DIN rail wiring

[brewdexta]

I'm assembling my home grown underfloor heating controls and I've decide to use DIN rail to mount the kit. I have an upstairs and a downstairs installation, each has a 12v and 5v Mean Well PSU, a Raspberry Pi and an IP relay board. I will also be using DIN rail connection blocks similar to these for mains, DC and one-wire temperature sensor wiring. The 5v is for the raspberry Pi as there is likely to be more than one eventually and I hate power bricks even though the Pi has micro USB connectors for power, the 12v is for the IP relay board which will be in a DIN rail enclosure.

The PSUs need reasonable ventilation so sticking them in a box is not a good idea however the wiring is then somewhat exposed. I've looked at loads of enclosures on-line and just wondered if there is any kind of wiring convention for this kind of kit. I'm a stickler for tidy safe wiring.

Here's the PSU and Raspberry Pi (in its own DIN rail enclosure).

This is the IP relay board while I'm developing the code for it, not mounted in the box yet.

Cheers
Andy

 

[tomsutton529]

Cracking project. Nice to see a UK made micro board being used.. I've been thinking of using one to switch motors off when reach an alarm level based on the vibration levels.

 

[Luke]

Standard procedure would be to use an enclosure with a lid or door. Tradtionally steel - look at rittal, eldon, to name a few. Also GRP or ABS options are avaliable.

A steel wall mounted enclosure will typically have a separate zinc pas. steel backplate to mount DIN rail and components to, and provide good earthing. The bottom of a wall mounted enclosure will typically have a removable gland plate for you to drill and fit cable glands etc.

The skin will dissipate a certain amount of heat (given on the datasheet) and if more dissipation is required, filtered fans are a common solution and are off the shelf parts. Rittal supply their own or look at pfannenberg for example.

 

[brightspark]

if your going to use a cabinet nothing stopping u drilling some holes top and bottom or in the sides and buying some mesh grilles and fitting them

 

[brewdexta]

I can see a Rittal compact steel enclosure 500 x 500 x 200 for about 80 quid delivered. The fibreglass reinforced plastic ones seem to be a lot more, I thought they would be less so I will stick with steel. I may have a chat with our work power guys to see if they have any lying around awaiting to be skipped, hopefully

I can put a temp sensor in the case to see if I need to add more ventilation.

 

[Luke]

Rittal are probably the leading brand. We mostly use Eldon as they provide a better balance on price & quality.

 

[daleyd]

Could you add a temp sensor and relay to the pi to switch a fan on and off on demand?

With regards to the wiring there are some standards but almost every one I've worked on has something different. Normally black dark blue or pink wiring for lower voltage (24 normally in industrial stuff) and you would want normal 240 volt colours (brown and light blue) for the incoming or anything that's 240 volts. The terminal strips are generally segregated as well, to keep 240 separate from the lower voltage stuff.

 

[Luke]

If you've got a fair bit of wiring between terminals, it's worth picking up some slotted trunking to route wiring around the panel and segregate control and mains voltages.

 

[brightspark]

and make the wiring look a a lot neater and if u have a drawing of it use cable markers so at a later date u can identify the teminal ends for testing if anything goes faulty

If you've got a fair bit of wiring between terminals, it's worth picking up some slotted trunking to route wiring around the panel and segregate control and mains voltages.

 

[daleyd]

and make the wiring look a a lot neater and if u have a drawing of it use cable markers so at a later date u can identify the teminal ends for testing if anything goes faulty

^^ top advice too, I hate fault finding in panels with no wire numbers!!! (Though if it's a fairly simple system you can generally get by without).

I found the write on 3m dispenser type quite good for odd jobs, but for larger jobs I usually use a label printer. If you have a label printer already you may find it can do wire labelling.

 

[brewdexta]

Could you add a temp sensor and relay to the pi to switch a fan on and off on demand?

That's exactly what the underfloor heating project does, take temp readings from rooms and turns a relay on depending on temp setting, time of day etc. I have spare relays/sensors so not a problem

With regards to the wiring there are some standards but almost every one I've worked on has something different. Normally black dark blue or pink wiring for lower voltage (24 normally in industrial stuff) and you would want normal 240 volt colours (brown and light blue) for the incoming or anything that's 240 volts. The terminal strips are generally segregated as well, to keep 240 separate from the lower voltage stuff.

I've been using tri-rated wiring for the brewery control panel, I guess this is the right stuff.

If you've got a fair bit of wiring between terminals, it's worth picking up some slotted trunking to route wiring around the panel and segregate control and mains voltages.

I shall have a look, the downstairs enclosure will be in a tight space so possibly not very big however sounds the right way to go. Upstairs there's loads of room so I can get a bigger enclosure, however I shall see what I can scrounge form work first, beggars can't be choosers.

if u have a drawing of it use cable markers so at a later date u can identify the terminal ends for testing if anything goes faulty

Definitely, I've got a few packets of the numbered rings somewhere and a label printers etc.

 

[Robotstar5]

I've got a Himel CRN 65/250 enclosure, think it's 600 x 500 x 250mm complete with chassis plate if it's any use to you?.

 

[brewdexta]

I've got a Himel CRN 65/250 enclosure, think it's 600 x 500 x 250mm complete with chassis plate if it's any use to you?.

I'll have a measure once the kids have dropped off, they're a bit wired after being on the Santa express

I'm driving down one of our facilities Tuesday, if there is nowt there and it fits then I'm definitely interested.

Cheers
Andy

 

[brewdexta]

Result! As I thought, there was a couple of cages of recovered stuff at work from a recently vacated office that was heading to the circular filing cabinet. I managed to get two enclosures, a smaller one for under the stairs just for the PSUs and mains wiring distribution. I can keep the relays and rPi separate here as I'm challenged for space. Upstairs I have a nice 300 x 400 x 215 box with back plate and can just about get all of it in there.