Plastic or metal electrical boxes?

[Mace Canute]

grsthegreat, I used to work in the cellulose plant at Port Alice, BC many years ago. IIRC, the big chipper had a 2000 HP electric motor and the small chipper just a 1000 HP motor. One time both chippers took on a maximum sized log at the same time and I think the chipper blades must have been ready to be sharpened because one of the chippers stalled out. (FYI Highest paid worker in the whole place was the guy who sharpened the blades) Anyways, the electrical room that housed the panels that fed both motors was ancient and so was the equipment and when that much current draw hit it simultaneously, it couldn't interrupt it for whatever reason. Should have, but didn't. Probably blew the connectors apart and started a huge arc flash. The resulting electrical fire burnt the cr*p out of that room! It looked like you poured 100 gallons of gas in there and burned it. Very impressive!

 

[clemsonfor]

Metal boxes absolutely need to be grounded. The old wiring didn't have the ground wire so the outlets didn't have provisions for the ground prong - just hot and neutral and since there was no ground conductor in the wiring, the metal boxes at that time wouldn't have a provision to connect the ground wire to them. You absolutely can not expect a metal box to ground through the house! The house is absolutely NOT a conductor! A plastic box is non conductive. It does not need to be grounded, just the receptacle ground lug needs to be connected to the ground wire.
Electricity does not take the path of least resistance, it takes the paths of all resistances. Every path is in parallel and the amount of current that flows depends on the individual resistance of each path.
I don't think I have ever seen such dangerous statements concerning house wiring as yours are.

Sorry for ill advised comments. I dont mean to say that you dont need to ground anything, just what i thought? What i thought is wrong. But i do connect all my ground wires so thats not an issue on metal or plastic. I do notice when i replace fixtures in my house that the grounds are folded back on the lights.

 

[Code54]

Anyone use the gray surface mount boxes that Lowes and Home Depot sells? I was thinking of using them in a pole building we are putting up?

 

[2manyrocks]

I sometimes use those gray boxes.

It's hard to generalize about plastic boxes because some are flimsy and some are okay. You have to look at what you're getting.

My locally owned supply store seems to have a better deal on better boxes than the big box stores.

One comment on the spiral drywall saws--I tried cutting some outlets in drywall with one of those harbor freight multifunction tools. It's not as fast as the spiral saw, but much less dusty and I could cut a cleaner line with it. So for any rennovation work where I'm installing a box in existing drywall, I'm using the multifunction tool to make the cut.

 

[JB4310]

Metal boxes only, never use plastic, had nothing but trouble with plastic.

Except outdoors, have used the HD gray plastic, also had trouble especialy with the device screws Now outdoors I use the painted metal boxes

JB.

 

[grsthegreat]

grsthegreat, I used to work in the cellulose plant at Port Alice, BC many years ago. IIRC, the big chipper had a 2000 HP electric motor and the small chipper just a 1000 HP motor. One time both chippers took on a maximum sized log at the same time and I think the chipper blades must have been ready to be sharpened because one of the chippers stalled out. (FYI Highest paid worker in the whole place was the guy who sharpened the blades) Anyways, the electrical room that housed the panels that fed both motors was ancient and so was the equipment and when that much current draw hit it simultaneously, it couldn't interrupt it for whatever reason. Should have, but didn't. Probably blew the connectors apart and started a huge arc flash. The resulting electrical fire burnt the cr*p out of that room! It looked like you poured 100 gallons of gas in there and burned it. Very impressive!

those large electrical panels are beautiful looking, and extremely deadly.

years ago, while working on a 6000 amp panel, we had all the flash protection in place, all the blast shields, hot gloves, etc. One of the guys managed to drop a socket off of the snap-on ratchet, it shouldn't have fallen off, but did. there was a HUGE bang and flash. when we could all hear again, we went to look for damage to gear. no damage, and no socket. it completely denigrated. nothing left. nada.

it was amazing.

i hate working on live panels, but you CANT shut down a hospital.

