# EFSO switches



## 460 Delta (May 9, 2018)

I’m not sure I’m following you, but a simple series loop like an E-Stop comes to mind. 
Could you please describe the entirety of it with more detail?


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## yankeejoe1141 (Jul 26, 2013)

Sounds like you just want them in series like 460 said if you’re trying to open one circuit from two locations?


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## WronGun (Oct 18, 2013)

yankeejoe1141 said:


> Sounds like you just want them in series like 460 said if you’re trying to open one circuit from two locations?


Yes, 

There is an existing EFSO in place. 

We need to add an additional EFSO to the same circuit.

They are both normally closed, but they need to both open the same load 


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## WronGun (Oct 18, 2013)

460 Delta said:


> I’m not sure I’m following you, but a simple series loop like an E-Stop comes to mind.
> Could you please describe the entirety of it with more detail?


Now I’m Seeing it it’s basically 2 Shut offs in series [emoji2359]

Can’t possibly get anymore basic lol 


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## Signal1 (Feb 10, 2016)




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## dspiffy (Nov 25, 2013)

I'm actually glad you posted this because I didnt understand what you were asking until it became obvious to everyone.


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## WronGun (Oct 18, 2013)

Im adding these secondary emergency shut off locations to jet fueling stations. The drawings only show rigid spec. Im wondering if any specialty fittings apply here ? These stations are out in the airfield on pedestals. 

I’ve only used specialty fittings when raceways out in the field enter buildings. 


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## yankeejoe1141 (Jul 26, 2013)

WronGun said:


> I’ve only used specialty fittings when raceways out in the field enter buildings.


Don’t you only need the special fittings when the conduit crosses the hazardous location boundaries?


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## WronGun (Oct 18, 2013)

yankeejoe1141 said:


> Don’t you only need the special fittings when the conduit crosses the hazardous location boundaries?


This doesn’t cross into the filling station. It will connect to the closest shut-off to the station which is about 15’ from the closest tank, it will provide an additional shut off further away out in the field about 3’ off of the drive path. 


It’s not a big deal add a couple fittings on each end of a run, but is it even necessary in this situation. 


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## yankeejoe1141 (Jul 26, 2013)

WronGun said:


> This doesn’t cross into the filling station. It will connect to the closest shut-off to the station which is about 15’ from the closest tank, it will provide an additional shut off further away out in the field about 3’ off of the drive path.
> 
> 
> It’s not a big deal add a couple fittings on each end of a run, but is it even necessary in this situation.
> ...


When you say special fittings you mean the ones you seal with the Chico compound? I think everything in the area still has to be rated for the class/div of the area, like any splice boxes and stuff. But you only need to seal it off if it crossed into other classified areas.

TBH I don’t do much classified areas so maybe someone with more experience could chime in.


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## 460 Delta (May 9, 2018)

yankeejoe1141 said:


> When you say special fittings you mean the ones you seal with the Chico compound? I think everything in the area still has to be rated for the class/div of the area, like any splice boxes and stuff. But you only need to seal it off if it crossed into other classified areas.
> 
> TBH I don’t do much classified areas so maybe someone with more experience could chime in.


This is where @oldsparky52 is the expert. Now where did he run off to??


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## splatz (May 23, 2015)

yankeejoe1141 said:


> Don’t you only need the special fittings when the conduit crosses the hazardous location boundaries?


You need a sealoff when the conduit leaves the hazardous location, but also at enclosures, there are some exceptions for switches / devices made for hazardous locations. There might be other rules for aircraft hangars, fueling, etc. that apply. You have to know how the locations are classified.


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## Almost Retired (Sep 14, 2021)

WronGun said:


> Im adding these secondary emergency shut off locations to jet fueling stations. The drawings only show rigid spec. Im wondering if any specialty fittings apply here ? These stations are out in the airfield on pedestals.
> 
> I’ve only used specialty fittings when raceways out in the field enter buildings.
> 
> ...


