electrical box ... fiberglass or plastic?

[bww_mnm]

Hi.

I haven't done electrical in a while. I was at HD and saw grey fiberglass box and the blue plastic boxes. What are the pro and cons? Also, how do you "attach" the wire to the fiberglass box? Blue, it kind of crimps in when you slide it in. Doesn't look like that happens w/ grey.

Thanks, Brad

 

[MrMark]

Gray? Is it a PVC box for use with PVC conduit? There are also gray plastic "smart boxes" but HD does not carry those.

 

[LIVELY]

the fiberglass box holds it's shape better then a plastic box.
we use both styles here
i prefer the blue plastic most of the time

the wire is usually stapled out from the box to a stud

 

[Busted_Knuckles]

I like the fiberglass, for they dont "move", or are far more rigid than the plastic. Its a personal preference, grab one of each and install, and you can see for yourself which one you like working with better. Ive used the blue plastics in the past. I just used an adjustable one last week, because they dont sell adjustable boxes in fiberglass near me.

 

[MrMark]

the heavy duty carlon sold by home depot (they may be fiberglass reinforced or smc) are blue, not gray.

All boxes with the exception of single gang plastic require wire retention means at the box. And, the single gang plastic have to be stapled closer than the other boxes, within 8 inches vs. 12 inches, IIRC. The plastic boxes (other than the single gang) have spring fingers or some type of internal clamp. They ****.

 

[REAL HOT SCHITT]

Fibre glass is glass fibre spray with a resin binder.... Good if its not exposed to sunlite (u.v) and heat as it degrades and turn to a dusty mess
plastics o.k for internals, but galvoed steel is still best.

 

[bww_mnm]

Thanks for the feedback. It's very helpful.

If I read correctly, it's personal pref. blue box standard cheapo plastic has "retainer clip" built in, but still staple within 8". The gray (lowes were blue, but hd were definitely grey) don't have the clip, so simply staple to stud within 8" and it's code?

Thanks Again. Brad

 

[MrMark]

No.

The general rule is that you must staple any wire within 12 inches of where it enters a box and the other general rule is that each box must have a clamp at the box to secure the wire. You also need at least 6 inches of wire extending through the box; I use 10.

There is an exception for single gang plastic only. Single gang plastic have a knock out tab in the back and the wire is not secured. For this exception, the wire must be stapled within 8 inches of the box.

I've never seen a fibreglass box anywhere. The super blue carlon are not fibreglass; I just looked it up.

 

[Busted_Knuckles]

No.


I've never seen a fibreglass box anywhere. The super blue carlon are not fibreglass; I just looked it up.

My house is full of them, dont know the name brand, bought them at Menard's, they are light brown in color, and when "smashed" with a hammer, they certainly appear to be fiberglass...?

Im not at that house right now, or Id shoot a pic...

 

[MrMark]

My house is full of them, dont know the name brand, bought them at Menard's, they are light brown in color, and when "smashed" with a hammer, they certainly appear to be fiberglass...?

Im not at that house right now, or Id shoot a pic...

We don't have Menards here. I just searched for a fiberglass box and there is a company called allied that makes them. I've just never seen or heard of them until today. HD doesn't sell them to my knowledge.

 

[MrMark]

http://www.alliedmoulded.com/index....egory/template/products_sub_res/categoryid/54

Is this what Menards sells?

 

[Busted_Knuckles]

We don't have Menards here. I just searched for a fiberglass box and there is a company called allied that makes them. I've just never seen or heard of them until today. HD doesn't sell them to my knowledge.

Yes, I went to their site, Id say from the images that Im about 99.9% sure those are the brand Ive been buying.

 

[bww_mnm]

Here's a pic of a 2 gang that our builder put in. Here in MN, both Menards and HD carry them. Lowes have the above mentioned heavy duty blue Carlons. No clamp at the box which is why I was confused. I'd think/believe the builder was to code?

 

[bww_mnm]

also, lighting use same fiberglass boxes and doesn't appear to have internal clamps either.

 

[Busted_Knuckles]

Not sure what clamp your looking for, but that black flap, prohibits the romex from being pulled back out of the box.

