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I'd like to hear from the electricians out there.
w ww.instructables.com/id/Web-Controlled-8-Channel-Powerstrip/?ALLSTEPS
D
w ww.instructables.com/id/Web-Controlled-8-Channel-Powerstrip/?ALLSTEPS
D
Is this great Instructables project safe?
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What the guy does on the insides theoretically may be O.K., but the box is all wood. If the box were metal or PVC, it would probably be fine for a home project. Also be aware that though there appear to be eight separate receptacles, they are all on the same circuit. The load would still be limited to a single circuit.
I cannot speak to the electronics; I have no experience with those devices. I didn't research the components for this reply.
I cannot speak to the electronics; I have no experience with those devices. I didn't research the components for this reply.
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Thank you for the response, al_smelter. I see. So the single circuit can handle 20 Amps, correct? Would that be enough to power 4 of these fluorescent lamps?
Using these ballasts
I could pare it down to four receptacles.
Here's a clickable link to the page:
www.instructables.com/id/Web-Controlled-8-Channel-Powerstrip/?ALLSTEPS
These sorts of projects are not covered by any enforceable codes or standards. It's not premises wiring, so the NEC doesn't apply. UL, ETL, and other private testing organizations only deal with products in commerce, not one-off devices made for your own use. You can make whatever you want for fun, safe or not. It's a free country!
The only major red flag I see for safety is the lack of grounding. You really need to connect all the ground terminals of the receptacles to the incoming grounding wire of the cord. With that said, I've been building stuff like that my whole life and I can see a few things I'd do differently. I don't think there's anything super dangerous about it as-is, but it's not assembled the way someone would likely choose to assemble it if they had much experience with this kind of wiring. These are the changes I'd make:
1: Don't use the back-stab holes on the receptacles. Get high quality receptacles with back-wired screw terminals, not spring loaded back-stab holes. Those are notoriously unreliable. It is an NEC violation to use them to pass a neutral connection through a receptacle as shown here. It's hardly any more difficult to do it the right way using nice stranded wire and good screw-down connections.
2: Use larger wire for all power connections. In applications like this, it is common to use much smaller wire for a given amperage than would be used in wiring a building. That's fine, but don't take it too far. Those are 10A relays, and #18 is pretty light for that. Even #16 would probably be fine. Remember that you may have this plugged into a 20A circuit, but you are limited to 10A per receptacle by the relay ratings and you may be limited to less than 20A total by the choice of cord and internal wiring that you use.
3: Do a better job handling the connections to the relays. All those orange wires are a mess, and unnecessary. I'd take a single piece of #14 or #16 stranded wire, and strip a 1/2" section every 3", in 7 places. Fold each stripped section in half, and insert into the relay terminals. Connect one end to the last relay, and the other end to your incoming power. Now you have a single wire connecting one terminal of each relay together to supply power. Much cleaner.
4: I would assemble the whole thing in a better enclosure. A Cantex box is cheap, tough, and available at Lowes or Home Depot. A purpose-built electronic enclosure might provide more options for internal mounting of the electronics, but at a higher price and you'd have to order it.
5: I would consider using solid-state relays instead of mechanical ones. It's an upgrade. It adds the requirement of dealing with cooling, but they last much longer and are silent.
6: Pay attention to the comments section on that Instructables post. There seem to be some issues on the software and digital hardware side of things, which I did not address at all.
www.instructables.com/id/Web-Controlled-8-Channel-Powerstrip/?ALLSTEPS
These sorts of projects are not covered by any enforceable codes or standards. It's not premises wiring, so the NEC doesn't apply. UL, ETL, and other private testing organizations only deal with products in commerce, not one-off devices made for your own use. You can make whatever you want for fun, safe or not. It's a free country!
The only major red flag I see for safety is the lack of grounding. You really need to connect all the ground terminals of the receptacles to the incoming grounding wire of the cord. With that said, I've been building stuff like that my whole life and I can see a few things I'd do differently. I don't think there's anything super dangerous about it as-is, but it's not assembled the way someone would likely choose to assemble it if they had much experience with this kind of wiring. These are the changes I'd make:
1: Don't use the back-stab holes on the receptacles. Get high quality receptacles with back-wired screw terminals, not spring loaded back-stab holes. Those are notoriously unreliable. It is an NEC violation to use them to pass a neutral connection through a receptacle as shown here. It's hardly any more difficult to do it the right way using nice stranded wire and good screw-down connections.