The last time i wired a fueling station, the Estops had to be outside of the Zone. So there were no chico fittings there

I hope you read thru 513 and 514 ?? they arent long or hard to understand


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## oldsparky52 (Feb 25, 2020)

splatz said:


> You have to know how the locations are classified.


This is the key. If the existing E-stop is out of the classified location and the conduit between this switch and the new switch does not enter a classified location then it is my understanding you would not need any sealoffs. 

That being said, you need to check job specs because more than once I've seen sealoffs called for when the NEC was not requiring them.

Since the switch is NC, then it sounds like a holding circuit for a contactor. If that's the case then it's just a matter of wiring the 2nd switch in series with the holding circuit (like 460 Delta mentioned).


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## Apelectric (Dec 6, 2017)

Depending on the size of the airport / amount of fueling going on and the location the EFSO can work in different sequences. 

We have terminal area fueling where if the EFSO is activated it shuts the local fuel valve (alarms sound, etc) but allows the pump, hundreds of feet or more away in the "fuel satellite", to keep running and fueling the other locations. I forget the number, but more than one EFSO has to be activated before shutting down the pump. There also might be a time limit for how long it can run with one EFSO activated but don't quote me on that. 

However, the transfer pumps, pumping from large fuel tanks in the "fuel farm", that pump to smaller but still very large tanks in the "fuel satellite ", only require one EFSO to be activated for the pump to stop.


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## splatz (May 23, 2015)

oldsparky52 said:


> This is the key. If the existing E-stop is out of the classified location and the conduit between this switch and the new switch does not enter a classified location then it is my understanding you would not need any sealoffs.


I think if the conduit passes through the boundary, it needs a sealoff near the boundary, is that correct?


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## Almost Retired (Sep 14, 2021)

splatz said:


> I think if the conduit passes through the boundary, it needs a sealoff near the boundary, is that correct?


yes but if its underground then as soon as it emerges from underground out of the zone


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## oldsparky52 (Feb 25, 2020)

splatz said:


> I think if the conduit passes through the boundary, it needs a sealoff near the boundary, is that correct?


If the conduit passes completely through the boundary with no fittings, it would not require sealoff's, but if there are fittings (couplings) in the classified location then seals are required. This is my experience with gas stations and u/g conduits. I would think the same applies to above ground conduits as well. 

We used to try really hard to route all site lighting, signs, etc. conduits so they never went through a classified location (in gas stations the area underground below a classified location was considered a classified location.


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## Southeast Power (Jan 18, 2009)

WronGun said:


> I don’t know why this isn’t clear to me, but I’m trying to draw out a circuit and not sure how to do it.
> 
> I have a fuel station at an airport that I need to integrate a secondary Fuel Shut-Off while keeping the first one also operational. How do I open the same circuit from 2 locations.
> 
> ...


Is the circuit maintained therefore a closed circuit or is it a shunt trip that needs to be parallel?
Im sure those in the petro side of the house would know. I would suspect it would be a loop that opens if there was a problem.


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## WronGun (Oct 18, 2013)

Southeast Power said:


> Is the circuit maintained therefore a closed circuit or is it a shunt trip that needs to be parallel?
> Im sure those in the petro side of the house would know. I would suspect it would be a loop that opens if there was a problem.


I’ll find out soon. I quoted it without seeing it, but I did have a good set of detailed prints showing the existing design. It’s spec’s show just as an EFSO shut-off. 


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## WronGun (Oct 18, 2013)

Southeast Power said:


> Is the circuit maintained therefore a closed circuit or is it a shunt trip that needs to be parallel?
> Im sure those in the petro side of the house would know. I would suspect it would be a loop that opens if there was a problem.


So this existing EFSO is spliced with 2 leads that go to the main Shunt trip. (load and neutral) Does this change my series shut off configuration ?

My existing EFSO has a feed from a 20A OCPD and the load is spliced with the shunt trip conductor to the panel 200A main. 


