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Wiring help & NEC compliance with detached garage converted in-home child care.

Wiring help & NEC compliance with detached garage converted in-home child care.


  #1  
Old 12-14-20, 02:34 PM
J
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Wiring help & NEC compliance with detached garage converted in-home child care.

Greetings,

My girlfriend runs an in-home childcare operation. She has a large detached garage that I am converting into a space for her to continue doing so. The garage is 20'x30' and has a large attic space we may eventually use as well. No rush on that possibility in any way. I am fairly new to all things electrical, but have been doing my homework and feel confident I can tackle such a simple job. I am concerned with being NEC compliant and and probably will have some basic questions as this discussion unfolds. Thank you SO much for any help you provide. I am on a timeline to get her operational again, and I am at a stopping point with construction until I knock out electrical.

Here's some initial questions:

1) According to ye ole google:

"A significant change to the 2017 NEC that will affect new garage wiring is NEC 210.11(C)(4), this section requires the receptacles in a garage to be supplied by a 20 amp branch circuit by themselves, no other outlets. This change will require, at minimum, a multi- wire branch circuit to a new detached garage."

What I'm hearing here is that a detached garage needs a dedicated 20 amp branch circuit for the outlets alone. But does this apply now that I'm converting it into a heated space for childcare? If not... great. If so, it seems that I should run three (3) separate circuits from the house underground to the space:
-a 20amp one for all outlets
-a 20amp one for all lights
-and a 20amp one for potential use eventually in the attic for lights and outlets.

Is this correct? HOWEVER... if we ever did finish the attic, perhaps this means I should simply send a wire up there that's connected to the main floor outlets and thus will comply with the code I mentioned needing all outlets in a detached garage to be on one dedicated 20 amp circuit. Perhaps I shouldn't do this... in case too much power is used at once (this is doubtful as her power needs will be minimal regardless if there was an upstairs and a downstairs room). If I did this would this mean I should then just connect the lighting circuit from downstairs to the upstairs as well? If I did so I would then basically only have two separate circuits:
-a 20amp one for ALL (upstairs and downstairs) outlets.
-and a 20 amp one for ALL (upstairs and downstairs) lights.

2) Regardless if I use 2 or 3 different branch circuits from the house, can all circuits simply meet in a junction box and then divide up, or am I required by NEC code to have some other sort of "box" for them to meet at?

3) All wires will leave the house and enter into conduit and go down 2' into the ground, run across the yard, and then back up conduit into the garage. Is there a particular type of conduit that is required by NEC code? I heard something about "80" conduit, which I think refers to 80mm. Also, is it unwise to use underground rated wires and simply run them 2' under ground after coming in and out of the conduit at both ends? Is it required by code that I use conduit the entire way under ground?

4) I think I've figured out how to wire the lights using 3-way wire (12-3) so that I can operate any and all of the light switches from two different locations. I am interested in using dimmer switches and also in in installing one or two fans with a couple of the lights. Will I need to run addition wire or some other sort of wire to do so or will my plans to run everything with 12-2 wire (except for the additional 2 lengths of 12-3 wire running both ways from the switches) be enough to accommodate dimmer switches and fans as well?

5) Some pretty basic question on all things outlet and switch boxes. Does it matter what size or type box I use really? Are they not all simply boxes where wires run into them and outlets or switches can be attached and the most important thing is if you need a larger size to accommodate more switches, dimmer switches, etc? At the hardware store there are SO many different sizes and some are plastic, some are metal. Does any of this matter?

6) What's the deal with needing receptacles to be AFCI receptacles as well as TR (tamper resistant)? Since this is in the code are all designed that way and there is no worry of buying the wrong ones? I see also that circuit breakers need to be AFCI breakers as well. Are they all simply made this way now?

7) I REALLY want to make sure I am NEC compliant. The only considerations I have found so far that could make me fail an inspection is:
-Making sure I use 20amp circuits and thus 12 gauge wire.
-Have outlets no more than 12ft apart at any point all the way around the walls.
-Making sure all walls over 2ft in width have an outlet.
-This whole thing on receptacles being AFCI and TR (tamper resistant)
-Breakers needing to AFCI

What am I missing here that I haven't considered?


