Toggle switch as disconnect for dry-sprinkler air pump.

[A. Ingersoll]

Preface: I have limited experience with pumps and motors associated with the fire sprinkler system.

On a project we recently completed the building inspector had issue with the sprinkler pipe travelling though the insulated attic. Rather then heating and/or insulating the attic the customer opted to convert the sprinkler to a dry system. They installed a pump to regulate the air pressure in the pipe. I became aware of this change the next day, also coincidentally the day the fire and electrical inspector were due to visit the site. So i ran 12/2 MC with a dedicated 20A breaker and locked it in the on-position. I used a 20A commercial grade toggle switch as a disconnect (Labled as a disconnect with the circuit number and the device it services) just to get the job done quickly with what I had on the truck. Nobody even looked at it or questioned it or asked me about it and there was no issue...
i'm not worried about using a switch as a disconnect for a motor. I'm more worried about the fact that its associated to the sprinkler system.

My question is:
"Is the 20A commercial grade toggle switch suitable for use as a disconnect for this pump associated with the sprinkler system."

 

[kwired]

This air pump is not critical to the primary function of the sprinkler system, and in fact is not even needed once the system is actively performing it's primary function. Should the air pump fail (whether it be the switch or anything else) there should be controls that give a trouble alert once pressure drops below a specific level.

 

[augie47]

Per NEC 430.102(B) you need the disconnecting means and per 430.109 (C) your switch is most likely suitable but you should take a look at that section to see if it meets the rating criteria .

As kwired mentioned, any action with the switch will not cause the sprinkler system to "activate"

 

[luckylerado]

I had done several of these and always used a toggle switch until I was encouraged by a sprinkler fitter to start using a cord an plug.

The air pressure is suppose to be supervised. Low pressure is generally a supervisory signal. High pressure nearly always indicates a trip and is essentially a water-flow and should be an alarm condition.


NFPA 72 2013
17.16.2.2.2 Dry Pipe Sprinkler System.
(A) "A pressure supervisory signal?initiating device for a drypipe sprinkler system shall indicate both high and low pressure conditions".

There are exceptions in NFPA 13 I believe but they involve large air chambers or "utility" type air supply with sufficient pressure to restore the system pressure within like 30 min or some such. I cannot reference a section out of 13.

Was the system tested per NFPA and water flowed?

 

[kwired]

I had done several of these and always used a toggle switch until I was encouraged by a sprinkler fitter to start using a cord an plug.

What was the justification for using a cord and plug? Sure it can be considered a disconnecting means for equipment that is permitted to be connected via cord and plug, but this application is not too likely to be permitted to be connected via cord and plug. 407(A)(7), (8) and (10) are possibilities, but need a little extra justification IMO. Conditions of (7) can usually be taken care of with flexible conduit.

 

[sparkyrick]

What was the justification for using a cord and plug? Sure it can be considered a disconnecting means for equipment that is permitted to be connected via cord and plug, but this application is not too likely to be permitted to be connected via cord and plug. 407(A)(7), (8) and (10) are possibilities, but need a little extra justification IMO. Conditions of (7) can usually be taken care of with flexible conduit.

I've seen dry system that just use a standard plug-in air compressor.

 

[kwired]

I've seen dry system that just use a standard plug-in air compressor.

I have as well, but that is because the compressor is listed as a portable unit and usually comes as a unit with cord/cap already installed on it. If it would be a fastened in place type of unit, a cord and plug is less likely to be acceptable method of connecting it.

 

[luckylerado]

What was the justification for using a cord and plug? Sure it can be considered a disconnecting means for equipment that is permitted to be connected via cord and plug, but this application is not too likely to be permitted to be connected via cord and plug. 407(A)(7), (8) and (10) are possibilities, but need a little extra justification IMO. Conditions of (7) can usually be taken care of with flexible conduit.

In this case I believe he prefers cord and plug so he does not need to have an electrician present in order to change out a compressor. A safety and or union thing no doubt. Frankly I did not need much convincing as this method saves time and money, and their equipment does not need to be there in order for me to finish my scope of work.

What makes you feel like this application would not permit a cord and plug disconnect. We are only talking about a little off the shelf and factory wired fractional horse compressor.

