Metal vs Plastic Electrical boxes.

[Doc]

When should you use metal and when is it okay to use plastic electrical boxes?

I think I should use a metal junction box for wiring up 4 switches, but wanted to double check before I do the install. I plan to run one hot wire to the junction box and come out with 4 wires for four switches. Would that be okay and 'up to code' in most places?

[OhioTC18]

Plastic is always easier to work with. A 4-gang plastic switch box is about the biggest "commonly available" size you'll find.
A typical 4-gang switch box with 5 cables should be okay. Almost all plastic boxes have the number of conductors allowed printed inside the box.

edit to add......... Metal boxes must be used with a metallic wiring method, but if you're using a plastic jacketed cable such as NM-B cable (commonly called Romex) a plastic box is what I would use.

[AAUTOFAB1]

ummm,what Gage wire is your home run and what amp breaker are you going to use? maybe a 3 wire home run with 12ga wire going to a 20 amp two poll breaker ?
i only use metal boxes for junctions, but local codes may be different .

[Doc]

12 ga wire throughout the house. I'm using 12/2.

I plan to use two double swith boxes one stud apart from each other, but one junction box for all the power wires before they jump to the switch boxes (sorry I don't know the right terminology for this stuff). I am useing romex wire so I guess I can use plastic all the way around. :thumb: Thanks guys!!!

[OhioTC18]

I would forget the junction box, but that's just me. Feed into one 2-gang and feed out to the other. Then two switch legs out of both of the 2-gang boxes.

[FrancSevin]

12 ga wire throughout the house. I'm using 12/2.

I plan to use two double swith boxes one stud apart from each other, but one junction box for all the power wires before they jump to the switch boxes (sorry I don't know the right terminology for this stuff). I am useing romex wire so I guess I can use plastic all the way around. :thumb: Thanks guys!!!

Yeah, skip the junction box if you can. One cannot bury a juntion box in the wall. It has to be accessable. So, if you use one you have to have a surface mounted access cover.

Use deeper plastic boxes for the switches and plugs. Do your distribuion connections behind that appliance and then you aren't covering the wire junctions behind drywall.

I'm pretty sure that is code in most places. And it is just good practice.

Plastic boxesare morethan fine. Just be sure you secure the Romex well to the wallstud and within a few inches of the box. (six inches I think)

[Doc]

I would forget the junction box, but that's just me. Feed into one 2-gang and feed out to the other. Then two switch legs out of both of the 2-gang boxes.
Does anyone have diagrams of what you are talking about. Not sure if junction boxes was the right word vs gang box etc.

My power source is about 20 feet away and I wanted to run one wire to right above where I need the switches and then splice off from there to each switch. Good idea or not?

[FrancSevin]

Does anyone have diagrams of what you are talking about. Not sure if junction boxes was the right word vs gang box etc.

My power source is about 20 feet away and I wanted to run one wire to right above where I need the switches and then splice off from there to each switch. Good idea or not?

Skip the juctin box and just bring the pwoer wire intothe firs switchbox. go ourfrom there to the light fixture and add jumpers over to the next switch & light wire. Run the black thru the switches and the white straight to the appliance (light fixture) White to white, black to black, ground to ground tying them all together.

It may seem simpler to distribute from a junction box but as I said earlier, that is problematic.

[OhioTC18]

Franc pretty much said what I was was talking about. It's not all that easy to draw it out on here, maybe I can do one in MS Paint tomorrow morning

[TiredRetired]

When should you use metal and when is it okay to use plastic electrical boxes?

I think I should use a metal junction box for wiring up 4 switches, but wanted to double check before I do the install. I plan to run one hot wire to the junction box and come out with 4 wires for four switches. Would that be okay and 'up to code' in most places?

You can use plastic for 4 gang if you can find one. Electrical Wholesaler should have them. Otherwise just use the gangables. Go with the deep ones.

One hot wire to feed the four switches should be OK.

Metal boxes are required if running MC cable. Maybe they have an approved plastic box for MC that would have metal straps to continue the ground continuity between the KO's but it would prolly be more money than what it is worth.

Plastic boxes and romex are made for each other.

Always, always use a metal box for a ceiling fan.

Don't get bit.

[TiredRetired]

I would forget the junction box, but that's just me. Feed into one 2-gang and feed out to the other. Then two switch legs out of both of the 2-gang boxes.

Yup. What Ohio & Franc said. I just noticed these posts. :biggrin:

[OhioTC18]

Always, always use a metal box for a ceiling fan.


There are several plastic boxes listed for use with a ceiling fan and are safe to use for that application.

[TiredRetired]

There are several plastic boxes listed for use with a ceiling fan and are safe to use for that application.

Really? Well there you go. All my years in the trade I stayed away from wiring houses like the plague except my own. Now that I retire from the trade I just learned something. My next trip to the wholesalers for my remodeling project I will check it out. Thanx! :biggrin:

[OhioTC18]

I've used 3 in my house and one in my son's house.

