Coppersmith
Senior Member
- Location
- Tampa, FL, USA
- Occupation
- Electrical Contractor
I saw a news story about clusters of tiny houses (94 sq ft). The individual units had no kitchen or bathroom. There is a common kitchen and bathroom building. These are in Colorado and are used to house the homeless. It got me thinking about how I would wire such a place.
Each of the individual tiny houses had interior receptacles and built-in lighting, a porch light, and an external receptacle. I saw a window a/c unit. They are in a cold climate so I’m going to assume they either have heaters in the a/c units or separate space heaters. One resident said he had a fridge. (I assume a dorm sized one.)
Cost was a major factor, so what is the least costly way to wire these units? Here is what I thought. Each unit has two 20 amp circuits. One dedicated circuit for the a/c and heat and one circuit for everything else. These circuits terminate in a two slot interior panel. The panel is fed with 120v (not 240v) so the two split phase sides are jumpered. Having a panel on each unit allows the residents to control their own breakers in case of overload. Conduit runs from the panel to under the unit crawl space and into a junction box. This is where the feeder would be attached.
One or more central common meters feed main distribution panels with a one pole 40 amp breaker* for each housing unit. Underground feeders feed each unit. Since it’s a 120v feed, only one hot wire is required (a cost savings in wire and conduit). The main distribution panel can be locked to avoid residents turning off a neighbor’s power. The residents pay rent. Due to the nature of the place, I’m assuming the organization running the place would provide the electricity as part of rent.
A common 200 amp service could handle 5 or 6 units. A common 320 amp service (with two 200 amp panels) could handle 8 to 10. The largest cluster I read about was 14 units plus the common building.
* I saw a post a week or so back about single pole 40, 50, and 60 amp breakers being available and what you would use one for. Here is an example.
Each of the individual tiny houses had interior receptacles and built-in lighting, a porch light, and an external receptacle. I saw a window a/c unit. They are in a cold climate so I’m going to assume they either have heaters in the a/c units or separate space heaters. One resident said he had a fridge. (I assume a dorm sized one.)
Cost was a major factor, so what is the least costly way to wire these units? Here is what I thought. Each unit has two 20 amp circuits. One dedicated circuit for the a/c and heat and one circuit for everything else. These circuits terminate in a two slot interior panel. The panel is fed with 120v (not 240v) so the two split phase sides are jumpered. Having a panel on each unit allows the residents to control their own breakers in case of overload. Conduit runs from the panel to under the unit crawl space and into a junction box. This is where the feeder would be attached.
One or more central common meters feed main distribution panels with a one pole 40 amp breaker* for each housing unit. Underground feeders feed each unit. Since it’s a 120v feed, only one hot wire is required (a cost savings in wire and conduit). The main distribution panel can be locked to avoid residents turning off a neighbor’s power. The residents pay rent. Due to the nature of the place, I’m assuming the organization running the place would provide the electricity as part of rent.
A common 200 amp service could handle 5 or 6 units. A common 320 amp service (with two 200 amp panels) could handle 8 to 10. The largest cluster I read about was 14 units plus the common building.
* I saw a post a week or so back about single pole 40, 50, and 60 amp breakers being available and what you would use one for. Here is an example.