 

[MrMark]

The company is in Ohio, and it appears to have a presence in MN. Maybe a regional stronghold for this type of box.

Says they're are best suited for chicken coops, cattle barns, hog pens and outhouses. Does this make sense?

 

[bww_mnm]

just confirmed it's allied out of ohio.

 

[bww_mnm]

The company is in Ohio, and it appears to have a presence in MN. Maybe a regional stronghold for this type of box.

Says they're are best suited for chicken coops, cattle barns, hog pens and outhouses. Does this make sense?

Does it really say that? I will say w/ a 4.5 yr old and 4 mo old, it's a little farm-like here.

They are suppose to be more resistant to weather changes.

 

[MrMark]

I would question whether they are listed for two romex cables through a single hole like that (I doubt it) but there are internal clamps there. I've never seen that style before. It looks like you just slide it.

 

[bww_mnm]

I'm still struggling with the lack of "clip" on it for retainment. my builder didn't seem to do anything.

Again, i really appreciate the guidance.

- Brad

 

[Busted_Knuckles]

I would question whether they are listed for two romex cables through a single hole like that (I doubt it) but there are internal clamps there. I've never seen that style before. It looks like you just slide it.

Yes, the romex just slides in, and is reluctant to pull back out, you side a screw driver under the flap, and lift up to release its "grip". The black flap is "spring loaded" and has a "sharp" tip that digs into the jacket of the romex. Two in one hole would side step the holding ability of the flap.

 

[bww_mnm]

I'm just going to go w/ the blue cheapos that I'm use to.

 

[MrMark]

Does it really say that? I will say w/ a 4.5 yr old and 4 mo old, it's a little farm-like here.

They are suppose to be more resistant to weather changes.

Yeah, it really says that.

I wonder where I can get them locally? The plastic are not strong enough for me when they get past two gang.

 

[MrMark]

Yes, the romex just slides in, and is reluctant to pull back out, you side a screw driver under the flap, and lift up to release its "grip". The black flap is "spring loaded" and has a "sharp" tip that digs into the jacket of the romex. Two in one hole would side step the holding ability of the flap.

But are they listed for two cables like that? I think not. Only one cable would be captured by that black retainer. The other cable would be free to pull right out. I think that is a code violation right there.

 

[bww_mnm]

Yes, the romex just slides in, and is reluctant to pull back out, you side a screw driver under the flap, and lift up to release its "grip".

I saw the black flap in the 2 gang. The single gangs that the builder left over don't have the flaps though.

This has been a helpful discussion and has convinced me to go w/ the blue boxes I know.

One last thought: Fiberglass might be easier to cut drywall around w/ rotozip/

 

[bww_mnm]

Not sure what clamp your looking for, but that black flap, prohibits the romex from being pulled back out of the box.

busted knuckles, i just saw your comment on black flap. thanks.

 

[Busted_Knuckles]

But are they listed for two cables like that? I think not. Only one cable would be captured by that black retainer. The other cable would be free to pull right out. I think that is a code violation right there.

I have no idea, Im a mechanic, not a sparky, but I did stay at a Holiday Inn Express last night. Seriously though, no, 2 romex in one hole, and I dont see it clamping. It can only "dig" into one cable at a time, 2 stacked in the same hole, nada...

 

[MrMark]

I'm still struggling with the lack of "clip" on it for retainment. my builder didn't seem to do anything.

Again, i really appreciate the guidance.

- Brad

I can't tell from your pic. Is the black clip thing missing on the inside of your box at the top where those cables come in (4 cables)

 

[MrMark]

I saw the black flap in the 2 gang. The single gangs that the builder left over don't have the flaps though.

This has been a helpful discussion and has convinced me to go w/ the blue boxes I know.

One last thought: Fiberglass might be easier to cut drywall around w/ rotozip/

Yeah, it might, but you should be using guide point bits anyway.

Remember the single gang plastic boxes are an exception - they have no clamping means, just a KO hole.

 

[Busted_Knuckles]

Yeah, it might, but you should be using guide point bits anyway.

Remember the single gang plastic boxes are an exception - they have no clamping means, just a KO hole.

