plastic box vs. metal box (electrical)

Author	All Replies
aurgathor join:2002-12-01 Lynnwood, WA	plastic box vs. metal box (electrical) I'll be doing a bit of wiring (i.e. adding 3 way switch and a some extra outlets) and would like to know when to use a metal box vs. a plastic box. TIA -- And the winner is:
	to forum · permalink · · 2009-11-08 19:24:34 ·
John Galt Forward, March Premium join:2004-09-30 Happy Camp	Exposed work or cut-in?
	to forum · permalink · · 2009-11-08 19:33:42 ·
aurgathor join:2002-12-01 Lynnwood, WA	Exposed ATM since I'll be doing the insulation/drywall after the wiring. -- And the winner is:
	to forum · permalink · · 2009-11-08 19:41:05 ·
dgilbert Good Bye My Friend Premium,MVM join:2002-06-15 none clubs:	reply to aurgathor if you use metal, you MUST ground it. if you use plastic you don't. no biggie either way though. whichever you use, make sure you have the proper clamps for the box type and the cable used. -- Lack of Preparation on YOUR Part does NOT Constitute an Emergency on Mine!
	to forum · permalink · · 2009-11-08 19:44:14 ·
John Galt Forward, March Premium join:2004-09-30 Happy Camp ·CenturyLink	reply to aurgathor In residential applications I usually use plastic, unless it is for something specific like the range or other larger conductor applications. Less grounding involved...and far easier with built-in cable clamps. If you treat plastic boxes with reasonable care (meaning don't strip them), they will last a long time. I've had people request all metal, though. They paid for it...time and materials. -- The man who speaks to you of sacrifice is speaking of slaves and masters, and intends to be the master.
	to forum · permalink · · 2009-11-08 21:03:54 ·
nunya SEE ROCK CITY 475 MILES Premium,MVM join:2000-12-23 O Fallon, MO clubs: ·AT&T CallVantage	reply to aurgathor I prefer metal. The hard part is getting customers to pay for it. I like the additional space you get with 4" boxes. However, a 20-22 cu inch plastic box isn't bad either. Typically, residential is plastic and commercial is metal. Although there are a few municipalities that require metal for everything.
	to forum · permalink · · 2009-11-08 21:09:47 ·
Nick_L Premium join:2003-01-22 Pittsburgh, PA	reply to aurgathor the question I have (and hopefully someone can answer) is do plastic boxes have a fire rating as compared to metal. I like to dabble in home automation and use/have used x-10, insteon and now Z-Wave. Z-Wave is a wireless mesh technology so obviously plastic boxes are a benifit in that regard. My concern is that with the switches themselves getting more and more complex and having more and more components, the risk of malfunction and fire becomes much greater. So, do plastic boxes have any kind of fire rating? Thanks, Nick
	to forum · permalink · · 2009-11-08 21:42:24 ·
Msradell join:2008-12-25 Louisville, KY	No, the plastic boxes don't have a fire rating, they are however fire resistant in most cases. That means that they will not free burn when the source of ignition is taken away. However I really wouldn't worry about automation switches bursting into flames. If anything they are probably safer than conventional switches. Anyway if the switch starts burning the box is the least of your problems.
	to forum · permalink · · 2009-11-09 00:05:25 ·
aurgathor join:2002-12-01 Lynnwood, WA ·Verizon west (ex G..	reply to aurgathor I just got back from Lowes, and it's and plastic. And I can fully understand why customers don't want to pay for metal. I figured I'll be using metal for high-amperage and/or exposed boxes, but for most everything, I'll stick to plastic. Thanks to all who replied. -- And the winner is:
	to forum · permalink · · 2009-11-09 00:13:54 ·
whizkid3 Premium,MVM join:2002-02-21 Queens, NY ·Earthlink Cable Mo..	reply to aurgathor The benefit of a metal box is that should a hot wire come into contact with the box, it will short-circuit to ground and trip the circuit breaker, de-energizing the circuit, rather than posing a risk of shock or fire. Plastic boxes generally are for type NM wire only (Romex), meaning that in most localities they can only be used in small residential work (1 & 2 family homes). Although more expensive, I find metal boxes easier to work with. As far as extra work grounding, etc - that is not the case if you work with type-AC or type-MC cable. Its actually less work to use all metal and self-grounding receptacles. There is virtually no grounding work at all. That being said, I prefer metal boxes in all my own work.
	to forum · permalink · · 2009-11-09 00:55:47 ·
brianiscool join:2000-08-16 Miami, FL	reply to aurgathor I prefer a cedar box
	to forum · permalink · · 2009-11-09 04:32:47 ·
evil_gusgus join:2008-04-14 London, ON	reply to aurgathor You arn't allowed to use plastic boxes in Canada for this use. The only time you use them is when their are outdoors. I would recommend that you use metal ones.