 

[grsthegreat]

Anyone use the gray surface mount boxes that Lowes and Home Depot sells? I was thinking of using them in a pole building we are putting up?

not sure of the codes up your way, but the nat elect code requires, and most states also require, all wires from ground level up to 8 feet be enclosed in conduit (pvc pipe is ok, schedule 80) and the use of metal boxes for shops UNLESS the walls are finished. If you leave the walls exposed, you need pipe. best to check your local codes first, so you dont have an issue if you sell your place.
if the walls are finished, then wire the same as a house.

 

[clemsonfor]

hmm, that has homeowner repair written all over it.

ive found some old work where someone ran a ground to some water pipe. absolutely useless. the ground HAS to run all the way back to the point of origin to allow stray voltage to make it back to the breaker and trip it.

that is one ugly picture there. In the old days, before wire nuts. people crimped the wires together and taped them.

I thought the way that you were supposed to retrofit the old 2 wire romex to ground each outlet was to run a seperate ground wire for each outlet to a groundrod under the house. I swear i read or was told that. May be wrong to, again. By me saying this im not saying i would ever do it or that it was right, but isint the pipe the same thing? This obviously is not right as it will electrify all the drains and faucets.

 

[clemsonfor]

I sometimes use those gray boxes.

It's hard to generalize about plastic boxes because some are flimsy and some are okay. You have to look at what you're getting.

My locally owned supply store seems to have a better deal on better boxes than the big box stores.

One comment on the spiral drywall saws--I tried cutting some outlets in drywall with one of those harbor freight multifunction tools. It's not as fast as the spiral saw, but much less dusty and I could cut a cleaner line with it. So for any rennovation work where I'm installing a box in existing drywall, I'm using the multifunction tool to make the cut.

I can buy romex cheaper at the eletic supply house here in town, cheaper than lowes. I needed about 40 ft of 8/2 wire and lowes was something a little more than a $1/ft and the supply house was like $.35-.50/ft. I think its cause since CU is a commodity the supply house moves more and maybe bought that lot when the price was down and Lowes bought a container full when the price was high. That and they prolly dont move that much 8/2 wire.

 

[QRTRHRS]

Anyone use the gray surface mount boxes that Lowes and Home Depot sells? I was thinking of using them in a pole building we are putting up?

If you are talking about the Carlon brand, I have used a lot of Carlon products in my horse barns.

I prefer plastic over EMT in a horse barn because I have seen rust issues with EMT due to high moisture levels.

I always cut about a quarter inch or so off the two mounting screws on duplex outlets and switches because they bottom out and strip the plastic boxes out.

Get a product catalog from which ever box manufacturer you use. The big box stores have limited space and don't have half the options that an electrical supply outlet would. Though, I have found some exceptions. For instance, this one shop I frequented would only special order slip conduit fittings in smaller sizes if I bought a whole box. Only needing a few, I found them at Home Depot.

Re: plastic boxes in the house. Stupid first year apprentices, take the time to fasten the boxes square to the studs and set to the correct depth. PS, you can find rectangular plastic shims in varying thickness's to fix this issue so your outlets/switches are flush. You may have to adjust on the belt sander.

 

[ultrarunner]

That was permitted by the NEC at one time. That was before it was common to use plastic water lines inside and underground as replacements.

I've seen many homes from the 1940's war time construction with grounds running to the cold water pipe...

Also, when I upgrade service to a single family home from 120v 30amp main to 100amp 240v breaker the city requires bonding hot, cold and gas pipes with copper and running the same copper to the 8' ground rod with clamp rated for burial.

I personally like metal boxes... they are easy to re-thread if needed and don't crack... I also have had success with the Bakelite boxes... don't see those much anymore.