[Doc]

Like this:

[TiredRetired]

Yup, you got it.

[Doc]

I found that diagram elsewhere but it fits.

I would have four switches but from what you all have said four is ok, just as three would be.

Thanks all.

[TiredRetired]

I found that diagram elsewhere but it fits.

I would have four switches but from what you all have said four is ok, just as three would be.

Thanks all.

From what I can see of your intentions you will not have enough load to even come close to maxing out a 20A branch circuit. 4 switches will be fine on one circuit. A good guideline is not to max a circuit out more than 80% of it's rated capacity. In other words, 16A max on the 20A circuit. This allows a safety margin. It is not in the NEC, however, so it is not the law, just a good common sense practice to keep things kosher.

[OhioTC18]

Yes that would work but still looks like you use a junction box. If you want to and it's accessible then by all means do that.

[muleman]

If you don't already have the wire you can use 14-2 for all the switched circuits. Run 12 to the first supply. 14 is a hell of a lot easier to work with and will handle anything a single pole switch will unless it is a 20 amp commercial switch. You should Buchannon splice all your grounds so they are tight.

[OhioTC18]

If you don't already have the wire you can use 14-2 for all the switched circuits. Run 12 to the first supply. 14 is a hell of a lot easier to work with and will handle anything a single pole switch will unless it is a 20 amp commercial switch. You should Buchannon splice all your grounds so they are tight.
Sorry muleman you can't mix the two sizes unless you have the breaker at the size for the smallest wire.

[muleman]

Sorry muleman you can't mix the two sizes unless you have the breaker at the size for the smallest wire.
You are 100% right on that. Should only be a 15 amp. That will handle anything that is not heating something or running a motor.

[jim slagle]

Doc, just for the record, you can purchase non-metalic junction box/enclosures large enough to live in. :whistling:

We used Crouse Hinds enclosures, fiberglass most places and their aluminum boxes with screw on lids in hazardous atmospheres.

Jim

[Doc]

Why does a junction box need to be easily accessible? I was going to put it above the switch boxes but behind the drywall.

[OhioTC18]

Why does a junction box need to be easily accessible? I was going to put it above the switch boxes but behind the drywall.That's a no no

[muleman]

Those NEC requirements came about because folks used make splices with just tape or maybe wire nuts and cover them up inside the walls. Bad connection starts a fire and take a place down quick. Or they splice in extension cords etc. and hide it.

[FrancSevin]

Why does a junction box need to be easily accessible? I was going to put it above the switch boxes but behind the drywall.

A lot of heat can build up inthe box. Evertime the circut is used the wires heat up and then cool down. Eventualy the connections come loose and then arcing begins.
If this happens in an appliance box, say a duplex wall plug or a light switch, you can usualy seeit, smell it, sense it, and because you can get to it, you can fix it. A closed junction box in the wall is inaccesable. You won't see it, smell it or sense it going bad. The circut may just go dead or it'll just burn the house down.

Neither is a good outcome.

If you are stuck on using a junction box, you can do a junction box in the attic, or an open exposed floor joist system, and then come down into the wall.

Just remember,every connection cuts voltage and is a possible failure point in the circut.

[FrancSevin]

Like this:

Doc, the only thing I see missing is ground fault interuption. Code requires it in all bathrooms and kitchens as a minimum. I use them everywhere.
One $ 8.00 plug will save your house or maybe your life.

Run your incoming power to a GFI wall plug set in a deep box. You could use the deep box as your "junction box" Then go to your switches

Of course GFI implies the proper grounding throughout the circuts. Be sure all the gound wire connections are secured with a screw ( just go right to the box, Plasitc or Metal) or or spliced properly.
Buchannon splices
http://www.hudsonfasteners.com/wire_nut/wire_nut_images/wn_buc_spcap_crimp.jpg

[TiredRetired]

Code requires that the junction box be "readily accessable. That means it is OK to be behind behind a wall if you have an access panel to get to it or above a ceiling as long as it has removable ceiling tiles. I have one behind a knee wall that i can get to on my hands and knees. Readily accessable does not necessarily translate to easy. It is just you do not want them where you would have to remove sheetrock or paneling or whatever to get to it. That would be a NEC violation anywhere in the country. A real rookie mistake. No offense.

Besides, just bring your 12/2 romex feed directly into your 4 gang box you are using to mount your switches into. Pig tail off of the feed to your 4 switches. Now all 4 of your switches are fed. Then branch out to your 4 switched lights with the four romexs. East as pie. :biggrin:

[JEV]

Code requires that the junction box be "readily accessable. That means it is OK to be behind behind a wall if you have an access panel to get to it or above a ceiling as long as it has removable ceiling tiles. I have one behind a knee wall that i can get to on my hands and knees. Readily accessable does not necessarily translate to easy. It is just you do not want them where you would have to remove sheetrock or paneling or whatever to get to it. That would be a NEC violation anywhere in the country. A real rookie mistake. No offense.

