MCA
Carpal Tunnel
Reged: 03/09/06
Posts: 2609
Loc: Illinois
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Thanks for the explaination. I never seen one of these set-ups before.
As far as the NEC, since flexibility is required and the cord does not go inside a wall it sounds like it fits one of the "where permitted" catagories.
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Gizmologist09
enthusiast
Reged: 02/08/09
Posts: 269
Loc: Palmdale, California USA
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Just to clarify, there is no movement of the screen can itself. The motor is housed inside one end of the fabric roller. The only concern about movement is basically an NEC rule about flexible cordage or flex conduit run to any device that is not rigidly mounted. Some screens are suspended from eyes in either end of the can but that is just for ease of install. Once hung, there is no movement of the assembly.
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peleliu
journeyman
Reged: 01/05/08
Posts: 82
Loc: Winston-Salem, NC
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This has been an interesting discussion. I am putting a DA-LITE screen in my basement and haven't been able to figure out how to make the connection to the jbox next to the screen.
Quote:
Although it is permissible to surface mount the SJO cord to enter a surface mount switchbox, it is rarely done as it looks terrible in most circumstances.
When you say surface mount the cord to enter a surface mount switch box are you referring to an in-wall jbox? What method is used to terminate the SJO cord into the box?
Quote:
At no time is it permissible to use a 4 conductor AC plug or 2 standard AC plugs to terminate the control harness as this would entail having switched outlet(s).
In this application is a switched outlet against the NEC? Aren't switched outlets commonly used to control table lamps?
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MCA
Carpal Tunnel
Reged: 03/09/06
Posts: 2609
Loc: Illinois
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Quote:
In this application is a switched outlet against the NEC? Aren't switched outlets commonly used to control table lamps?
It appears that you need a 4 wire cord with 2 hots. One hot to control up and one hot to control down. All wires need to be in the same cable or cord. Having the 4 wire cord rigged with 2 plugs and 2 switched receptacles will be a problem, since one cord will not have a neutral, and if one cord is unplugged when the other cord is in use then there can be back-feed current going out the other plug and will be dangerous if someone touched the plug. If it was to be plug connected then you need a 4 wire plug, but the 4 wire plugs are designed for different purposes (120/240 volt applications, 3 phase applications, etc.) and not for having the 2 different hots for motor control purposes.
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peleliu
journeyman
Reged: 01/05/08
Posts: 82
Loc: Winston-Salem, NC
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Quote:
If it was to be plug connected then you need a 4 wire plug, but the 4 wire plugs are designed for different purposes (120/240 volt applications, 3 phase applications, etc.) and not for having the 2 different hots for motor control purposes.
Yes this is the problem I am running into. But how do the professional screen installers do it? If there is no suitable plug how can the SJO cord be run into the in-wall jbox beside the screen and still look good? Is there a plastic jbox cover plate that has a hole in it that would allow the SJO cord to go into the jbox? And what method can I use to strain relief the cord? A cable clamp into the sheetrock? I am trying to make this as attractive as possible.
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Gizmologist09
enthusiast
Reged: 02/08/09
Posts: 269
Loc: Palmdale, California USA
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Most installation of electric screens has a cornice built around the can to dress the installation up a bit.
The electrical cords are naturally concealed. All you need to do if there is no cornice around your screen is to get a blank cover and carefully drill a hole for a cable clamp.
Can you post a pic of your install as I am having a hard time understanding with this is so difficult. We do this all the time ad it is quite simple.
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peleliu
journeyman
Reged: 01/05/08
Posts: 82
Loc: Winston-Salem, NC
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Quote:
Most installation of electric screens has a cornice built around the can to dress the installation up a bit.
The electrical cords are naturally concealed. All you need to do if there is no cornice around your screen is to get a blank cover and carefully drill a hole for a cable clamp.
Thanks, since I haven't seen any screen installations I didn't know how it is done. This is exactly what I wanted know.
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3phase
Electrician
Reged: 09/09/02
Posts: 6673
Loc: Licensed Electrical Contractor...
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Thanks gizmo. Never hurts to learn from the pro in his field.
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Rule of thumb,Keep your thumb from under the hammer!
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