 

[grsthegreat]

I thought the way that you were supposed to retrofit the old 2 wire romex to ground each outlet was to run a seperate ground wire for each outlet to a groundrod under the house. I swear i read or was told that. May be wrong to, again. By me saying this im not saying i would ever do it or that it was right, but isint the pipe the same thing? This obviously is not right as it will electrify all the drains and faucets.

according to the N.E.C., there are only 3 ways to change a 2 wire system (without) to allow the use of 3 prong (grounded outlets). and none of them are by running a wire to ground. The code book makes you add GFCI outlets to those outlets that you want to make 3 prong. You dont run a ground wire.

As far as wires run to pipes, sewers, etc. those are BONDING wires, not equipment grounds.

 

[ultrarunner]

according to the N.E.C., there are only 3 ways to change a 2 wire system (without) to allow the use of 3 prong (grounded outlets). and none of them are by running a wire to ground. The code book makes you add GFCI outlets to those outlets that you want to make 3 prong. You dont run a ground wire.

As far as wires run to pipes, sewers, etc. those are BONDING wires, not equipment grounds.

The 1957 tract my parent's home is in had a single 16 or 18 gauge bare copper wire running under a nail at every electrical box in the house... all the homes here are built the same way... the metal boxes are "Grounded" and the copper wire attaches to copper plumbers tape fastened to the copper cold water pipe just after it enters the crawl space.

I've had a few go rounds with Home Inspectors citing items not being code and every time I would produce the applicable code at the time and point out my jurisdiction considers installations to be Grandfathered so long as the work remains undamaged or is not modified.

If everything had to meet modern code... I'm certain the majority of 1910 to 1950 homes in my city of 450,000 people would fall far short. Most of the places are still knob and tube with Edison Fuses.

Thank goodness for the Grandfather provision.

I've also had a few run ins with HUD inspectors because I have added GFCI receptacles near sinks that have no ground... the city inspector signed off as code recognized while the HUD and FHA inspectors wanted the GFCI removed and the a 2 prong ungrounded receptacle installed.

Sometimes... what's a poor homeowner to do when faced with overlapping jurisdictions?

 

[clemsonfor]

according to the N.E.C., there are only 3 ways to change a 2 wire system (without) to allow the use of 3 prong (grounded outlets). and none of them are by running a wire to ground. The code book makes you add GFCI outlets to those outlets that you want to make 3 prong. You dont run a ground wire.

As far as wires run to pipes, sewers, etc. those are BONDING wires, not equipment grounds.

Again i thought i read or was told that by someone, but you cant trust what you hear.

In my house i just ran all new wire and pulled the old cloth romex to solve the problem, along with a new sub panel.

 

[grsthegreat]

Again i thought i read or was told that by someone, but you cant trust what you hear.

In my house i just ran all new wire and pulled the old cloth romex to solve the problem, along with a new sub panel.

if a home inspector or inspector of any kind tells you that you cant use a GFCI on an ungrounded system, their idiots.

The National Electrical Code has stated that this is the only acceptable way to do it. has stated this for over the 30 years that ive been an electrician.

The National Electrical Code (NEC) 406.3(D)(3) permits any of the following installations when replacing a 2-wire ungrounded receptacle:
(a) Replace it with another 2-wire receptacle;
(b) Replace it with a GFCI-type receptacle and mark the receptacle with the words "NO Equipment Ground" ; or
(c) Replace it with a grounding-type receptacle protected by a GFCI device (circuit breaker or receptacle). Since the grounding terminals for the receptacles are not grounded, you must mark the receptacles with the words "GFCI Protected and NO Equipment Ground" By the way gfci receptacles come with these peal and stick labels.



A GFCI-protected grounding-type receptacle without an equipment-grounding conductor is safer than a grounding-type receptacle with an equipment-grounding conductor, but without GFCI protection. This is because the GFCI protection device will clear a ground-fault when the fault current is 5mA (+ or - 1mA), which is less than the current level necessary to cause serious electric shock or electrocution.
A grounding-type receptacle without a ground is a safe installation, as long as the protection circuitry within the GFCI device has not failed from shorts or voltage transients.



