15 amp vs 20 amp circuit planning

Old 08-16-04, 10:18 AM
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15 amp vs 20 amp circuit planning

Hi, I am designing a new building (a yurt, actually, visit http://www.chriscouture.us/yippee/ if interested) and am doing the circuit diagram myself. I have a basic understanding of electric work, enough so that I can do this part and then share it with a pro to make sure I'm not designing a death-trap

Anyway, I have a two part question:

1) I have a number of 20amp circuits. Kitchen & laundry in particular. We are not building big, so there aren't many circuits. I am wondering if, for lighter duty items, it matters whether we use a 15 or 20 amp circuit. I thought I might be able to stack some lights in the 20 amp circuit for the washer, for example. If I could safely wire the entire place with 20 amp circuits ( for the 120v, naturally) and skip 15amp entirely, it seems a good idea.

2) Following that thought, can I have a 15amp circuit in the bathroom? I've seen 15amp GFCI and the only reason I'd need a 20amp circuit in there would be for that GFCI, if 15a wouldn't work. We only have a light and an exhaust fan in there now, both can run on 15a.

Old 08-16-04, 10:28 AM
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There are some rules that you have to follow.
Regardless of size, a kitchen has to have 2 20A circuits for the coutertop receptacles (plus probably another one for the fridge, dishwasher, disposer, etc). A laundry room has to have its own dedicated 20A circuit. A bathroom also has to have its own 20A dedicated circuit. There are also rules on outlet locations (spacing between them). I don't do this every day so I don't remember all rules...

When I do inside wiring I run a 20A circuit to every bedroom in the house. The living rooms gets 2 circuits, one for the entertainment center and one general duty. The kitchen usually gets 4 or 5 circuits (coutertop, fridge, dishwasher, etc). Don't forget about the AFCI outlets (if the local jurisdiction requires them in the bedrooms), smoke detectors, etc).

The biggest reason why you don't want a 15A circuit in the bathroom is not the light/fan combo, but the hair dryer. A 1500W unit will probably trip the breaker if the lights and fan are on at the same time. 15A = 1800W total, but you can only "use" 80% of that, which is 1440W.
Old 08-16-04, 10:58 AM
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The 80 percent rule for dwellings is not important, except perhaps for dedicated circuits.

Your kitchen will require at least two 20 amp GFCI circuits for the countertop. Plan on other circuits for the refrigerator, stove, dishwasher and disposal. Lighting for a kitchen is another cirucit, although the lighting can be shared with another room.

You need either one 20 amp circuit for each bathroom or you need one 20 amp circuit for the bathroom recepticles and can have all bathrooms on this circuit, with the lights going on another circuit which can be shared.

You need a 20 amp dedicated circuit for the laundry. Even if you don't have a dedicated laundry room, you still need a laundry circuit. Run a circuit to the location where you will have the washer and dryer.

There is no reason why you need to include any 15 amp circuits, if you don't want to.
Old 08-16-04, 05:10 PM
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Yurts are fun to wire. Good luck! (Sarcasm, sorry )

Follow the previous advice, very good points.
Since you will have no walls it makes it easier as far as requirements yet harder as far as getting everything required in there.

Yurts, must be a primal thing. I live right near Woodstock, NY, and there are several of them around here.

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