DIY project, Electrical question

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Old 09-17-19, 12:16 PM
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DIY project, Electrical question

So, I'm under an NDA for this project, so any details I can provide, legally, I will. However, I'm the electrical designer, but I'm stumped on this part of the build.
I'm bringing in 120v from the wall through a 3-prong IEC (schurter style, i suppose its called?). Now, I know the wiring system there, and running it to a 3-wire component. Everything is rated for 250v 10A, so no worries for faults here.
My question is: the 3-wire component is running to 5 laptop transformers (not exactly laptop transformers, but same design/form factors/etc). These transformers only have 2 connections, hot and neutral, no grounds. Where would you folks recommend putting the ground? Can it be capped off and untouched?
 
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Old 09-17-19, 12:24 PM
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Welcome to the forum.
250V?
What country are you working in? Sounds like it's a 50hz system you are playing with.
 
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Old 09-17-19, 12:27 PM
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Thanks.
And working in the USA, its a 60Hz system. I went with 250V rated, just to be cautious as this is a prototype build. I'm not actually pulling 250V.
 
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Old 09-17-19, 12:36 PM
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If the receptacle is three prong you connect to the receptacle.
If the box is metal you also connect to the box.
If it is direct wire to the charger then you connect to metal box and cap off ground.
 
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Old 09-17-19, 12:38 PM
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I worked on design systems for many countries despite being in North America.

When designing, you want a +/- 5-10%, more so depending on location and environment.
Most of my work (as with most stuff out there) operates at a lower voltage, allowing to clip out the inconsistencies.

Back on topic,
You are going to want to run 4 prong plug if not hard wiring and one rated for the specific current requirements. This will give you your A and B phase, natural and ground.
It will also prevent someone from plugging this into the wrong power source and cooking something or worse, killing someone.
 
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Old 09-17-19, 12:42 PM
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If the receptacle is three prong you connect to the receptacle.
it's 3 prong from recepticle to the power intake (?) for the project.
If the box is metal you also connect to the box.
it's not, it's prototype, so plastic
If it is direct wire to the charger then you connect to metal box and cap off ground.
it's going from Schurter, to wind generator.... thing... (rotates and keeps the wiring in line, i forget the name), to transformers which are going to be directly connected to the rotator i mention.
 
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Old 09-17-19, 12:45 PM
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I worked on design systems for many countries despite being in North America.

When designing, you want a +/- 5-10%, more so depending on location and environment.
Most of my work (as with most stuff out there) operates at a lower voltage, allowing to clip out the inconsistencies.

Back on topic,
You are going to want to run 4 prong plug if not hard wiring and one rated for the specific current requirements. This will give you your A and B phase, natural and ground.
It will also prevent someone from plugging this into the wrong power source and cooking something or worse, killing someone.
I'm not familiar with 4-prong plugs. We're building this for general use, plug into an outlet and let run. I'm mostly trying to identify how to manage this presently-unused ground wire.
 
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Old 09-17-19, 12:49 PM
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From what i'm gathering, i should add a layer of metal, and create a ground between that, my transformers and rotational point, and the outlet using the ground line coming in. Sounds correct?
I suppose i'm basing this on the fact that most laptop connectors don't utilize the ground plug, and simply rely on the "1-way in" method of their plug design. I'm following that principle, and utilized the Schurter design to prevent wrong direction plug-ins. Now I've put myself in the pickle with the non-used ground line lol
 
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Old 09-17-19, 06:10 PM
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The simple answer is if there is any metal in your project it should be connected to the ground wire of the cord. If there is no metal, or it is double insulated, you could just use 2 prong (ungrounded) cord. Many laptop power supplies use two-prong cords.
 
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Old 09-18-19, 05:23 AM
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1) Grounding is a protection, an I would recommend to have it!
2) Wiring sized for an amp rate at 250v will often have to high voltage drop at 120v. Be accurate when you calculate this.
 
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Old 09-18-19, 09:35 AM
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The simple answer is if there is any metal in your project it should be connected to the ground wire of the cord. If there is no metal, or it is double insulated, you could just use 2 prong (ungrounded) cord. Many laptop power supplies use two-prong cords.
Right, so i'm thinking since I have the ground line already, i'll secure it off and leave it unused for this prototype, then for future builds i'll incorporate it for customer safety.
1) Grounding is a protection, an I would recommend to have it!
2) Wiring sized for an amp rate at 250v will often have to high voltage drop at 120v. Be accurate when you calculate this.
You're right. I'd like to incorporate it, however the power inverters, i think they're known as, don't utilize the ground line, and rely on internal short protection, so I'll follow that for now and change design for later.

Thanks for the responses folks! I'll definitely be around more as my focus is low-voltage, and I'll provide my help when I can as well.
 
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