Yes, all my single gang do not have a "flap" not sure why, but I did ponder that. Yes, they do rotozip nicer than the flimsy blue ones, Ive not tried the upgraded carlon boxes though...(with the rotozip).

 

[bww_mnm]

"Yeah, it might, but you should be using guide point bits anyway."

I'm clearly not the expert on this thread ... what's a guide point bit?

I just read allied's website. Looks like you can just push romex through w/o having to knock out a tab:

Pulling Non-Metallic Sheathed Cable
Wires can be simply installed in Allied's fiberglass boxes by inserting the end of the wire through the thin fiberglass layer at the top of the knockout. "With PVC boxes you must use a tool to pop the molded-in plastic tabs which hold the knockout in place. This amount of labor is small when considering one box, but when you wire an entire house of boxes it certainly adds up", states Zolman.

 

[MrMark]

"Yeah, it might, but you should be using guide point bits anyway."

I'm clearly not the expert on this thread ... what's a guide point bit?

I just read allied's website. Looks like you can just push romex through w/o having to knock out a tab:

Pulling Non-Metallic Sheathed Cable
Wires can be simply installed in Allied's fiberglass boxes by inserting the end of the wire through the thin fiberglass layer at the top of the knockout. "With PVC boxes you must use a tool to pop the molded-in plastic tabs which hold the knockout in place. This amount of labor is small when considering one box, but when you wire an entire house of boxes it certainly adds up", states Zolman.

Got it, that explains the picture I posted earlier. Yes, on the normal Carlon plastic you need to KO the little tab with a screwdriver or needlenose.

Guidepoint bit is used for tracing around a fence. You go counterclockwise witht the rotozip on these. Guidepoint bit is smooth on the end so as to not cut the box up. Set your depth exactly right and it will work for you.

 

[bww_mnm]

I just verify w/a single gang box that builder left, just push the wire through the KO, no tool needed. And like Mark and Knuckles are stating, 2 gang has a built in tab for wire retainment.

The picture is becoming clearer. Maybe I will use these. I do like how rigid they are.

Many thanks for the help.

 

[bww_mnm]

A little more info after surfing Allied's site:

Speed "K" Klamps™

http://www.alliedmoulded.com/index....egory/template/products_sub_res/categoryid/73

Allied offers a nonmetallic wire clamping system that automatically locks your wire in place for a secure hold. No screws to loosen and tighten makes wiring faster and easier saving time on installation. The Speed "K" Klamp™ allows the wire to be inserted through the knockout and the memory retaining feature of the clamp prevents wire from being pulled back from the box.



Should a knockout be inadvertently opened and not used, the Speed "K" Klamp™ is considered sufficent closure of the opening per UL. Click here for UL documentation.

 

[Busted_Knuckles]

Your welcome, good luck !

 

[MrMark]

I'd definitely use them. Good luck!

Now I'm not sure on the counterclockwise advice. I'm trying to remember how I cut out window openings with the flush trim bit as this would be the opposite for an electrical box.

I think counterclockwise is right. With any router type device the way I like to think of it is to consider the effect of the clockwise bit rotation with you pushing against or following the guide. You want the biting bit to not be pushing the router opposite your direction of force against the fence or guide. Make sense?

 

[bww_mnm]

Thanks again! I'll definitely post pics / my experiences.

- Brad

 

[Busted_Knuckles]

I'd definitely use them. Good luck!

Now I'm not sure on the counterclockwise advice. I'm trying to remember how I cut out window openings with the flush trim bit as this would be the opposite for an electrical box.

I think counterclockwise is right. With any router type device the way I like to think of it is to consider the effect of the clockwise bit rotation with you pushing against or following the guide. You want the biting bit to not be pushing the router opposite your direction of force against the fence or guide. Make sense?

I run counter clockwise, Im running an old school roto-zip (10+years old), I think the first model they sold. If you run clockwise, the gryo effect will wander you off the box and into no-mans land.

 

[Norcal]

The only issue I have w/ Allied fiberglass boxes is they are prone to shearing device mounting screws, other then that I like them & would rather use them over Carlon products.

 

[electrican]

http://www.alliedmoulded.com/index....egory/template/products_sub_res/categoryid/54

Is this what Menards sells?

they brake easy!