# Introduction and basic questions on chemical feeder



## bostongtp (Apr 9, 2014)

Welcome to the forum. 

There’s some complexity with your question and without seeing the existing equipment it’s hard to gauge what the best apparatus to use is. Are you in the states or are you in Canada? If your in the States I would say take a look at Disconnects and disconnecting means in the NEC electrical code book, I think it’s article 430.

I say this with all due respect, if your not a licensed electrician don’t question the electrical contractor on what pieces of equipment and the methods he uses to plan and install them. Because he, just like you, is trained in his area of the trade and I’m sure he won’t use garbage materials. 

The codes that we follow are in place to keep trained and untrained personnel as safe as possible. And if your not trained and licensed you shouldn’t be opening the controller and probing around, you should call an electrician. I would simply address your concerns with the contractor and ask him what the options are.

Controllers are required to have a disconnecting means within sight of the equipment, I’m not sure to be honest if it has to be lockable. It’s in article 430.102. I’ll list a couple disconnects that would probably work for your application and are cheap.

Always remember lock out tag out equipment.

Products:
-Square D 2510FG2 Starter
-30 amp 600v 3-pole 3-phase snap style switch


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## MDShunk (Jan 7, 2007)

Are these chemical feed pumps all of the typical cord and plug connected type?


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## gpop (May 14, 2018)

soda ash is a powder that is mixed with water then released into the system if i remember correctly. So generally you have a feed screw and a small batch tank which is agitated.

A electrical contractor will do the install but as a plant operator you still have input into the install that goes past the minimum of code. 

120v disconnects are cheap so add as many as you like on the incoming feed to the dc drives. Switching dc requires heavier duty parts so its cheaper to keep the disconnects on the ac side, Its also not a good idea to open or close the dc while the drive is running. Your electrician will have to calculate voltage drop based on the additional length of the wire.

As for protection most of this is controlled by the drive and the fuses on the board. 

If i was installing something like this i may add a wirry-gig to the screw to prove that the screw was turning. Getting feed back to the plc that something has broken, fuse has blown or someone has turned off a disconnect may be useful from a automation point of view.


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## mburtis (Sep 1, 2018)

Hello all been a couple of months since I started this topic but Im back.

Anyway yes soda ash is a dry powder that is mixed with water and then fed into the effluent piping. The system consists of two eagle microsystems VF100 volumetric feeders and a in tank mixer. The mixer and 1 feeder runs 24-7. 

Like I said before the two feeders and the mixer are on a single 20 amp breaker in a panel upstairs. My main question is what sort of disconnect is really required, I want to have a separate disconnection means for each controller and the mixer ( three separate disconnects). 

We discussed just putting the controllers on a plug and socket and not having to worry about it. There was some question about whether a plug and socket was designed for 24-7 operation. Ive been researching disconnects and there are so many different kinds its hard to sort through,UL98, UL508, etc.)

Would something as simple as a toggle switch (hubble hbl7832D) be acceptable as a disconnect for the motor drive or say an eaton R5 series rotary disconnect? Or since it is a controller (just a 0-90VDC SCR drive with a pot and an one off switch) does it need something higher class like a two pole safety switch? 

Thanks for the help.


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## MikeFL (Apr 16, 2016)

Keep in mind you have NEC requirements and then you have OSHA requirements. You really should have a qualified engineering firm on retainer to help you with these things. Between the risk of blowing up equipment and someone getting hurt, it's money well spent. A peer review is always wise especially when dealing with safety and expensive or critical equipment.


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## John Valdes (May 17, 2007)

Welcome to Electrician Talk.
Thanks for taking the time to fill out your profile.

I did not read your post. I just checked your profile.
Does the disco need to have a place to lock it in the open position? LOTTO?


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## JRaef (Mar 23, 2009)

There are two issues involved here: The NEC requirements for a disconnecting device, and OSHA requirements for having the ability to perform Lock-Out / Tag-Out (LO/TO).


If it is a plug-in device, that equates to being a way to disconnect power per the NEC, but you might consider adding a locking cover for the plug as a proper LO/TO point as well. 



The Hubbell toggles that you posted are legal disconnect devices as well, and you can get padlocking accessories for those to add LO/TO.


