How to Ground a Two-Prong Electrical Outlet | Ask This Old House

[Music] the problem is in here on the unfinished side we were going through the whole house with the home inspector and um he told us that this outlet was ungrounded okay i've been kind of afraid to use it because honestly i don't know what that means sure so we can look at it right away and tell that it is an ungrounded receptacle and you're only two prongs we have the hot and the neutral we don't have any terminals for the ground wire so i can kind of explain how all this works and hopefully make it make sense a little bit more to you when you call for power on a device current is sent from the breaker in the electrical panel through the black wire often referred to as the hot the current will travel through the wire and into the appliance giving it power the used electrical current will then return back to the panel through the white or the neutral wire thereby completing the circuit for ease these two wires are usually encased together in a jacket when everything in the house is operating properly there should be no issue with the flow of electricity technically houses are powered with alternating current so the current alternates back and forth as it distributes power but for the sake of keeping the explanation simple this is a general flow of electricity now if a fault occurs somewhere in the device or the receptacle that electric current will travel where it's the easiest if the device being powered is made out of metal like many appliances the whole thing has the chance of becoming electrified and can shock someone that touches it to control fault current code added the requirement of a grounding wire which is usually just a bare copper wire that goes inside of the jacket with the hot and neutral wires the bare copper is extremely conductive so if there's ever a fault the current will travel through the grounding wire back to the panel and the surge of current will trip the breaker cutting power from that device all right colin so we have a couple of solutions for this problem okay so the easiest thing that we can do is we can leave the existing wiring as it is and install a ground fault circuit interrupting receptacle how this works is it senses a certain amount of power coming in and a certain amount of power going back out it wants to see the same amount so let's say we have 10 amps coming in it wants to see 10 amps coming back on the other side if it sees 9.995 amps something as small as 5 000 of an amp this is designed to trip and give you an added layer of protection it sees that power going somewhere else that it shouldn't and that's why it trips that's why we use them in something like a kitchen outdoors we don't know if the power is going to water somewhere that it shouldn't be going so we want to have this in place the good thing is we have to have this in an unfinished basement if we're installing a receptacle anyway so we have to put this here the downside is we still don't have the equipment grounding conductor that i really want to have in this system so what i prefer to do is since we have access to everything it's a wide open basement and a short run i'd really rather run a new cable with the equipment grounding conductor in it so everything is sized properly everything is safe clean and new sounds great all right colin now we're going to turn that circuit off take the multimeter plug that into the receptacle and let me know we don't have power all set all set that's it heath all right perfect now that's off we can take that apart not only is that receptacle and grounded but over here behind the washing machine this receptacle has a bunch of violations as well i think the best thing to do is take both of these out install a single new dedicated laundry circuit to make everything correct all right one down that's that so now we can mount the metal electrical box to the concrete wall we've chosen an electrical metal box because we don't need additional lumber to mount this to the concrete so this conduit coming down the wall is going to house the wire coming down to our electrical box we have to put a slight bend in this conduit in order to fit in the box since this is a standard connection size they actually make a conduit bending tool that'll let us bend this conduit to the exact size that we need since this receptacle is going to be used for a laundry circuit we want to make sure we run a 12 gauge wire because it is code and it can handle a heavier load we want to make sure that we turn the power off at the main breaker that way when we take the panel cover off there are no energized parts inside we're going to use an arc fault breaker with a hot and neutral tied to the breaker the white pigtail will tie to the neutral bar and the ground we've just installed will tie to the grounding bar all right we're just going to plug this last machine in that's all powered on you're all set that looks awesome thank you so much for the explanation thanks for having me it's functional much safer install should be happy perfect do you have time for cold drink yeah let's go take a look at that bar you built all right i think you've earned it always five o'clock somewhere right hopefully so if you have an outlet a receptacle that looks like this with two prongs you know that is ungrounded no ground if you see one with three prongs is it grounded not always the case and that's why you want to grab a little tester like this for six or seven dollars at your home center you can pick one of these up and it can kind of tell you the situation you have going on inside that receptacle three prongs on one side three lights on the other side a little grid up there and so if i plug it in i get one light in the middle uh that says open ground what does that mean it means it's the exact same situation as this even though they put a three-prong receptacle in there's still no ground no ground wire no ground wire they just did it to adapt to their device tricky okay and if i put this one in here two lights that tells me hot neutral reversed right so that actually on the wrong terminals they've swapped the black and the white wire are on opposite sides but it's working so what do i care about that you care about that because if you have an appliance or a device plugged in the on off switch isn't really turning it on and off anymore it's stopping the circuit from being complete but power is still flowing through the system instead of stopping at the switch don't put your knife in the toaster do not put your knife in the toaster okay and then the final one two lights over here yeah all good that's what it should look like oh all right you just earned yourself another cold one all right thanks thanks thanks for watching this whole house has got a video for just about every home improvement project so be sure to check out the others and if you like what you see click on the subscribe button to make sure that you get our newest videos right in your feed

Channel: This Old House

Views: 1,008,179

Keywords: This Old House, Ask This Old House, DIY, Home Improvement, DIY Ideas, Renovation, Renovation Ideas, How To Fix, How To Install, How To Build, Heath Eastman, electrical, 7-10 minutes, Ask This Old house clips, Ask This Old house series, Ask This Old house episode, Ungrounded Two-Prong Electrical Outlets, Two-Prong Electrical Outlets, Electrical Outlets, How to Replace, Outlets, Ask This Old House master electrician, master electrician Heath Eastman, electrician Heath Eastman

Id: 1TZ47h_UUSc

Length: 6min 56sec (416 seconds)

Published: Sun Apr 12 2020

Reddit Comments

[u/polank34]

What about it? It's not prohibited, and even required in some cases.

NEC 334.15(b). (B) Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, or other approved means.

[u/glazor]

334.15(B).

[u/BurnCannabiz]

We have had engineers tell us to pull teck in pvc.

[u/SamuelSmash]

Nm inside conduit is even allowed in places where NM is not allowed alone. Such as types 1 and 2 construction.

[u/trm_90]

I’m not a fan of it, but it is permitted. NM cable isn’t allowed in exposed locations, but is allowed in conduit when subject to physical damage, so this is allowed. I would treat NM cable in conduit the same as MC though, so I would use a NM to EMT coupling and strip the NM cable after the connector so the sheath is removed and only individual cables are in the raceway. I don’t know for sure if just shoving NM cable down a conduit without some sort of connector is allowed, but I wouldn’t do it. Using the EMT as a sleeve without a connector would make it possible to pull the NM cable down and potentially damage it where it enters the conduit.

[u/Mzam110]

Nevermind I am just not used to this cause I live in Chicago where there is no romex