Besides, just bring your 12/2 romex feed directly into your 4 gang box you are using to mount your switches into. Pig tail off of the feed to your 4 switches. Now all 4 of your switches are fed. Then branch out to your 4 switched lights with the four romexs. East as pie. :biggrin: I concur with TR. No need for a junction box, as you'll just be making more work for yourself in the long run. The 4-gang box at Home depot is $3.74 and the specs are here (http://www.homedepot.com/h_d1/N-5yc1v/R-100404086/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=4-gang+plastic+junction+box&storeId=10051&superSkuId=202891080). Accessibility means that with a finished wall, you must have a removable cover plate to access the wire junction/splice. Also, be sure all pigtails extend 6" minimum to meet NEC requirements. This makes wire management and device connects easier, and even though you have more wire, it folds back on itself neater than stubby leads. Some people think they are saving money by leaving just enough wire to connect the device(s), when in fact the opposite is true. I curse homeowners who do their own wiring where I can barely attach wires to the device when changing devices, and who use shallow boxes to save pennies per box. Penny wise, pound foolish, and they should not be allowed to breed, IMHO.

Your ceiling fan should be mounted to an appropriate box-brace assembly that will support up to 50#, which accommodates most ceiling fans in residential application. This one (http://www.homedepot.com/h_d1/N-5yc1v/R-202049572/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=ceiling+fan+electrical+box&storeId=10051) will handle 150# at 16" on center, or 50# when joist are on 24" centers, and is all steel construction...no plastic. It's cheap insurance to make sure the fan does no fall from its mount, and I use them in remodel applications all the time, when there is not an approved box to mount the fan/light combo on. If you are going to control the fan and light each on their own switch, you will need a length of 12-3/with ground wire for a single cable run from the switch box to the fan/light combo mounting box. This is the recommended installation for fans that are not controlled by a remote sensing device. Fan/lights with remote sensing only require the 12-2/with ground non metallic cable (Romex). If using one of these remote sensor fans, then only 3 switches are required. The downside of these remote sensing fan/light combos is losing the remote console and battery failure.

Please take no offense at this comment...if you have to ask how to do an electrical project, you should not attempt to do it without supervision from a licensed electrical contractor. Seek out one and pay a "consulting fee" if necessary to insure you are doing it properly. From what you are describing, this is a project that "most" communities would require a permit for, and the permitting process requires a drawing/schematic that is approved by the inspecting authority PRIOR to the work being done. You will get a "rough inspection" when the boxes and rough wiring are installed, and a "final inspection" at the end of the job when the inspector will test your devices to insure polarity, grounds and Ground Fault Circuit Interrupters (GFCI) where applicable (determined at drawing approval), and that you have wired the circuit into the panel properly. Electrical wiring is a Life Safety issue that should not be taken lightly. You might be surprised at how much you will save hiring a professional, vs paying one to come and redo what you have already done.

Just my 2 cents worth fro a guy who does this stuff for a living.

[TiredRetired]

Everything Joe said. I could not have said that better myself. :biggrin: If one were to zoom in on that fan box from Home Cheapo one would see that a junction box made specifically for a fan installation has mounting studs for the 8-32 screws as well as the two standard 8-32 mounting tabs. One would want to make sure they use the studs in lieu of the tabs in order to get that 150# ratings. Using the standard tabs will only give you one or two threads for the 8-32 screws and that is not enough. Common sense stuff most would figure out anyway but you would be surprised.

As Joe also mentioned, it is extremely important and worth mentioning again to leave the wires long enough out of the boxes to the device being terminated. The 6 inches required by code sure facilitates the folding of the wires back onto themselves and makes tucking them into the box when trimming off much much easier. A rookie mistake is in thinking the shorter the wires, the less to fit into the box but in this instance that is not the case.

One point Joe did not touch upon is the size of the boxes. USE DEEP BOXES. I use only the 3 1/4" deep ones.

Happy wiring!

Good thread guys.

[Doc]

Thanks guys. No offense taken Joe. I am a rookie at this for sure. I am leaving plenty of wire length so that I was worried about getting it all back into the box. Deep boxes sound like a good idea, and how I can accomplish the 4 gang switch. It seemed as it would be so crowded in the box for all the wires I thought for sure I had to have a junction box. Good to know that is not the case and how to get around that.

I have already run the circuit for the receptacles. A GFCI outlet will be the first in the string. I am working on this slowly, as I have time and when the weather keeps me away from boating. Slow but sure I'll get er done.

I am out in the sticks. No inspections or anything like that required. Joe, if you want to deliver some cinnabuns I'd be happy to have you inspect and assist while you are here. :yum: :yankchain: Really, I do wish you were closer. That would be nice.