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Old 09-12-2018, 10:14 PM   #21
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I just happen to have a NEMA Diagram , Device Designation and Symbols for Industrial Controls and Systems (NEMS Standards Publication ICS 19- 2002 (R2007) ).What it says that you should note what is considered normal state for the contacs and when the contacts open close .
"When it is desirable to show contacts in the energized condition or when confusion may result add a note."

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Old 09-13-2018, 02:21 PM   #22
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If you can show a diagram of where this is different, I'd be interested to see it.
I've never seen that deviation on a diagram, but that is with my experience in my area, I've come to learn that things can be different in various areas.

Even with the level switch you mentioned shown in the energized state, the symbol for that level switch would still be drawn as a NO float. It can be shown on the drawing as closed (it's normal state when full), but the symbols for NO and NC floats are different.

Yes it is drawn as a NO contact as you show. But they would just raise the float showing it closed but still under the contact. The NC contacts are shown above laying on the contacts and raised above the contacts to show the gravity position. They will do it for limit switch's, pressure and level.


I hope to post a book I wrote in the 90's on troubleshooting and print reading soon, just have to scan it into a PDF lost all the software copies I had but just found paper version.
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Old 09-13-2018, 04:22 PM   #23
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I am going thru this right now. I order a roller switch for a closet door and the info said normally closed. To me that means the contact is not engage when the button is not depressed. However, in the alarm field, as stated by Hax, it is the opposite.

Now I need to get a switch that is normally closed when the door is open. Does anyone have a source for one? This is not a line voltage switch as I have a relay
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Old 09-13-2018, 05:01 PM   #24
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I am going thru this right now. I order a roller switch for a closet door and the info said normally closed. To me that means the contact is not engage when the button is not depressed. However, in the alarm field, as stated by Hax, it is the opposite.

Now I need to get a switch that is normally closed when the door is open. Does anyone have a source for one? This is not a line voltage switch as I have a relay
Are you talking about the RIB ( relay in box ) ?
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Old 09-13-2018, 05:25 PM   #25
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Are you talking about the RIB ( relay in box ) ?
I have the relay. This is what I have but it is reversed.

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Old 09-13-2018, 11:36 PM   #26
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Quote:
Originally Posted by Dennis Alwon View Post
I am going thru this right now. I order a roller switch for a closet door and the info said normally closed. To me that means the contact is not engage when the button is not depressed. However, in the alarm field, as stated by Hax, it is the opposite.

Now I need to get a switch that is normally closed when the door is open. Does anyone have a source for one? This is not a line voltage switch as I have a relay
This site has both N/O and N/C but they are 12 volt.

http://www.elecdirect.com/cole-herse...CABEgKG1PD_BwE


Just like a refrigerator!

https://www.smarthome.com/electric-d...SABEgL21PD_BwE


For a real treat, check out the top of the screen at 6:18.

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Old 09-14-2018, 09:50 AM   #27
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Quote:
Originally Posted by Dennis Alwon View Post
I am going thru this right now. I order a roller switch for a closet door and the info said normally closed. To me that means the contact is not engage when the button is not depressed. However, in the alarm field, as stated by Hax, it is the opposite.

Now I need to get a switch that is normally closed when the door is open. Does anyone have a source for one? This is not a line voltage switch as I have a relay
I would say that is normal logic. NC, The switch is closed 'when it's in your hand'.

Switch here https://www.morrisproducts.com/pc_pr...8166F4C3E05E98

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Old 09-14-2018, 09:54 AM   #28
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Yes it is drawn as a NO contact as you show. But they would just raise the float showing it closed but still under the contact. The NC contacts are shown above laying on the contacts and raised above the contacts to show the gravity position. They will do it for limit switch's, pressure and level.
Yes, because those devices have 2 different symbols. It's obvious if it is NC or NO. (like the float symbols I posted)
I was under the impression that someone saw a contact shown in it's energized state, which I have never seen.
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Old 09-14-2018, 10:17 AM   #29
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Quote:
Originally Posted by emtnut View Post
I would say that is normal logic. NC, The switch is closed 'when it's in your hand'.