Sincerely... THANKS for any and all help. I want to get this right and to get moving again. Most open to anyone's private help over email as well with all this. I don't know if that's allowed, but if so, I'm down. Gotta keep this project moving!
-Jacob
 
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Old 12-14-20, 02:53 PM
J
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My uncle just let me know that Article 225 requires a service disconnect for a detached garage. Is it possible to complete all the wiring in the building, without putting in a service disconnect, digging the trench to the house, etc... so that I can at least get my interior wiring inspected and move on with the rest of the construction, ie... the ceiling, insulation, drywall, etc?
 
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Old 12-14-20, 02:54 PM
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You can't run three separate circuits to a detached building. You must run one multiwire circuit and install a sub panel. The size of the panel is determined by your loads. Receptacles don't use any power but if you intend have any sort of heat or AC that needs to be considered
After the conversion it seems this not be a garage any long but living space. If the large garage door is closed off that is more of a confirmation of no longer garage
 
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Old 12-14-20, 05:22 PM
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Start with a whole house load analysis for proposed total power usage for house and garage combined. Then do a subpanel load analysis which would cover just the garage. Sample rules for both are at the back of the NEC book. Put in all of the boxes (including the breaker panel, which may or may not have the master disconnect for the building included and at the top. String all of the wiring except for the (probably 6 gauge 50 amp) feed cable from the main house. Dig five feet worth of the trench to the main house. Set up the path (probably conduit) from the garage panel to the start of the trench.
This should be enough to complete the rough inspection for all of the interior wiring and then you can put up the drywell, etc./. You will need to pull a separate permiit to install the cable to the main house because you needed the sign off on the permit for the interior garage wiring. Finish inspection is with the receptacles, switches, light fixtures, etc. installed.

A 120/240 volt feed (hot, hot, neutral, ground) aka multiwire branch circuit is the "standard" way of running more than 20 amps of power to a detached garage.
 
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Old 12-15-20, 06:56 AM
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"A significant change to the 2017 NEC that will affect new garage wiring is NEC 210.11(C)(4), this section requires the receptacles in a garage to be supplied by a 20 amp branch circuit by themselves, no other outlets. This change will require, at minimum, a multi- wire branch circuit to a new detached garage."
But this will no longer be a garage so you can forget the garage requirements. This will just be a detached building. You will need a subpanel in this building. The 2 circuits maximum you can get from one multiwire branch circuit will not be enough. Yes, you will need to do a load calculation in order to determine how many amps to feed the subpanel with.
 
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Old 12-15-20, 10:53 AM
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Agreed with CasualJoe, this is no longer a garage, but a detached building wired like a normal house. So you'll need receptacles and lighting like you would in a house. Do you need heat/AC in this space? Is there a kitchen/prep space? Bathroom? All have their own requirements that you'll have to meet.

In a nutshell, you'll need to run a 30/40/60/100A feed (4-wire) to the building (depending on the load requirements). Subpanel and a ground rod at the building. Then out to the circuits which may need to be AFCI depending on your locale's code cycle.

The other option if the building is small and just needs some basic receptacles/lighting, you can run a 12/3 cable as a multi-wire branch circuit and get yourself two 20A circuits at the building, no subpanel required. But obviously this probably won't be enough if you have a bathroom, kitchen, hvac, etc.
 
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  #7  
Old 12-16-20, 02:49 AM
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My suggestion is for you not to do any of the electrical. The reason why I say this is because it sounds like you are in over your head on this. Some of the questions you ask are simple basic knowledge for an electrician. You can't just Google and then feel you can wire an entire building to code. There is far too much more to consider as even some of the responses have already told you.

The simple fact of running multiple circuits to an unattached building would have failed the inspection before it even really started.

You think you will be saving her money by doing this yourself but in fact it sounds like it will end up costing her far more when you realize you hit a stone wall and can't finish the job yourself. She will have spent all that money on materials etc at that point. Finding an electrician to finish where you left off will be almost impossible to do. Any licensed electrician will not want to take the liability of your work on their insurance. An electrician will probably rip your materials out and start all over again. I am not trying to put you down but this is a good size project and too many things can go wrong. Planning this out is not as simple as you may think.

As mentioned you should do a load calculation. This will determine what your power needs will be overall and what upgrades you may have to end up doing with the main service even. You never mentioned heat. I assume you are in an area where it gets cold. I hope space heaters were not planned for this building as a main source of heat.

You really have to give this far more thought towards having a professional do it. Especially since kids are involved especially ones that are not her's.


 
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