Shelly DIN Mount "Pro Upgrade"

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Design

The DIN mounts one can find for Shellys are mostly “open” designs without a proper full housing. Furthermore, they come with “open” terminals one may not want to expose in their junction / breaker box.

Designing a closed housing is a bit challenging because the Shelly Plus 1PM is 16 mm wide while a 1 TE DIN housing should be 18 mm. So we have 1 mm for each side minus some gap to allow insertion. The housing includes openings for both sides of the Shelly to allow heat dissipation.

Security

While the resulting 0.8 mm side wall thickness is not enough for puncture resistance, it is coming on top of the Shellys housing for most parts. In any case - when printing housings for electronic circuits, please use fire retardant filament. This will be some special ABS / ASA filament. In any case, use this is on your own risk!

Terminals

The terminals are the second big speciality of this design. They separate the outer wiring from Shelly wiring. The Shelly's L, N, O, and SW contacts are supported, but you may use the four terminals in any way you like.

We use screw terminals like used for electric installations of lamps etc. to implement the terminals. Please see the parameters pictures for the screw terminals used. The metal terminal itself is removed from the plastic and inserted into mounts matching the our model. 

Oddly, sizes for the screw terminals are not standardized. This 3D model collection provides a mount we have used, but you may need to adjust the model to your needs. To allow this, we provide the parametrized Fusion360 file.

Some thresholds you need to match: use terminals with M3 screws. The inner diameter of the terminal should match a single wire 10m2 - which is roughly a 3.5mm diameter. The length of the metal terminal should be 14mm max. Otherwise, wall thicknesses will be too low / negative.

Bigger sizes will not match, smaller sizes will not be strong enough for the 16 A we want to support.

Printing

Version with two screws to close the housing (recommended):

• 1 x BodyBaseWithScrews
• 1 x LidWithScrews
• 1 x TerminalMountTop
• 1 x TerminalMountBottom
• 1 x Snap

Version without screws:

• 1 x BodyBase
• 1 x Lid
• 1 x TerminalMountTop
• 1 x TerminalMountBottom
• 1 x Snap

The first version requires two M3 screws a length of roughly 9mm including head.

All parts can be printed without support. All STL models need some rotation, see the Files section for instructions. We love black filament for the Snap, and a warning color for the TerminalMounts. White or light gray for Lid and BodyBase.

Printing is done with a 0.4mm nozzle and 0.2 layer height, 15% infill.

Wiring

Internal wiring (i.e. connections from screw terminals to Shelly terminals) will require some 2.5mm2 single core wires with these lengths:

• N: blue, 32 mm
• L: black/brown, 44 mm
• O: black/brown, 32 mm 
• SW: black/brown, 36 mm

Please remove 4 to 5 mm of insulation on both ends, see picture.

Assembly

1. Disassemble the screw terminals, we need four terminals (with 8 screws)
2. Push the four terminals into the two TerminalMount parts
3. Slightly screw the four screws into the inner holes
4. Prepare all the internal wires and make sure all lengths match
5. Tightly screw the inner wires - once the terminals mounts are pushed into BodyBase, the screws are not accessible any more; moreover, the terminal mounts are hard to push out again 
6. Push the mounts into the BodyBase
7. Insert the Shelly and tighten the Shelly terminal screws
8. Slightly screw the remaining 4 terminal screws through BodyBase / TerminalMounts and terminals. This will fix the TerminalMounts inside the BodyBase.
9. Close the housing (see two versions above)

Attribution

The DIN rail snap mechanism is inspired by https://www.printables.com/model/112153-shelly-plus-1-din-rail-mount