bathroom rewiring

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Old 07-09-08, 11:41 AM
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bathroom rewiring

As I'll have walls open for tiling and minor plumbing, I want to take this opportunity to bring my bathrooms' electrical up to code. I'm pretty sure I understand the rules/best practices, but I want to check. I'm in Sunnyvale, California.

1.) I can have one dedicated circuit to each bathroom, right? So the lights, plugs, and vent can all be on one 20A circuit so long as that circuit does not have anything else on it, right? (I realize this isn't the only option, but it seems easiest to me at this point.)

2.) I have to have enough receptacles such that any given point on the counter along the wall is no more than 2 feet from one, right? So if I have a 7 foot counter, I'm going to need two receptacles in the "backsplash" area, at 25% and 75% of the way across, right? Or one at each end and one in the middle? And no other plugs, like along the walls near the floor, are necessary/advisable in the bathroom, right?

3.) Since right now there are other things on the circuits that go through the bathroom (to put it mildly), I need to splice cables together as I remove bathroom items from those circuits. This needs to happen in a junction box that is accessible. I have an unfinished attic that is barely big enough to crawl around in and has no lighting - this still satisfies the "accessible" rule, right? I don't need to have a bunch of blank faceplates in my bathroom, right - I can just put these junction boxes in the attic attached to ceiling joists, right? (I'll staple all the cables to joists/etc in the attic.)

4.) My plan for wiring:
20A breaker => light_1 => gfci plug => plug => vent => switch for vent fan. And then light_1 => lightswitch, and also light_1 => light_2 => ... So this light_1 will have 4 cables coming out of it's junction box. (Pretty sure the shower vent needs to be GFCI protected.)

5.) The light switch should be one of those motion-sensor/timer ones if I'm using incandescent lights.

Thanks very much for any advice or comments. Or suggestions to hire an electrician.

-Erik
 
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Old 07-09-08, 12:27 PM
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1) Correct.

2) That's only for kitchens. For bathrooms, the only requirement is that you must have at least one receptacle within 3' of the edge of the sink. You may have as many others as you wish.

3) The attic is considered accessible.

4) Sounds fine to me. Usually GFCI is only required for the fan if it is located directly over the shower stall. Refer to the installation instructions for the fan.

5) That is not in any National code, but I believe that is true for California.
 
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Old 07-09-08, 12:53 PM
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Originally Posted by ibpooks View Post
2) That's only for kitchens. For bathrooms, the only requirement is that you must have at least one receptacle within 3' of the edge of the sink. You may have as many others as you wish.
And if 2 sinks, then is it within 3' of each? If so it sounds like I might be ok with one plug at either end of the vanity, which seems best from a convenience perspective as well.

Originally Posted by ibpooks View Post
4) Sounds fine to me. Usually GFCI is only required for the fan if it is located directly over the shower stall. Refer to the installation instructions for the fan.
Yeah, that's what it says. They're pretty close, maybe partially over the stalls, I'll just hook them up that way to be safe.

Originally Posted by ibpooks View Post

5) That is not in any National code, but I believe that is true for California.
Ah, yeah, I think I saw it on the city's website, I assume it's a power-saving thing.

thank you sir!
-Erik
 
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Old 07-09-08, 01:16 PM
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Originally Posted by ErikCHaugen View Post
And if 2 sinks, then is it within 3' of each?
Yes, within 3' of each basin. One receptacle could satisfy both sinks if located between the two, but I suspect most people would want a receptacle for each sink.
 
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Old 07-21-08, 04:46 PM
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If I use metal boxes for the plugs and switches, then I need romex connectors to clamp the romex to the box, right? What about the plastic boxes? Is there a similar device for those, or do you just poke one of those perforated holes out and pull the romex through those?
 
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Old 07-22-08, 09:00 AM
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Originally Posted by ErikCHaugen View Post
If I use metal boxes for the plugs and switches, then I need romex connectors to clamp the romex to the box, right?
There are metal boxes with built-in romex clamps in the back or with 1/2" knockouts you can install a clamp in; look around in the electrical aisle and you will see both kinds.

If you do use metal boxes, also pick up some green box grounding screws or grounding pigtail assemblies, because your grounds will need to be bonded to the box.

or do you just poke one of those perforated holes out and pull the romex through those?
Yep. When you push the romex through the hole the springy plastic "jaws" keep it from pulling out.
 
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Old 07-22-08, 02:28 PM
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Thanks for your help!