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## yankeejoe1141 (Jul 26, 2013)

WronGun said:


> So this existing EFSO is spliced with 2 leads that go to the main Shunt trip. (load and neutral) Does this change my series shut off configuration ?
> 
> My existing EFSO has a feed from a 20A OCPD and the load is spliced with the shunt trip conductor to the panel 200A main.
> 
> ...


I think it does change things because now instead of maintaining a NC circuit, you're going to have to feed a voltage to a shunt trip device.


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## oldsparky52 (Feb 25, 2020)

WronGun said:


> So this existing EFSO is spliced with 2 leads that go to the main Shunt trip. (load and neutral) Does this change my series shut off configuration ?
> 
> My existing EFSO has a feed from a 20A OCPD and the load is spliced with the shunt trip conductor to the panel 200A main.
> 
> ...


If you are controlling a shunt trip then it's not a holding circuit so you would parallel the new EFSO with the wiring of the existing EFSO.

If it was a contactor coil that was being controlled then the new EFSO would be wired in series with the existing EFSO.

Either way, you should be able to do it with 2 conductors coming from the existing EFSO. 

Did they call out a momentary or maintain operator?


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## oldsparky52 (Feb 25, 2020)

Oh yea, I HATE SHUNT TRIP E-stops. Control voltage gets lost and no one knows until the E-stop does not work. Bad design IMO. Yea, it's done a lot.


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## WronGun (Oct 18, 2013)

This is my current situation. 

My plan was to install the new EFSO in series but im unsure how this effects the ST


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## oldsparky52 (Feb 25, 2020)

WronGun said:


> This is my current situation.
> 
> My plan was to install the new EFSO in series but im unsure how this effects the ST
> 
> ...


I don't understand the line to "tanks". What is that?

With the shunt trip, you would parallel, not series wire the new EFSO to the existing EFSO. That line to the tanks is confusing, did I mention that? Is it the return from EFSO elsewhere and the line to those other EFSOs (if they exist) is not shown?


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## oldsparky52 (Feb 25, 2020)

Is there a breaker lock on that breaker feeding the EFSOs or can anyone turn it off? Is it a dedicated circuit to the EFSOs? 

Did I mention I don't like shunt trip E-stops?


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## oldsparky52 (Feb 25, 2020)

So you would use a NO switch with a momentary operator for the new EFSO?


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## WronGun (Oct 18, 2013)

oldsparky52 said:


> Is there a breaker lock on that breaker feeding the EFSOs or can anyone turn it off? Is it a dedicated circuit to the EFSOs?
> 
> Did I mention I don't like shunt trip E-stops?


It’s dedicated right off of a breaker to the existing EFSO, no lock 


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## WronGun (Oct 18, 2013)

This what I have 

Square D Control Station SER. B 9001BR103 600VAC 5A










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## WronGun (Oct 18, 2013)

oldsparky52 said:


> I don't understand the line to "tanks". What is that?
> 
> With the shunt trip, you would parallel, not series wire the new EFSO to the existing EFSO. That line to the tanks is confusing, did I mention that? Is it the return from EFSO elsewhere and the line to those other EFSOs (if they exist) is not shown?


Sorry, the line to the tanks is just the load 


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## yankeejoe1141 (Jul 26, 2013)

oldsparky52 said:


> I don't understand the line to "tanks". What is that?
> 
> With the shunt trip, you would parallel, not series wire the new EFSO to the existing EFSO. That line to the tanks is confusing, did I mention that? Is it the return from EFSO elsewhere and the line to those other EFSOs (if they exist) is not shown?


Could that line to the tank be the power to the pump? I would call the engineer and ask but I couldn’t see his stamp on the drawings lol!


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## WronGun (Oct 18, 2013)

yankeejoe1141 said:


> Could that line to the tank be the power to the pump? I would call the engineer and ask but I couldn’t see his stamp on the drawings lol!


The load from the EFSO goes to the shunt and there is also another wire spliced with it, but there is no other shut off I’ve been told about. I’ll need to look into it. 


