To the electrical experts at Breaktime,
I have a question regarding installing a short length of conduit in my kitchen.
My frig is located in an alcove slightly bumped out from the kitchen (old house). The receptacle and box are located in the back corner of this alcove. Currently, about 3 feet wire from the floor to the receptacle is only stapled and exposed with no protection. Judging by the wire’s thick paint job, I would guess its been this way for quite a while.
What’s the best way to protect the wire? I was thinking of using flex metal conduit since it’s such a short length, but I’m definitely open to suggestions. If I did use metal conduit, could it just butt up aganist the floor (provided it was secured of course) or would it need to be slightly below the floor?
I would also appreicate any recommendations on how to secure the conduit to the box. I think the cable clamp that’s currently installed is too small for conduit large enough for 12/2 wire. Bigger box with bigger knockout or something else?
Thanks for taking the time to read this. I’m sure I’ve made it sound much more complicated than it really is, but I want to make sure it’s done right.
Thanks for any info!
Patrick
Replies
Romex is OK to be exposed if it follows the surface of building structure and is not subject to physical damage.
Now what is subject to phyiscal damage is up to the inspector. But I would think that hidden behind the frigerator it would be well protected.
I agree.It could be sleeved in some flex if it made him feel better or the inspector objected to the exposed, but relatively well protected by the refrigerator, NM. Provision would have to be made to ground the armor or other conductive materials. An alternative I have seen is to run a 1by2 flat beside the NM. The inspectors reasoning being that conceivably the fridge could impact the cable when it is being tilted into place. Slightly more likely that the sun going nova but a 3' run of cheap 1by2 and a couple of toggle bolts is cheap and easy.I would leave it as is and let the inspector, if any, make the call. If he objects you have a pocket full of options.
Thanks for your help guys. I won't be using any conduit for the wire (saves a lot of work too). Anyway, I wonder if somebody might explain (but, I don't want to do any work out of my league) how one would go about grounding conduit?
I'm refering specifically to the metal flex stuff. I have some in my garage and I would like to know if it's correctly grounded.
Thanks again, everybody here is a big help.
Patrick
Flex connected to a grounded metal box, without concentric KOs, will ground the flex. In the case of concentric KOs a grounding bushing would be employed and a ground wire run to it. That way if the concentric KOs give up, not an uncommon situation, the ground is maintained.
By concentric KOs, you are talking about those prepunched holes in boxes? The smallest is 1/2". Usually the next and last is 3/4". But on a panel or a big box there will be others.
So let's say you have a 1/2" and a 3/4". In the process of KOing the half you weaken the 3/4". Time now takes it's toll and the 3/4" fails and one is just left with the ground at the other end of the flex. Is this the situation you are refering to?
I have a limited sample of installations to make my judgement on. But it looks to me like sparkies cheat like crazy and often fail to properly connect the EGC: true or false?
If I drive a dw screw into the stud with a little washer and run a bare or a green under the washer to the pig tail with the rest of the EGCs is the box properly grounded? Or is this the case of the sheet metel screw that's not allowed?
