Smokes in a dwelling with an apt

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I am wiring a home that will have a mother in law apartment in part of the basement. At some point it may be a rental. Home owner wants a separate meter and wants just standard smoke and carbon detectors- line voltage. I would want the apartment and the house to be tied together but I am not sure that would be compliant. I am assuming I cannot have a branch circuit from the home be connected to a device in the apartment since they are separate meters. Any thoughts.

I assume that I don't have to tie them together but I would surely want it in my home. Is the only way to do this thru a LV system?
 

kwired

Electron manager
Location
NE Nebraska
I think separate meters means nothing. Separate occupancies however does have some meaning.

I can think of several places I have done work that had more than one meter for whatever reason that was still only one occupancy. Maybe they have a three phase service and a single phase service, different voltage services, different rate for specific types of equipment, etc are all reasons to have multiple meters for a single occupancy.
 

mgookin

Senior Member
Location
Fort Myers, FL
It's very common to have multiple meters/ services in a single occupancy (tenant space). We always require them to be labeled 1of2, 2of2, or whatever is appropriate.

Sounds like you're setting up for a duplex. Those smokes are not required to be interconnected from one dwelling unit to the other. Not required does not mean prohibited.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
It's very common to have multiple meters/ services in a single occupancy (tenant space). We always require them to be labeled 1of2, 2of2, or whatever is appropriate.

Sounds like you're setting up for a duplex. Those smokes are not required to be interconnected from one dwelling unit to the other. Not required does not mean prohibited.

It is not really a duplex but a few rooms in part of the basement that will be an efficiency apt. I realize that the smokes may not be required to be connected but "what if" I wanted them wired that way. If I owned the home I would want my smokes to go off if the apt had a fire. I guess as long as there is a true fire wall between the structures it wont be important to tie them together
 

John120/240

Senior Member
Location
Olathe, Kansas
It is not really a duplex but a few rooms in part of the basement that will be an efficiency apt. I realize that the smokes may not be required to be connected but "what if" I wanted them wired that way. If I owned the home I would want my smokes to go off if the apt had a fire. I guess as long as there is a true fire wall between the structures it wont be important to tie them together
I would run a 3 wire between smokes in both units. Connect/disconnect each end of this 3 wire depending on your needs. Disconnect power at one end when both systems are tied together.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
It's very common to have multiple meters/ services in a single occupancy (tenant space). We always require them to be labeled 1of2, 2of2, or whatever is appropriate.

Sounds like you're setting up for a duplex. Those smokes are not required to be interconnected from one dwelling unit to the other. Not required does not mean prohibited.
Ahhh, sorry, in this case it is prohibited by NFPA 72 and IIRC the IBC as well. A low voltage system is the answer.
 

novemberaudi

Member
Location
boston
It is always a problem in two family dwellings on common area issues like fire alarm. If there are two meters and the property is sold and only the in law apartment is rented and there is no meter for the main house will there be no protection for the apartment?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
It is always a problem in two family dwellings on common area issues like fire alarm. If there are two meters and the property is sold and only the in law apartment is rented and there is no meter for the main house will there be no protection for the apartment?

That's a good point but that would be an unlikely scenario. It could happen so I may just see how the town wants to deal with this. I suspect there will be 2 separate systems.
 

James L

Senior Member
I would think that smokes should be wired separately for each unit, especially if the apartment is going to get a separate meter. But they can still be interconnected if you want:

Wire all smokes in house together, and all the ones in apartment together. But don't wire between the units.
Install normal smoke detectors at each location except for one in house and one in apartment
Install a wireless interconnected smoke detector at those locations, and let them connect between the house and apartment wirelessly.


