Old two prong outlets, can I "update" these?

[Dick in Wisconsin]

The house was built in 1955. There were a few updates to the electrical over the years, but very few. Most of the outlets in the house are like this pictured with no center ground prong hole. I believe the wiring has a metal sheath and might be called "BX"?

Today's wiring has three wires: hot, neutral, and ground.

Is it correct to presume that the 1955 wiring has a hot, neutral, and the metal sheath is the ground?

Can I replace the existing old two prong outlets with current outlets (three prong) by attaching the ground screw of the new outlet to metal box in the wall? I'm presuming the metal box in the wall is attached to the metal sheath of the cable which is grounded back at the panel.

If not, what is the procedure for updating these outlets without pulling new wire back to the main panel.

 

[TonkaJoe]

You most definitely can update these to the ''new style'' outlets through the use of a GFCI.
Even if an outlet box isn't grounded, installing a GFCI in it will still protect you (and your tools and appliances) from ground faults. BUT an ungrounded GFCI can't safeguard sensitive electronics, such as a computer or phone, from the interference caused by stray currents. IF there is no ground wire to hook up The National Electrical Code requires you to stick a label on the receptacle that reads, "No equipment ground." These labels come in the box with a new GFCI.

 

[brook41]

You are correct the outside metal jacket of the bx is the ground. Ground tails can be purchased at Home Depot . If you are lucky there will be an existing 10/32 tapped or untapped hole in the box, if not you will have to drill and tap one. A 5/16 nut driver makes it easier to install the ground tail to the box. I would also make sure the existing box is grounded.

 

[Dick in Wisconsin]

You most definitely can update these to the ''new style'' outlets through the use of a GFCI.
Even if an outlet box isn't grounded, installing a GFCI in it will still protect you (and your tools and appliances) from ground faults. BUT an ungrounded GFCI can't safeguard sensitive electronics, such as a computer or phone, from the interference caused by stray currents. IF there is no ground wire to hook up The National Electrical Code requires you to stick a label on the receptacle that reads, "No equipment ground." These labels come in the box with a new GFCI.

So originally, this type of wiring had no grounding?

I remember adapters for plugs with a ground prong that had a wire or clip that could be attached to the metal screw in the middle of the plate. I always presume that was the grounding protection then through the metal box to the metal sheathed cable and back to the mail panel. Is my presumption correct? or am I off base? Thanks!

I think Brook41 answered my question. Thanks!

 

[TonkaJoe]

You are correct the outside metal jacket of the bx is the ground. Ground tails can be purchased at Home Depot . If you are lucky there will be an existing 10/32 tapped or untapped hole in the box, if not you will have to drill and tap one. A 5/16 nut driver makes it easier to install the ground tail to the box. I would also make sure the existing box is grounded.

^ Yep this is what you need right here

 

[Stuff]

With older BX cable (generically called AC or armor clad) the outside jacket should not be used as ground. Instead of tripping the breaker it can heat up and start a fire. Newer cables have an extra bonding strip to make it usable as a ground.

Also - If you have the newer cable installed properly to metal boxes you can use spec grade receptacles and skip the tails.

 

[theoldwizard1]

BUT an ungrounded GFCI can't safeguard sensitive electronics, such as a computer or phone, from the interference caused by stray currents.

Not exact correct. GFCI measure the current going in and the current going out. If they are not equal, the GFCI trips. "Stray" current in or out will likely cause this type of inequality.

Some equipment will "sense" if there is a ground and will not start up (modern computer controlled furnaces).

 

[n8n]

'55 should be grounded. But verify and make sure.

Sent from my XT897 using Tapatalk

 

[theoldwizard1]

Is it correct to presume that the 1955 wiring has a hot, neutral, and the metal sheath is the ground?

Most wiring from the early to mid 50s is just 2 wire/ no ground Romex, so there is no "metal sheath". If you do try wiring in a 3 prong out
let with a pigtail to the metal box, you should check it with a simple outlet fault detector.

There could be another problem. My daughter's old house was built in '48 and definitely had 2 wire no ground wiring. When we remodel the kitchen we installed proper 14/2 with ground. One wall we opened was shared with bathroom. The metal boxes in the bathroom were grounded to the cold water pipe. The old cold water pipe that was cut off and left dangling inside the wall when copper was install !

 

[dw1]

Well... I looked to see what version of the NEC the state of Wisconsin is on (Still not sure) Ky has adopted the 2015 NEC, but if you are changing those outlets, depending on code version, they might have to be tamper proof and arc fault protected And, depending where it is inside your house, GFI protected, but all the above should work fine, just wether or not code compliant!!

 

[alfredeneuman]

With older BX cable (generically called AC or armor clad) the outside jacket should not be used as ground. Instead of tripping the breaker it can heat up and start a fire. Newer cables have an extra bonding strip to make it usable as a ground.

Truer words have never been spoken.

The armor can turn into one spiral heating element.

It was de-listed and not re-introduced until years later as AC cable with a bonding strip.

 

[mikegt4]

My parent's 1956 house (that they bought new and I grew up in) has those same receptacles. All the metal boxes are grounded with a bare copper wire that is daisy chained along roughly the same route as the Romex (silver woven fabric covered). Over the years some of the receptacles have been changed over to 3 prong by adding a ground pigtail attached to the box as Brook41 described.

 

[Mustang51js]

If the boxes are grounded just get some self grounding receptacles

 

[alfredeneuman]

A simple 3 light outlet tester won't test the integrity of the ground, because there simply isn't enough load through the LED on the tester.
You could pick up the ground from a piece of grounded metal lath wire in contact with the box and have the outlet tester light up and shown as good.
To test the quality of the ground requires that a load be imposed on the ground by using an instrument such as an Ideal Sure-Test.


If you have any doubts at all if it's grounded put a GFCI outlet into the first receptacle in the circuit, and run the rest off the load side of the GFCI.

That would apply to the BX that's being discussed as well.