What section are you referring to?

 

[kwired]

In this case I believe he prefers cord and plug so he does not need to have an electrician present in order to change out a compressor. A safety and or union thing no doubt. Frankly I did not need much convincing as this method saves time and money, and their equipment does not need to be there in order for me to finish my scope of work.

What makes you feel like this application would not permit a cord and plug disconnect. We are only talking about a little off the shelf and factory wired fractional horse compressor.

What section are you referring to?

So the equipment guy has authority to create his own code?

I did mention 400.7(8) which is good enough to allow those small off the shelf compressors mentioned. Then again there is a good chance you wont find many of them (if any) that are listed to be used as a permanent fixture for such an application either, they are all portable in their design and probably listed as such.

We could all save money if we went by our own codes, we could also end up in huge lawsuits when our installs end up claiming lives and damaging property because we made our own codes.

 

[A. Ingersoll]

I am confident that the switch can handle the load of the pump. I am hesitant to use plug-and-cord for this application because it is easiest to access though a drop-ceiling, so one might say its "above a drop ceiling" even though the platform directly below it is a hard ceiling. My only fear was that someone might accidentally turn the switch in the "off" position and if there was a code dictating what equipment I should use. In truth, the pump has been accidentally turned off since it's installation (I believe the sprinkler guy never turned it on after he completed his installation) and the trouble was sent to the supervisory company and a bit of a mess was made... Now that I know code-wise I was in the right, generally speaking is there something better to use? I thought about using the guard from a burner plate to prevent people from accidentally turning it off, but really how idiot-proof can I be expected to make it?

 

[luckylerado]

So the equipment guy has authority to create his own code?

Uhh. No. However I find it in my best interest to accommodate the other trades when they make a request for something simple things like this.

I did mention 400.7(8) which is good enough to allow those small off the shelf compressors mentioned. Then again there is a good chance you wont find many of them (if any) that are listed to be used as a permanent fixture for such an application either, they are all portable in their design and probably listed as such.

There is no such requirement in NFPA 13 or 72 as far as I know. we are talking about relativity low pressures required to maintain the bladder in the dry types system. I have dones some fairly large scale projects with dry type systems throughout and never ran across a compressor larger than you might have on a job site to frame a house. These are basically just keeping a bladder full of air to keep the water off of the dry chemicals in the pipes until there is a trip.

We could all save money if we went by our own codes, we could also end up in huge lawsuits when our installs end up claiming lives and damaging property because we made our own codes.

Except to say that the receptacle must be horse power rated (same applies to a toggle switch BTW), there is nothing prohibiting cord and plug disconnect of a sprinkler compressor. I like your passion though.

 

[kwired]

I am confident that the switch can handle the load of the pump. I am hesitant to use plug-and-cord for this application because it is easiest to access though a drop-ceiling, so one might say its "above a drop ceiling" even though the platform directly below it is a hard ceiling. My only fear was that someone might accidentally turn the switch in the "off" position and if there was a code dictating what equipment I should use. In truth, the pump has been accidentally turned off since it's installation (I believe the sprinkler guy never turned it on after he completed his installation) and the trouble was sent to the supervisory company and a bit of a mess was made... Now that I know code-wise I was in the right, generally speaking is there something better to use? I thought about using the guard from a burner plate to prevent people from accidentally turning it off, but really how idiot-proof can I be expected to make it?

One could use the mentioned guard, a padlock attachment, a cover with a lid (weatherproof style may be easiest thing to find with a lid), fused or non fused safety switch, pull out disconnect switch like is common for use with air conditioning equipment, circuit breaker in a two space loadcenter even.

Though it may not be required to label it if it is obvious what it supplies, it may still not be a bad idea to put a label on it and especially if it is a similar toggle switch as most general lighting switches in the area maybe that helps keep it from getting turned off unintentionally. Locating it somewhat "out of the way" helps as well. By this I mean don't located it right next to the exit of the room so it is easily confused with lighting switches.

Cord and plug could be easily disconnected as well - especially by anyone not knowing what this compressor is for, so it may not be a bad idea to label that either.

 

[John120/240]

What kwired said, Plus use a Red single pole toggle switch.