axolotis
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Joined: Sat Mar 09, 2019 10:33 pm

Power for outoor enclosure

Fri Mar 15, 2019 6:20 pm

I am building a pi-based weather station. I have an outdoor weatherproof enclosure that I needs to have access to two 110V power outlets (one for the pi and another for an anemometer). What I would like to do is install an outdoor-rated surge protector (power strip) inside the enclosure with the power cord running out of the enclosure. This way only a single power cable would run out of the enclosure and multiple devices could be connected to power inside.

I have not had any luck finding examples of this. Ideally I don't want to have to drill a hole in the enclosure that is any larger than the power cord diameter. In order to accomplish that though, I would have to disconnect the power strip from the cord and reconnect it inside the enclosure. Is this common for projects like these?

Are there better commercially available solutions or popular methods for wiring power into an outdoor pi enclosure?

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Burngate
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Location: Berkshire UK Tralfamadore
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Re: Power for outoor enclosure

Fri Mar 15, 2019 7:15 pm

Although mains is less dangerous on your side of the Atlantic than on ours, I'd still be advising getting a proper electrician to help.

Yes, I've removed the cable from a power strip to install it as you want, and reattached it afterwards (actually, removed and replaced the plug from the other end), and, yes, I've run mains out into the garden for various reasons, but in doing so, there were various hoops I had to jump through to make it safe.
And not all of those hoops are obvious, until you've done some research.

Is the cable you're considering using weatherproof?
Are you going to use a proper cable-gland on the hole in the box, and will it still be weatherproof once you've cut that hole in it?

Once you've installed everything, spiders will build their webs around it, then birds will land on the cable, destroying the insulation as they peck the spiders.
Dead pigeons are the first symptoms of problems ahead.

pfletch101
Posts: 408
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Re: Power for outoor enclosure

Sat Mar 16, 2019 2:51 pm

Burngate wrote:
Fri Mar 15, 2019 7:15 pm
Although mains is less dangerous on your side of the Atlantic than on ours, I'd still be advising getting a proper electrician to help.

Yes, I've removed the cable from a power strip to install it as you want, and reattached it afterwards (actually, removed and replaced the plug from the other end), and, yes, I've run mains out into the garden for various reasons, but in doing so, there were various hoops I had to jump through to make it safe.
And not all of those hoops are obvious, until you've done some research.

Is the cable you're considering using weatherproof?
Are you going to use a proper cable-gland on the hole in the box, and will it still be weatherproof once you've cut that hole in it?

Once you've installed everything, spiders will build their webs around it, then birds will land on the cable, destroying the insulation as they peck the spiders.
Dead pigeons are the first symptoms of problems ahead.
+1

For anything except a very temporary installation, your (i.e. the OP's) power cable should be protected by conduit and/or (if appropriately rated) buried deeply enough not to be disturbed by routine gardening activities.

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NGC6543
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Joined: Thu Feb 28, 2019 7:30 pm
Location: Lancashire, UK

Re: Power for outoor enclosure

Sat Mar 16, 2019 4:31 pm

I've no idea what the electrical regulations are where you are, and whether you can be prosecuted for not following them, but in the UK we have to be careful to comply with them. That gets a little more complicated when going outdoors.

While I'm familiar with the above, and have laid armoured cable around the place, my first thought would be to avoid having to take mains voltage to your external box.

Do you really need it? Could you instead send, say, 12V or 24V to the box and have a small SMPS in the box to supply the Pi and whatever voltage your anemometer needs? Using 24V would reduce the current requirement in the supply cable so that it wouldn't have to be too thick.

This way, you get around any regulation and mains voltage safety issues. You'll still want to protect the cable from peckers and nibblers though.

Earlton2
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Re: Power for outoor enclosure

Sun Mar 17, 2019 1:49 am

I'd use a 12V line if that will power both devices with 7805 regulator to generate 5V into the Pi on the GPIO lines. There are also pin compatible switchers with the same footprint but less heat.
My set-up uses a 12V trickle charged battery to provide power for several devices scattered around the house.
To enter boxes I have often cut/melted a round hole to accept the plug and then added a wooden peg split and grooved for the wire down the middle, to fill up the hole.
For another example I use the 120VAC valves found in washing machines to run a garden watering system. I didn't want to switch and distribute that level of AC so I switch the 16VAC from our doorbell transformer and fed that to transformers inside the watering system. From there it's only 6" of 120VAC wire to the valves.

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