Kidde wireless interconnected detectors can be installed in any combination of 120v or battery powered, and the 120v units have an interconnect lead to connect them to standard wired units, so they can all work together without running a wire between house and apartment

http://www.amazon.com/Kidde-1279-9999-RF-SM-AC-Hardwire-Interconnectable/dp/B000HYL3PA

If you ever want them separated, you just change the wireless code so they don't talk to each other

I've used them in combinations before, where I was required to add smokes in a 2 story house with a finished basement (HUD foreclosure job). The wireless signal works between floors with no problem, up to about 50 feet if I remember right
 
Last edited:

mgookin

Senior Member
Location
Fort Myers, FL
I am pretty certain a wireless unit is not allowed with new construction. The entire house was gutted
Let's reassess this situation:
Building (out) a duplex calling it new construction.
Each will have dedicated electric service.
Desire to have smoke detector system in each unit to send some sort of signal to the other unit - makes sense with elder family member in the other unit.

Idea:
Meet the 1&2 Family code by installing dedicated wired detector system in each unit. At the end of each "chain" of smokes, install a wireless device and have that send wireless signal to a single device centrally located in the other unit, but this wireless device in the other unit not connected to the chain in the receiving unit. This means you need four wireless devices, two in each unit, and you'll need to use two different programming codes. Certainly you're allowed to have wireless devices which are not required because you already met code with the wired system in each unit.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Let's reassess this situation:
Building (out) a duplex calling it new construction.
Each will have dedicated electric service.
Desire to have smoke detector system in each unit to send some sort of signal to the other unit - makes sense with elder family member in the other unit.

Idea:
Meet the 1&2 Family code by installing dedicated wired detector system in each unit. At the end of each "chain" of smokes, install a wireless device and have that send wireless signal to a single device centrally located in the other unit, but this wireless device in the other unit not connected to the chain in the receiving unit. This means you need four wireless devices, two in each unit, and you'll need to use two different programming codes. Certainly you're allowed to have wireless devices which are not required because you already met code with the wired system in each unit.

Yes I actually thought about that after my last post. I will have to see if the home owner wants to pay the expense of that. TY
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Ahhh, sorry, in this case it is prohibited by NFPA 72 and IIRC the IBC as well. A low voltage system is the answer.
I agree, if you go with the standard 120 volt devices they cannot be interconnecting between multiple dwellings.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Simple solution. Wire it with three wire, fed from the central dwelling. Be sure to route the 14-3 to the basement last.

When/if they separate the units, cap the red conductor from above at the first smoke of the divided dwelling unit, still serving 120VAC from the unit above. The only question mark would be access to OCPD for the smokes for the basement dweller, which is likely very easy to deal with.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Simple solution. Wire it with three wire, fed from the central dwelling. Be sure to route the 14-3 to the basement last.

When/if they separate the units, cap the red conductor from above at the first smoke of the divided dwelling unit, still serving 120VAC from the unit above. The only question mark would be access to OCPD for the smokes for the basement dweller, which is likely very easy to deal with.

The units will be separately metered from the start. There was no talk of doing it later so your option will not work. How could you feed one apt from the other and be compliant? Even if the meter were added later I would have to get another feed from the apt in the box.
 

GerryB

Senior Member
The units will be separately metered from the start. There was no talk of doing it later so your option will not work. How could you feed one apt from the other and be compliant? Even if the meter were added later I would have to get another feed from the apt in the box.
The interconnect wire is just a signal wire correct? In our CEU class a year or 2 ago the question came up about interconnecting installed smokes that were not interconnected. The instructor said technically you could run a single conductor to each smoke to connect them. In this case couldn't you feed the in law smokes from their meter and the main dwelling from their meter and still run the interconnect wire?
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
How would the service disconnect for the apt disconnect the branch circuit to the smoke detector. The service disconnect would no longer disconnect all ungrounded circuits in the apt.
By grouping the service disconnects? 230.72(A).

The tenant would need access to the branch circuit OCPD per 240.21(B) - but that does not immediately and completely disqualify feeding Tenant B's smokes from Tenant A. Tenant B would simply need access. An outdoor panelboard or a common garage would solve that.
 
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