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## oldsparky52 (Feb 25, 2020)

WronGun said:


> The load from the EFSO goes to the shunt and there is also another wire spliced with it, but there is no other shut off I’ve been told about. I’ll need to look into it.
> 
> 
> Sent from my iPhone using Tapatalk


If you do chase it down, could you let us know what it is? I suspect there is another device to operate the shunt trip. What I'm really curious about is whether it's fed from the same power source as the EFSO device you have seen, or is it power from a different circuit. It should be from the same circuit, but it would work if powered from a different circuit.


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## WronGun (Oct 18, 2013)

oldsparky52 said:


> If you do chase it down, could you let us know what it is? I suspect there is another device to operate the shunt trip. What I'm really curious about is whether it's fed from the same power source as the EFSO device you have seen, or is it power from a different circuit. It should be from the same circuit, but it would work if powered from a different circuit.


Same circuit, why do you not like shunt trips ? Just wondering. I’m not that experienced with them, that’s why all the questions, but it seems like a very simple circuit. A feed, with a push button that closes a circuit that goes to the ST terminals on the main creating a trip that shuts down everything. Is there something I’m not aware of here ? 

All it seems I have to do is splice the same circuit feed carry it to the new switch with an additional load to splice with the other loads and a ground of course. Wired in parallel so both EFSO’s send power to the ST, tripping the main.

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## oldsparky52 (Feb 25, 2020)

WronGun said:


> Same circuit, why do you not like shunt trips ? Just wondering. I’m not that experienced with them, that’s why all the questions, but it seems like a very simple circuit. A feed, with a push button that closes a circuit that goes to the ST terminals on the main creating a trip that shuts down everything. Is there something I’m not aware of here ?


 Imagine this, (



) a fire starts somehow near the fuel system. Someone runs to hit the E-stop and it doesn't work. It doesn't matter why, it could be someone turned off the breaker, or the E-stop contacts didn't make for some reason, or someone messed where they were not supposed to and disconnected the wiring for the shunt trip. Any number of things could disable the E-stop circuit and you never know until you need it. 

Now, if the EFSO was a holding circuit for a contactor, then for ANY reason the control circuit loses power, the E-stop system fails off where with a shunt trip E-stop system it fails on. IMO a very bad design. The time to find out your E-stop system is defective is NOT when there is an emergency situation. This is just my opinion, shunt trips are used all the time.


> All it seems I have to do is splice the same circuit feed carry it to the new switch with an additional load to splice with the other loads and a ground of course. Wired in parallel so both EFSO’s send power to the ST, tripping the main.


Sounds like you got it. 

Thanks for sharing the details.


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## Southeast Power (Jan 18, 2009)

WronGun said:


> I don’t know why this isn’t clear to me, but I’m trying to draw out a circuit and not sure how to do it.
> 
> I have a fuel station at an airport that I need to integrate a secondary Fuel Shut-Off while keeping the first one also operational. How do I open the same circuit from 2 locations.
> 
> ...


They need to be in series but, do yourself a favor and order both an N.O. And N.C. set of contacts if they are not shipped that way.


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## WronGun (Oct 18, 2013)

Southeast Power said:


> They need to be in series but, do yourself a favor and order both an N.O. And N.C. set of contacts if they are not shipped that way.


How would this work in series ? Both shut offs are an momentary contact that sends 120v to the ST terminals. They both need power and a load constantly.

If I wired them in series the second EFSO wouldn’t work unless the first EFSO is being held in the closed position. 

We have 2 N.O shut offs 


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## Almost Retired (Sep 14, 2021)

the one that i put in was a maintained button ....
if the original was momentary, then i would think it had a relay seal in system

like a motor starter with aux contacts and 2 momentary buttons

cause i sure would not want to stand there and hold it while the fire raged

the momentary may be to prevent walking all the way back to the button to reset it after the fire was out
a convenience thing
in which case there should be a momentary "Start" button somewhere
maybe the original button is push pull ?
or it may be a separate "Enable" button at the pump control station

Over all it sounds like you need to investigate the original control installation completely
I am assuming that you did not find the control system on your drawing?
if you havent bid it yet, add the time to do that to your bid


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## oldsparky52 (Feb 25, 2020)

I think he's got it perfect.