The little automotive style toggle switches MIGHT be legal disconnecting devices (depending on the rating, they must have a HP rating equal to or greater than your motor) and they too can have a padlocking attachment added for LO/TO, but those are few and far between;


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## mburtis (Sep 1, 2018)

JRaef thanks for the information, The automotive toggle switches included with the controllers have either 15 or 20 amp rating and are rated at 3/4 hp if i remember right. I looked them up, cant remember what company they were but they looked pretty good.

From a control stand point they do disconnect power to the control board, thereby eliminating the power source for the motor. Something about using them as the local disconnect/lOTO device struck me as odd and i had questions about them breaking the circuit under full load (emergency).

From the reading i have done it seems that the SCR controller would be considered a motor controller (basically the same as a VFD) by code so needs a disconnect on the line side within sight, (the controllers are right next to the motors so no need to worry about another line of sight one for the motors). Only thing Im not 100% sure on is what certification this disconnect needs to meet. 

Does the certification change because this is a 120V single phase system? Im sure the answer is in the code, ill dig out the copy at work on monday and look through it.


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## JRaef (Mar 23, 2009)

mburtis said:


> Only thing Im not 100% sure on is what certification this disconnect needs to meet.
> 
> Does the certification change because this is a 120V single phase system? Im sure the answer is in the code, ill dig out the copy at work on monday and look through it.



"Certification" is only in that if used in a motor circuit, the device must have a *motor rating* equal to or greater than the motor involved. So you say that the switches are rated for 3/4HP at 120V, but you don't state the size of your motor. If it is 3/4HP or less, that switch meets the requirement. At 6.8A @ 120V I'm pretty sure it's around 1/3HP so most likely yes.


But as I said, it is usually difficult to find a proper lock-out device for an automotive style toggle switch. I posted one for you, it is the only one I could find.
(Not that I tried all that hard though, it's not my project :wink


OSHA, not the NEC, requires that you must have a way to disconnect power AND lock it so that if you are working on the machine, ONLY YOU can unlock it to apply power, and it needs to be in a clear line of sight to the machine. A toggle switch with no locking mechanism is subject to someone walking up and flipping the switch (or perhaps bumping it with a broom handle) while you have your hands or fingers on live parts. If you can't add a locking method to that switch, it will not meet that OSHA requirement.


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## mburtis (Sep 1, 2018)

hmm interesting ive been going down a rabbit hole of ul98 vs ul508 etc etc. (part of being a recovering engineer). the feeder motors are 1/6 hp 90vdc if i remember right. The automotive style switches are the main power switches on the scr speed control and then the motors are powered by the controller. Im likely overthinking this but its interesting research for me.


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## mburtis (Sep 1, 2018)

Possibly since this is a 120v application the disconnect requirements are simpler? I have seen various shields for the toggle switches that would probably work to satisfy LO/TO. Sure would simplify things and save some money. Got some more research to do.


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## JRaef (Mar 23, 2009)

mburtis said:


> Possibly since this is a 120v application the disconnect requirements are simpler? I have seen various shields for the toggle switches that would probably work to satisfy LO/TO. Sure would simplify things and save some money. Got some more research to do.



The UL508 listed disconnects must have ANOTHER device ahead of them as the Branch Disconnect device, either a UL98 listed disconnect or a UL 489 listed circuit breaker. That issue is not applicable here, assuming you have a 1 pole breaker feeding this somewhere, because that will be UL489 listed and thereby that is the branch device already. So you can use anything you like down stream, i.e. a UL508 rated component (or other similarly UL listed device), hence the toggle switch being good (assuming it is UL listed). So it's not that the rules are necessarily simpler, it's just that by their very nature, 120V circuits tend to already satisfy a lot of these issues from the beginning.


Just so you know, little aircraft style flip-up SHIELDS that keep you from accidentally flipping a toggle switch are NOT the same as LO/TO (Lock Out / Tag Out) because most of them cannot be locked and tagged.


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## mburtis (Sep 1, 2018)

yea i knew the breaker would satisfy the main disconnect requirement but i wasn't sure about within sight requirments. The breaker is upstairs and across the plant.


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