There is an interesting clause that states if you add one or more NEW outlet to an existing system that is ungrounded, they allow you to run a wire to a nearby cold water pipe IF that pipe is part of the grounding electrode system of the structure. but this ONLY applies to NEW outlets added to an existing system. All original outlets must be grounded to panelboard OR be GFCI protected. This is a weird clause.

 

[ultrarunner]

Thanks for the research... knowledge is power and I often find it is very useful to be able to reference applicable codes, especially on the jobsite.

 

[andrec999]

There's alot of good information here from very knowlegable people.
My thinking is when we are dealing with electriciy, it is not the place to save money , as we are dealing with our family's lives.

I have made alot of work myself when building our house, but I always had a qualified electrician , and the best in my area , to check my work at the end and do the final connection to the box.

The building code is the ''minimum'' protection code and sometime, for safety ,you have to go better than what the code requires.

 

[JDgreen227]

The 1957 tract my parent's home is in had a single 16 or 18 gauge bare copper wire running under a nail at every electrical box in the house... all the homes here are built the same way... the metal boxes are "Grounded" and the copper wire attaches to copper plumbers tape fastened to the copper cold water pipe just after it enters the crawl space.

I've had a few go rounds with Home Inspectors citing items not being code and every time I would produce the applicable code at the time and point out my jurisdiction considers installations to be Grandfathered so long as the work remains undamaged or is not modified.

If everything had to meet modern code... I'm certain the majority of 1910 to 1950 homes in my city of 450,000 people would fall far short. Most of the places are still knob and tube with Edison Fuses.

Thank goodness for the Grandfather provision.

I've also had a few run ins with HUD inspectors because I have added GFCI receptacles near sinks that have no ground... the city inspector signed off as code recognized while the HUD and FHA inspectors wanted the GFCI removed and the a 2 prong ungrounded receptacle installed.

Sometimes... what's a poor homeowner to do when faced with overlapping jurisdictions?

"KNOB AND TUBE"....those three words as applied to electrical service give me the shivers....I have to wonder if the insurance companies that are covering the homes you mention have any idea how widespread the problem is? Yes, there has been a LOT of useful information supplied by many qualified members in this thread, when I started it, I didn't anticipate the number of responses that have been made...and I have learned something from every one of them.

Thanks to all !!!

 

[ultrarunner]

"KNOB AND TUBE"....those three words as applied to electrical service give me the shivers....I have to wonder if the insurance companies that are covering the homes you mention have any idea how widespread the problem is? Yes, there has been a LOT of useful information supplied by many qualified members in this thread, when I started it, I didn't anticipate the number of responses that have been made...and I have learned something from every one of them.

Thanks to all !!!

At least a third of the housing stock in Oakland CA is pre WWII... there was a huge building boom here from 1910 to about 1930... Nice Craftsman Bungalows.

A lot still have Edison Fused "Mains" with knife switch disconnects. Just about all have Knob and Tube...

I've upgraded quite a few over the years and the standard practice here is to leave the knob and tube light circuit and new wire everything else... Originally, these homes had a 30 amp main with a 15 amp light circuit and a 20 amp plug circuit for 3 bedroom 1200 square foot homes... of course they all have natural gas for cooking, heating and hot water.

Most of the electrical fires per the fire department are improper space heating, extension cords and over-fused circuits... knob and tube really has not been a factor.

 

[bdeboer]

I have had good luck with the thicker Carlon SuperBlue boxes like this, they do not deform like the cheaper blue boxes:

Carlon Sales | Carlon SuperBlue™ Hard Shell Boxes

Also Arlington makes box extenders that slip into the box for setting the depth if the drywall is shimmed out or a tile backsplash is added on top of the drywall.

Amazon.com: Arlington BE1-2 Electrical Outlet Box Extender 1-Gang 2-Pack: Home Improvement