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## WronGun (Oct 18, 2013)

Almost Retired said:


> the one that i put in was a maintained button ....
> if the original was momentary, then i would think it had a relay seal in system
> 
> like a motor starter with aux contacts and 2 momentary buttons
> ...


Why would there be a relay ? There’s no load on this circuit.


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## WronGun (Oct 18, 2013)

So this job is breaking ground tomorrow. Combing through the very detailed engineered plans of the existing and new work to be performed. Even metering the shut offs checking for proper function. The engineers spec’d out normally closed EFSO’s to be integrated into a Normally open EFSO network. [emoji2359]

Rang their phone pointing out the error on the plans. Just wondering, Is this worth a bonus ? [emoji23]


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## backstay (Feb 3, 2011)

Almost Retired said:


> yes but if its underground then as soon as it emerges from underground out of the zone


Within 10 feet of where it emerges. But no fittings allowed before the seal off.


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## splatz (May 23, 2015)

WronGun said:


> So this job is breaking ground tomorrow. Combing through the very detailed engineered plans of the existing and new work to be performed. Even metering the shut offs checking for proper function. The engineers spec’d out normally closed EFSO’s to be integrated into a Normally open EFSO network.
> 
> 
> 
> ...





Southeast Power said:


> Is the circuit maintained therefore a closed circuit or is it a shunt trip that needs to be parallel?
> Im sure those in the petro side of the house would know. I would suspect it would be a loop that opens if there was a problem.





oldsparky52 said:


> If you are controlling a shunt trip then it's not a holding circuit so you would parallel the new EFSO with the wiring of the existing EFSO.
> If it was a contactor coil that was being controlled then the new EFSO would be wired in series with the existing EFSO.
> Either way, you should be able to do it with 2 conductors coming from the existing EFSO.
> Did they call out a momentary or maintain operator?


Ask for a bonus, and if they get it, you split it up and send it to @Southeast Power and @oldsparky52 along with their engineering fees. Ask for a lot of money and some free Cinnabons from the airport terminal shops.


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## WronGun (Oct 18, 2013)

So we did all the conduit runs today. I think i messed up on the circuitry. Haven’t done this part yet. This is the existing Estop. 




















My estops that were spec’d by engineering have continuity when not pressed and open when pressed. 

Unfortunately, testing all this while an airport is running is a little difficult. 

I understood the estop closes when pushed and sends voltage to the shunt for a trip. 

Do I not want to turn the estop OCPD off when tying in? Im still a week away from wiring all this in.


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## 134sparky (Feb 27, 2014)

WronGun said:


> Do I not want to turn the estop OCPD off when tying in?


I mean you can do it live if you want but what if you accidentally push the e stop, then the pumps shut down and you have an even bigger breaker to reset. I would turn the e stop breaker off

If you're concerned about having the other e stop off line I would just have one guy by the panel, flip the breaker providing power to e stop, splice in the new one then turn the breaker back on. That should be like 5-10 minutes down time without e stop tops. Tell whomever needs to know in an email ahead of time.

Looks like the existing is wired N.O. so your new e stop should also be wired N.O. and be wired in parallel not series. 

Sounds like you figured that out but are second guessing yourself?


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## WronGun (Oct 18, 2013)

134sparky said:


> I mean you can do it live if you want but what if you accidentally push the e stop, then the pumps shut down and you have an even bigger breaker to reset. I would turn the e stop breaker off
> 
> If you're concerned about having the other e stop off line I would just have one guy by the panel, flip the breaker providing power to e stop, splice in the new one then turn the breaker back on. That should be like 5-10 minutes down time without e stop tops. Tell whomever needs to know in an email ahead of time.
> 
> ...


