauge, old breaker with pitted contacts, all that dissipates heat and camera shows it very well.

[sailingunity]

All very good and convincing arguments! I especially appreciate the ones about pre-building as much as possible before going into the boat, and the wire gauge as well. Mine is a literal rats nest and part of the issue is it's difficult to get large wires (for the electric head, for example) routed and onto those small terminals.

[s/v Jedi]

Originally Posted by sailingunity

All very good and convincing arguments! I especially appreciate the ones about pre-building as much as possible before going into the boat, and the wire gauge as well. Mine is a literal rats nest and part of the issue is it's difficult to get large wires (for the electric head, for example) routed and onto those small terminals.

My initial plan was to first wire the individual panels with all the on-panel connections, then mount them in the console and wire all that up, then mount it in the boat. Problem is the weight, I’m not gonna get that in place without damaging something, so the console will go in without panels and wiring. After being fully mounted, I’ll add the panels and wiring from panels to busbars and terminal block.

Luckily with the new setup I can just stand in front and work right in front of me, instead of folding my legs while laying on the floor trying to see the terminals

[Jammer]

I think you'd be better off with connectors if the goal is to assemble the panels and install them once complete. There are panel mount connectors with screw terminals. Phoenix Contact has them. Their largest ones are rated at 57 amps per pin and take wire up to 6 AWG:



https://media.digikey.com/pdf/Data%2...gh%20Plugs.pdf


There are smaller versions of the same thing, and all kinds of other designs.

[sailingunity]

Originally Posted by s/v Jedi

For me, the main reason is to switch wire gauge. For example, my 15A DC breakers will be wired with AWG 12 to the terminal block. The electric toilets get AWG 8 wiring to that terminal block.
I don’t want to deal with AWG 8 wiring at the breakers for 15A circuits…

Second reason is wiring density. At the switch/breaker panels, wiring is very dense and difficult to work with. At the terminal block it is much easier and this allows enough room for the bigger diameter wiring.

I just finished all the wiring for the small switches behind the main DC panel. The number of wires you deal with is unbelievable. I could make it look much nicer but don’t have the time for it

Curious, Jedi, you look like you're going to have battery monitors on all of your banks. Do you have separate negative busses / shunts for all of those?

[team karst]

Originally Posted by Jammer

…..As such it is permanently terminated at junction blocks from which tie wires connect it to whatever equipment it serves ..,,

Ah, you mean like home wall receptacles or subpanel feeders? [emoji41]