Isolation Modules

[Tom McNamara]

I am new to the forum and would appreciate any input on this subject especially from an AHJ viewpoint:

I am contractor installing an addressable local system in a residential 4 apartment wood constructed building. My understanding is that isolation modules are required between floors to prevent a circuit fault on one floor from affecting the circuit on another floor and I would like to know if isolation modules are necessary on both the initiating and notification circuits and if so are they required at :

1.) every point where a floor transition is made on a circuit from a device on one floor to a device on another floor in the circuit (ie basement to 1st floor initiating device and back to basement initiating devices) and

2,) are IMs required when transitioning between floors only for the purpose of running conductors with no devices on the circuit of the intermediary floor (ie basement to 1st floor initiating device back to basement then to another 1st floor initiating device).

Thanks very much for any input on this subject.

[Paul Desorcy]

I am new to the forum and would appreciate any input on this subject especially from an AHJ viewpoint:

I am contractor installing an addressable local system in a residential 4 apartment wood constructed building. My understanding is that isolation modules are required between floors to prevent a circuit fault on one floor from affecting the circuit on another floor and I would like to know if isolation modules are necessary on both the initiating and notification circuits and if so are they required at :

1.) every point where a floor transition is made on a circuit from a device on one floor to a device on another floor in the circuit (ie basement to 1st floor initiating device and back to basement initiating devices) and

2,) are IMs required when transitioning between floors only for the purpose of running conductors with no devices on the circuit of the intermediary floor (ie basement to 1st floor initiating device back to basement then to another 1st floor initiating device).

Thanks very much for any input on this subject.

Hello Tkmcnam, What is your name? What community are you in? Is it Rhode Island?

In Rhode Island, when you break the floor with the SLC you shall install an Isolation Module on one side of the circuit to isolate it for a short or failure on the other side of the circuit. When you again break the floor when leaving the floor you shall install another Isolation Module either on that floor or on the next level, before the next device. Also, if there are more than 25 devices per level there shall be Isolation Modules to separate the groups, (no more than 25 per group). If you are going up and down through floors with your SLC through-out the building, I suggest that you take another look at your design, this seems to be an inefficient way of getting the job done.

On the matter of Isolation Modules for the Notification Appliance Circuit, I suggest that you read your manual for the type of system that you are installing. I would have to say that the manual is your best friend at this point. Also, if you are going to be installing Fire Alarm Systems, you need to invest in a copy of NFPA 72, NFPA 1 & 101 wouldn't be bad either. The RI state Fire Code is readily accessible if you are conducting work in RI. In the future for bidding jobs these books would be very helpful.

P.S, don't forget to get your permits.

[Tom McNamara]

Thanks for you help Paul.
My name is Tom McNamara and I'm with JJ McNamara and Son Inc. electrical contractors located in Cranston, RI.  I have the books you referenced and I was inquiring about this subject because the customer would like to avoid the appearance of conduit where possible so I was trying to make as much use of the basement as possible for running the circuit conductors. 

[Tom McNamara]

Should have mentioned one other question Paul...in your response you state an IM is required when again breaking the floor "before the next device"  does that mean an IM is required even if there are no devices on the cirucit at the new floor level (ie break the floor from 1st floor to basement and return to the 1st floor with no device in the basement) ?  Thanks again for your help.

In Rhode Island, when you break the floor with the SLC you shall install an Isolation Module on one side of the circuit to isolate it for a short or failure on the other side of the circuit. When you again break the floor when leaving the floor you shall install another Isolation Module either on that floor or on the next level, before the next device. Also, if there are more than 25 devices per level there shall be Isolation Modules to separate the groups, (no more than 25 per group). If you are going up and down through floors with your SLC through-out the building, I suggest that you take another look at your design, this seems to be an inefficient way of getting the job done.

[Paul Desorcy]

Thank you Tom, I make every effort to have our forum open to everyone so we need some info at minimum.

RIUFC:13.8.10.4.4.1
States "When a common SLC serves more than one floor of a building, fault isolation modules shall be installed to prevent a wire to wire short circuit fault on one floor from disabling the SLC on any other floor."

The intent is not to isolate just wire. Your design should be adjusted so that you do not go in and out of levels. If I was the inspector I would have an exception with that; You really need to have a design and approved plans in place with a wiring riser diagram.

The wiring riser diagram would show everything. If you have a hard ship, be upfront about it with the Fire Marshal. Don't let the Fire Marshal find it on their own, talk to them about your design.

I now understand your dilemma about what the customer wants. Is it impossible to snake the cables? Go from closet to device in the kitchen to H/S then up to next device? I don't know what your bldg is like.

The proper layout should be lateral through the apartment then proceed to the next apartment then go up or down from an Isolation Module. The last device, let's say from the attic, can go directly to an IM at the panel. Don't forget 1 foot vertical and four foot horizontal.

Maybe a conventional system would fit this bldg. better. Branch out from the hallway to the apartment, then go up and down with the circuits. An addressable system is not always the easiest or cheapest way, you need to weigh all the options. Talk to the AHJ in that community, ask some questions from them.

Good Luck.

[Tom McNamara]

Thanks Paul.  Your input has been very helpful and it appears you clearly understand the constraints the customer is placing on me.  I had initially considered a conventional zoned system but thought the addressable system would provide a more robust design...I'm going to take your advice and reconsider the zoned option.  I'll also speak with the AHJ and I hope he's as helpful as you have been.  I apologize for my rookie questions but like everyone else I know I need to start somewhere, so you can expect more in the future.  My Dad started our business over 30 years ago and we do everything by the book so you can be assured there will be no shortcuts.  I plan to become a member and hope to meet you at a future meeting.

[Paul Desorcy]

We have meetings on the first Thursday of the month, usually in East Greenwich. This month there is a tour of the Grinnell Sprinkler facility in Cranston but we are holding our meeting first in a room provided. If you want to join our Association you can do that then if you like.

Thanks.