	to forum · permalink · · 2009-11-09 05:36:10 ·
LazMan join:2003-03-26 Angus, ON ·TekSavvy Solutions..	said by evil_gusgus : You arn't allowed to use plastic boxes in Canada for this use. The only time you use them is when their are outdoors. I would recommend that you use metal ones. Actually, I'm pretty sure plastic boxes are fine, at least in Ontario... In fact, my Knight book specifically mentions them, as an option, rather then using a metal box and vapour barrier, in exerior walls. That said, I just about always use metal... And to the comments about grounding above, every plastic box I've seen has come with a metal bonding strip in it, that does require grounding.
	to forum · permalink · · 2009-11-09 08:11:46 ·
patcat88 join:2002-04-05 Jamaica, NY 1 edit	reply to whizkid3 said by whizkid3 : The benefit of a metal box is that should a hot wire come into contact with the box, it will short-circuit to ground and trip the circuit breaker, de-energizing the circuit, rather than posing a risk of shock or fire. Plastic boxes generally are for type NM wire only (Romex), meaning that in most localities they can only be used in small residential work (1 & 2 family homes). Although more expensive, I find metal boxes easier to work with. As far as extra work grounding, etc - that is not the case if you work with type-AC or type-MC cable. Its actually less work to use all metal and self-grounding receptacles. There is virtually no grounding work at all. That being said, I prefer metal boxes in all my own work. Metal boxes will oxygen deprive any fire inside them (assuming you have metal faceplate), which is why all commercial and high rise buildings use metal. Metal boxes and MC/AC cable stop oxygen from getting and smoke getting out of the electrical system, especially important in office buildings with suspended ceilings that act as return air ducts. Even with plastic faceplates, fire shooting out the front of the box is better than fire shooting up behind the wall which will take more time to recognize. And the advantage of shorting to ground of metal box and AC/MC cable is a huge safety feature in my opinion. Cockroachs and termites can go inside boxes and start problems. Insects love warm wirenuts. Much better and safer than the AFCIs the industry is now pushing. Only problem with metal electrical systems is extension cords. They rarely have a metal shielded/braid/jacket that a hot wire could arc to and trip the breaker, except for the "fire guard" AFCI extension cords. AC/MC also reduces undetected "nail through the romex" problems. Someone has their siding replaced, the romex gets turned into swiss cheese from the nails
	to forum · permalink · · 2009-11-09 08:27:59 ·
dsless join:2001-05-16 Pittsburgh, PA	reply to John Galt Steel is easy for light switches and receptacles! How about some nice Raco or Steel City stuff!
	to forum · permalink · · 2009-11-09 15:08:27 ·
John Galt Forward, March Premium join:2004-09-30 Happy Camp ·CenturyLink	said by dsless : Steel is easy for light switches and receptacles! How about some nice Raco or Steel City stuff! Yeah, but now you are looking at the cost of the bracket box, two cable connectors (or more), mudring and grounding pigtail. Price THAT and compare it to the cost of a plastic box... Plus the time (expensive) to dink around and assemble that. I can nail up 10 plastic boxes in the time it takes you to put one metal one together. Just saying... -- The man who speaks to you of sacrifice is speaking of slaves and masters, and intends to be the master.
	to forum · permalink · · 2009-11-09 19:38:20 ·
whizkid3 Premium,MVM join:2002-02-21 Queens, NY ·Earthlink Cable Mo..	said by John Galt : I can nail up 10 plastic boxes in the time it takes you to put one metal one together. Use the right metal box and it goes in just as fast. While you're busy attaching the ground wire to the switch or receptacle - or worse yet, wiring the grounds together with a Greenie, we've moved on to the next box.
	to forum · permalink · · 2009-11-09 20:58:55 ·
nunya SEE ROCK CITY 475 MILES Premium,MVM join:2000-12-23 O Fallon, MO clubs:	reply to John Galt Try nailing that plastic box to steel studs .
	to forum · permalink · · 2009-11-09 21:03:24 ·
John Galt Forward, March Premium join:2004-09-30 Happy Camp ·CenturyLink	reply to whizkid3 said by whizkid3 : ...we've moved on to the next box. You still haven't priced it..! -- The man who speaks to you of sacrifice is speaking of slaves and masters, and intends to be the master.
	to forum · permalink · · 2009-11-09 22:31:53 ·
John Galt Forward, March Premium join:2004-09-30 Happy Camp ·CenturyLink	reply to nunya said by nunya : Try nailing that plastic box to steel studs . This is the HOME Repair and Improvement Forum. Not too many metal studs in homes...although you can get flatter walls with metal studs. -- The man who speaks to you of sacrifice is speaking of slaves and masters, and intends to be the master.
	to forum · permalink · · 2009-11-09 22:34:46 ·


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