Big Macs - 99 cents
Concentric KOs are where there is a 1/2" KO within a 3/4" KO within a 1"KO...Slightly different are the eccentric KOs. In these the various KOs share a side and the metal to be removed more closely resembles a 1/4 'moon' shape. Adding grounding bushings, locknuts or other means when concentric KOs are used is required for voltages over 250v to ground and at the service last I checked. Of course the code is concerned with ground path as it is built and only secondarily as it will wear down to.Most electricians have seen situations where the connector on a length of conduit is no longer connected to the box because the concentric KOs have failed. The connector is often firmly connected to the ring of steel that is the KO for the next larger size but the ring no longer contacts the box.This is much more common with EMT or rigid conduit. With PVC it doesn't matter as much as the plastic doesn't need grounding, technically bonding. With flexible raceways like BX or flex it is a lot less common as the flexibility of the raceway removes the leverage and movement that causes the KOs to fail.Some claim eccentric KOs eliminate this issue by having one edge of the hole a fixed part of the enclosure. Sounds good and this style KO is a bit firmer and more resistant to damage. But I have seen where the crescent shaped KO pieces are forced into the box and this allows the connector to slide off the fixed edge of the hole. The result it a conduit without a connection.It is a judgment call as to how far you go to make sure the installation will continue to be sound in difficult situations. In high abuse areas I tend to look closely at flexible raceways. If I use EMT or RMC I try to take steps to assure longevity. Sometimes it makes sense to eliminate the KOs altogether. Unpunched boxes are available in the larger sizes. Simple enough, but time consuming, to drill and make my own KOs. You can also reinforce concentric KOs in a prepunched box by installing reducing rings. The wider range, like 1" or 2" to 1/2" are great for this. Increasing the strapping of the conduit, to eliminate any movement, helps. Of course adding a grounding bushing at any location guarantees that if the KO fails the ground path will be maintained. It is a judgment call as to how likely a KO is to being damaged and exactly how much of a hazard this is. If the conduit is firmly bonded at both ends, if the conduit is unlikely to be used as a pull-up bar, if a ground conductor was pulled instead of the conduit being used as the ground path, If I am at a dead run. All these things would make me less worried and less likely to spend a lot of time on it.Possibly more interestingly, if carpenters can rhapsodize for hours on a hammer sparkies can go long on bonding, the question of the grounding screw: No. The screw is wrong, has to be a fine thread screw as they have more contact area. Also the screw is both supporting the box and maintaining the ground connection. The ground screw has to have only one job, grounding.On the other hand if there was no existing ground and your drywall screw was the best you could manage, in reasonable time and money, it would be a big improvement. In a lot of areas any ground relatively well done it considered 'good', if not just good enough.
I tried these box ground clips, but I sure did not like them. They seemed hard to get on. Do the competitors make something better?
http://www.usahardware.com/inet/shop/item/30070/icn/20-716951/gardner_bender/ggc_1508.htm
I'll think more about running a dedicated EGC when I need a higher reliability ground. No that you mention it I have seem the conduit torn loose and the ground lost.
Big Macs - 99 cents
Those clips can be a PITA. Even the good ones need to be tight. I have had luck using a pait of pliers to drive them on. Loosely grip around the ground wire and use your other hand to smack the bottom of the handles. Some seem to go on better with a wide blade screwdriver held in place and driven with the Kleins. Some brands don't go on though some of this has to do with their being different models for #12 and #14 wire. Use a #14 model on #12 wire and it is hard to get on. Using a #12 model on #14 wire leaves the wire loose and useless as a ground. Some brands, particularly the cheaper ones, are made out of such soft steel that they don't grip anything even if you use the right size.Most boxes have a prethreaded 10-32 hole that will take a standard hex-head ground screw. Arrange a loop of wire and drive in a screw. A nutdriver or screw holding screwdriver helps get into the back of the box. If the ground screw has a shoulder the nutdriver is easier. If not use duct seal to partially fill the socket of the nutdriver. Being slightly sticky it also helps grip the screw. I get by using a finger to hold the screw and a lain Phillips screwdriver but I do it a lot. A small flashlight will help you see the hole.The screw is dead simple and very effective. Sometimes the simple ways are best.
Most boxes have a prethreaded 10-32 hole that will take a standard hex-head ground screw.
You learn sumthin new everyday. I'll try it.
Big Macs - 99 cents
If you are going to go with some form of conduit, I would think WireMold would look a bit better. It's square and more flat. And there are shallow boxes to go with it.ps I think the issue of "exposed" wire varies by jurisdiction. Here in Columbus, exposed wire below 8' in height has to be sleeved in something. At least in basements and garages.
You could plow a groove on the back side of a piece of molding or other pice of wood, and nail or glue it in place over the romex. Just be sure the nails are well away from the groove where the wiring is!