Unfortunately my wall is not built with 2x4's, but 2x3's or something - some of the walls in my house are thin. I want a 3 gang box for my light switch, fan switch, and plug. But they don't make 'old work' 3 gang boxes that are shallow enough to fit in my walls. Is it ok to get a 'new work' box and cut off the nail fins/etc and drill new holes through the side and into the stud, so I don't need to remove any extra wallboard? This seems easier, but I am wondering if it's ok to improvise like this or if everything needs to be used as the manufacturer intended.

thanks,
Erik
 
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Old 07-22-08, 03:04 PM
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No, you can't alter the box.

You can buy 2" deep gangable steel boxes, which are designed to hook together modular, then mount them into the wall with retaining clips. I can't find a picture of the retaining straps, but they are sheet metal in an "F" shape which you insert beside the box and bend around to the inside to hold the box in place.

 

Last edited by ibpooks; 07-22-08 at 03:20 PM. Reason: Pictures!!
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Old 07-22-08, 04:50 PM
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I could not find out how deep these were, but here is a listed version of what you proposed.
 
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Old 07-22-08, 11:12 PM
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Thanks ibpooks - they have 2 1/2 " gangable "old work" metal boxes with the screw tabs on the sides - if I gang 3 of those together do I still need retaining clips? If so, I can't figure out what to do with them.
 
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Old 07-23-08, 05:07 AM
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They make those boxes with side brackets for new construction. The F clips are for old work.

If you could you would have more room if you could get those 3" deep, 2 1/2 for the stud plus the 1/2" for drywall. You would need to cut the clamp screws so they don't punch through the other side of the wall. You could use cable clamps into 1/2" knockouts and avoid that.
 
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Old 07-23-08, 09:27 AM
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Originally Posted by ErikCHaugen View Post
if I gang 3 of those together do I still need retaining clips?
No, the built-in screw clips are sufficient.

If so, I can't figure out what to do with them.
It's a bit hard to describe spatially, but I'll give it a shot. Once the box is in the wall, the ears on the top and bottom prevent it from going in too deep. You hold the F-support vertically as pictured, then insert the long end between the box and drywall on the side of the box. Slide it all the way in, and you should be able to push the bottom of the F-support into the wall also so the only parts sticking out are the two prongs of the "F". Then slide it down so it's firmly engaged against the drywall and you shouldn't be able to pull it out. You then hold the box tight to the wall and bend the prongs around the face of the box and into it so it will hold in the drywall.

It's one of those things that once you see someone do it once, it makes prefect sense.
 
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Old 08-05-08, 09:35 AM
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Originally Posted by ibpooks View Post
It's a bit hard to describe spatially, but I'll give it a shot. Once the box is in the wall, the ears on the top and bottom prevent it from going in too deep. You hold the F-support vertically as pictured, then insert the long end between the box and drywall on the side of the box. Slide it all the way in, and you should be able to push the bottom of the F-support into the wall also so the only parts sticking out are the two prongs of the "F". Then slide it down so it's firmly engaged against the drywall and you shouldn't be able to pull it out. You then hold the box tight to the wall and bend the prongs around the face of the box and into it so it will hold in the drywall.

It's one of those things that once you see someone do it once, it makes prefect sense.
I feel like I've seen you do it now, thanks!

-Erik
 
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Old 08-05-08, 09:34 PM
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Originally Posted by ErikCHaugen View Post
... So this light_1 will have 4 cables coming out of it's junction box
-Erik
Make sure this junction box is big enough for all those 12 AWG wires.

If you use metal w/ the internal romex clamps that you screw to make them tight to the back of the box, you need a minimum box volume of 24.75 cu. inches (and none of the round or octagonal metal boxes are big enough - must use square). Some choices are:
-- 4" square x 2-1/8 deep (has 30.3 cu. in.)
-- 4-11/16" square x 1-1/4" deep, 1-1/2" deep, or 2-1/8" deep are all even larger = OK.

If you use metal w/ external romex clamps that attach w/ a locknut, OR a plastic box, you need 22.50 cu. in of volume. However, it just so happens that the above list of metal boxes are the only metal boxes that fit this volume (and still none of the round or octagonal metal boxes are big enough). For a plastic box, the volume is molded into the inside of the box.

You'll be glad that you will be in compliance with box fill requirements and that you'll have plenty of room to fit your conductors without stuffing them in with a hammer.

willis (the box fill cop )
 
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