I’m just overthinking everything and trying to be as cautious as possible. Anyways my dilemma is solved. They are abandoning one of the E stop locations and approved us to seal that location and move that 1 unit to the location that needs to be done asap for FAA inspection. I’m more at ease now as there is nothing more to figure out. 


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## 134sparky (Feb 27, 2014)

I hear ya. Glad it worked out but now they're going to want money back because you didn't have to put in a second one


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## splatz (May 23, 2015)

There are NO and NC contacts on those blocks.


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## 134sparky (Feb 27, 2014)

splatz said:


> There are NO and NC contacts on those blocks.


Yep but not the one he was provided in post #31, it's only N.C.

I've been in the position where a PM ordered me the wrong estops. Now I either give them an exact model number or just tell them to get the ones that have 1 N.O. and 1 N.C. even when I don't need it.


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## WronGun (Oct 18, 2013)

134sparky said:


> I hear ya. Glad it worked out but now they're going to want money back because you didn't have to put in a second one


lol, that’s definitely not happening. I’m keeping the $450 square D E-stop and they will be billed for it. 


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## glen1971 (Oct 10, 2012)

FWIW, on a couple of our sites with shunt trips that are NO control and energize to trip, I added a 120 volt relay on the supply side, upstream of the switches, and wired a 24 vdc input to the PLC from the NO on the relay. That way if the supply breaker was shut off for maintenance, an alarm is generated.


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## WronGun (Oct 18, 2013)

We are still working on this project. It’s 90% done. We do have an issue though. 

FAA was on site for testing. 

They pushed our EFSO and the shunt tripped as it should. However, it wouldn’t reset. 

I went back on an emergency call. The other existing EFSO was sending voltage to the spliced load to the shunt trip. 

We are replacing the old EFSO now, but even after disconnecting the old EFSO the line still has voltage going to the shunt trip. I couldn’t get into much testing because a fuel tanker was there waiting to unload. 

Not sure what caused this yet, nothing was changed on our end on this circuit. All we did was relocate 1 EFSO.


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## glen1971 (Oct 10, 2012)

WronGun said:


> We are still working on this project. It’s 90% done. We do have an issue though.
> 
> FAA was on site for testing.
> 
> ...


I'm just guessing but, maybe maintained contacts on your new switch, instead of momentary? Holding contacts needing a reset on the shunt trip circuit?


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## oldsparky52 (Feb 25, 2020)

WronGun said:


> The other existing EFSO was sending voltage to the spliced load to the shunt trip.


Can you elaborate this point?

What I understood is the new shunt trip was tested, worked, and now you have a new problem of voltage coming from the existing EFSO? The "spliced load to the shunt trip" is what has me confused as to exactly what this means. The shunt trip is the load. 

Sorry.


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## WronGun (Oct 18, 2013)

oldsparky52 said:


> Can you elaborate this point?
> 
> What I understood is the new shunt trip was tested, worked, and now you have a new problem of voltage coming from the existing EFSO? The "spliced load to the shunt trip" is what has me confused as to exactly what this means. The shunt trip is the load.
> 
> Sorry.


These are photos from before we touched anything. The yellow wire is to the shunt.
The 2 black wires are from each EFSO. No voltage on these until the EFSO’s are pressed, whichever one. 

After they ran their test. The breaker wouldn’t reset because one of these wires (old ESFO)held 120v. Something completely new.












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## Forge Boyz (Nov 7, 2014)

WronGun said:


> These are photos from before we touched anything. The yellow wire is to the shunt.
> The 2 black wires are from each EFSO. No voltage on these until the EFSO’s are pressed, whichever one.
> 
> After they ran their test. The breaker wouldn’t reset because one of these wires (old ESFO)held 120v. Something completely new.
> ...


Is one of the contacts stuck closed? If they aren't operated much, which I imagine is the case, sometimes a contact gets sticky. 

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## oldsparky52 (Feb 25, 2020)

Shouldn't be too hard to find the problem.


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