2: Use larger wire for all power connections. In applications like this, it is common to use much smaller wire for a given amperage than would be used in wiring a building. That's fine, but don't take it too far. Those are 10A relays, and #18 is pretty light for that. Even #16 would probably be fine. Remember that you may have this plugged into a 20A circuit, but you are limited to 10A per receptacle by the relay ratings and you may be limited to less than 20A total by the choice of cord and internal wiring that you use.
3: Do a better job handling the connections to the relays. All those orange wires are a mess, and unnecessary. I'd take a single piece of #14 or #16 stranded wire, and strip a 1/2" section every 3", in 7 places. Fold each stripped section in half, and insert into the relay terminals. Connect one end to the last relay, and the other end to your incoming power. Now you have a single wire connecting one terminal of each relay together to supply power. Much cleaner.
4: I would assemble the whole thing in a better enclosure. A Cantex box is cheap, tough, and available at Lowes or Home Depot. A purpose-built electronic enclosure might provide more options for internal mounting of the electronics, but at a higher price and you'd have to order it.
5: I would consider using solid-state relays instead of mechanical ones. It's an upgrade. It adds the requirement of dealing with cooling, but they last much longer and are silent.
6: Pay attention to the comments section on that Instructables post. There seem to be some issues on the software and digital hardware side of things, which I did not address at all.
Are those four lamps all you're trying to control here? If so, it would be way easier to just install an individual relay in each light fixture and run low voltage wire to the Raspberry Pi. Forget the whole receptacle-box-thingy.
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ok so power wise there won't be an overload with four lamps. Now it is a matter of figuring out how to connect the ceiling light fixture to a wall socket. What do I do about grounding???
disclaimer -> I'm not an electrician, but I've built plenty of similar things using Arduino and Pi boards.
Couple of things I would do differently:
Use real wire! Small 50ft spools of 14 AWG THHN wire are $7.50 each at Lowes / Home Depot. Get a spool of white, green and black.
Search eBay for "cord strain relief" and get one for where your power cord enters the box. The instructions call for using electrical tape, but you really want something to prevent the cord from being pulled out of the box.
Personally I'm not a big fan of wiring the neutrals and ground in series. It make for a condition where a single loose connection could result in the loss of ground / neutral for all downstream outlets.
Couple of things I would do differently:
Use real wire! Small 50ft spools of 14 AWG THHN wire are $7.50 each at Lowes / Home Depot. Get a spool of white, green and black.
Search eBay for "cord strain relief" and get one for where your power cord enters the box. The instructions call for using electrical tape, but you really want something to prevent the cord from being pulled out of the box.
Personally I'm not a big fan of wiring the neutrals and ground in series. It make for a condition where a single loose connection could result in the loss of ground / neutral for all downstream outlets.
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WOW mpoulton! Thank you for those 6 pointers. If I go the powerstrip direction I will institute those upgrades. I do like the idea of the powerstrip if not for this project but for another.
However, your idea to place the relay directly in the fixtures is phenomenal. There is even a thick gutter in between to house the relays. It will get very hot though. Would that be a fire hazard?
One thing that still confounds me is, let's say I do place the relay in the fixture casing next to the ballast. I have the HOT ballast wire to power in on the relay, and normally open on relay to the neutral wire of the ballast. If this is to be connected via a standard power cable to a wall socket, how do I ground it. Where does the GND wire on the power cord go? I ask because this is a ceiling fixture that is meant to be hard wired but is being re-purposed for a microgreens raised bed.
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However, your idea to place the relay directly in the fixtures is phenomenal. There is even a thick gutter in between to house the relays. It will get very hot though. Would that be a fire hazard?
One thing that still confounds me is, let's say I do place the relay in the fixture casing next to the ballast. I have the HOT ballast wire to power in on the relay, and normally open on relay to the neutral wire of the ballast. If this is to be connected via a standard power cable to a wall socket, how do I ground it. Where does the GND wire on the power cord go? I ask because this is a ceiling fixture that is meant to be hard wired but is being re-purposed for a microgreens raised bed.
All exposed metal parts need to be connected to the ground wire of your power cord. Connect the cord's green wire to the chassis of the fixtures.
The heat of the ballasts shouldn't be a problem for relays that are reasonably oversized. Solid-state will be easiest for sure.
The heat of the ballasts shouldn't be a problem for relays that are reasonably oversized. Solid-state will be easiest for sure.
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Does this look about right?
I see about the relays. I'll start looking for a different module.
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Thanks MJenne, I will upgrade my parts list. Someone else on another forum expressed the same concern regarding the neutrals in series. I will use this first project to learn and update the design for the second flowerbed. BTW How would you connect them?
Yes, that's how you connect the ground.Does this look about right?
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I see about the relays. I'll start looking for a different module.
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