Switch here https://www.morrisproducts.com/pc_pr...8166F4C3E05E98

#70332
Yeah, that is just like the edwards one I just ordered -- Thanks. I wanted one in white but what the heck. Next time they are getting a line voltage one and screw all this crap.
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Old 09-14-2018, 11:08 AM   #30
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I'm not an alarm guy, but in any safety process we would use NC contacts that would open on alarm. That way if a contact rusts out, or something eats the wiring, you get an alarm.
n/c with magnet attached to reed switch. in hand without magnet n/o. Door closed Roller ball depressed door closed sw is closed. All these switches are available n/c n/o or s.p.s.t. GRI is one manufacturer.

Last edited by batwing44; 09-14-2018 at 11:25 AM. Reason: add info
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Old 09-14-2018, 12:05 PM   #31
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Yeah, that is just like the edwards one I just ordered -- Thanks. I wanted one in white but what the heck. Next time they are getting a line voltage one and screw all this crap.
Agreed. This is WAY too complicated.
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Old 09-14-2018, 04:42 PM   #32
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Agreed. This is WAY too complicated.
Not so complicated but it can be difficult to implement based on the light fixture etc. Then customers complain that the strike is not white even though you only see it when the door is open. One wants brass, another white or stainless... I say screw it again
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Old 09-14-2018, 04:49 PM   #33
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Not so complicated but it can be difficult to implement based on the light fixture etc. Then customers complain that the strike is not white even though you only see it when the door is open. One wants brass, another white or stainless... I say screw it again
Just flip it using a relay. Thats what we do in a pinch with industrial stuff
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Old 09-14-2018, 05:33 PM   #34
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I just ran into this doing a fire alarm job. Depends on where the relay was built but normally closed was open untill it was energized.....i was doing duct dectors. A few schools called wondering why there AC wasnt working.....they hadn't energized the FA panel yet so to all the duct unit shutdowns had no power
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Old 09-14-2018, 05:59 PM   #35
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I just ran into this doing a fire alarm job. Depends on where the relay was built but normally closed was open untill it was energized.....i was doing duct dectors. A few schools called wondering why there AC wasnt working.....they hadn't energized the FA panel yet so to all the duct unit shutdowns had no power
That is a normal occurrence. Duct detectors are their own special breed. Some run off the FA power, some run off the HVAC unit power. Some aren't even hooked up and I think it is mostly because of this situation you have posted.

FA installers think the HVAC, electric sub, GC, will hook it up for their final but don't. Then it is next year and the FA inspection rolls around and ooops! No HVAC shutdown.
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Old 09-14-2018, 07:50 PM   #36
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I thought the NEMA definition said "with no external forces acting on the device". So, no push, no pull, no power.
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Old 09-15-2018, 12:13 AM   #37
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I thought the NEMA definition said "with no external forces acting on the device". So, no push, no pull, no power.

No, it's....
"No shoes, no shirt, no service"!
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Old 09-15-2018, 08:51 AM   #38
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No, it's....
"No shoes, no shirt, no service"!
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Old 09-15-2018, 09:16 AM   #39
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As to the OP’s question, it is in the de-energized state IMO.


Not all fire alarm manufacturers are the same, some show NC and it is actually NO, others show NC and it is actually NC. Drives me nuts!

Like the old tamper switch on sprinkler devices. The switch required for that circuit is NOHC ( normally open, held closed) but different manufacturers show it differently in their manuals.

Another problem with FA manufacturers is how they show polarity in their manuals. Some show polarity for signals in a normal state, others show them in alarm state.

There should be a standard for all.

Last edited by eddy current; 09-15-2018 at 09:19 AM.
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Old 09-15-2018, 01:47 PM   #40
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As to the OP’s question, it is in the de-energized state IMO.


Not all fire alarm manufacturers are the same, some show NC and it is actually NO, others show NC and it is actually NC. Drives me nuts!

Like the old tamper switch on sprinkler devices. The switch required for that circuit is NOHC ( normally open, held closed) but different manufacturers show it differently in their manuals.

Another problem with FA manufacturers is how they show polarity in their manuals. Some show polarity for signals in a normal state, others show them in alarm state.

There should be a standard for all.
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