Electric Outlets in house: DIY or hire someone?

Some call it an adapter.

You should place that under the cover plate screw. Assuming a metal box and bx cable, that will complete the ground. Just remove the screw, stick the adapter in, and put the screw back on.

I am not an electrician but I will pass on what I have learned through home ownership over the years.

Generally whether knob and tube was used in older Maplewood homes depends on both the age of the home and quality of materials used by the builder at the time the home was built . There was a period of more than twenty years when both knob and tube wiring and ac cable wiring was used (roughly 1906-1930). Knob and tube was the less expensive option. Both exist in homes in this area.

Retrofitting knob and tube wiring requires GFCI outlet installation to accommodate three prong outlet without a grounding wire. Otherwise it not to code, and as previously stated, you basically have an outlet that looks like 3 prong but doesn't have any of that functionality, it also shouldn't pass home inspection. Overall, when possible replace knob and tube.

Here is the hitch on the ac cable (metal clad 2 wire cable from that era) that many of us have in our homes from this era, many times people will try to ground new 3 prong outlets by connecting them to the armor sheath or via a grounding wire to the metal receptacle box. However, this was not the intent of the flexible sheath to act as a ground back in the early years, and it wasn't designed to carry a load. It can overheat under load and start a fire. When you plug in a tester, it may show a grounded circuit, it even met code for some period of time to retrofit this way.

New armored cable (bx) will note on it if there is a bonded ground in the armor, which is now required to use the armor in this way.

Sad truth for many of us may be that we don't know what our current risks are unless we have a licensed contractor who knows what they are doing pull the plates on the outlets and see what is in there. End point: when doing renovation especially when the walls are out, take the opportunity to upgrade wiring to current codes.

Bx was perfectly fine for grounding outlets, it was used for that purpose. The bx is grounded to the outlet and junction boxes making a continuous loop back to the panel. Is todays stuff safer, yes. But it was perfectly fine to use as a ground. When it was installed grounded outlets were not required, so maybe thats were the confusion is? As long as all the other wiring is in place it will work fine. If your remodeling or someone put in a plastic junction box along the way, thats a different story.

Thanks @filmcarp. There are maybe two or three outlets in the house that have two prongs... House was upgraded to 200 amp about 10 or so years ago, but for some reason not all outlets seem to be updated....(maybe not part of the same thing?) Will talk to my electrician about that next time he's here...

And, ditto all above about getting a good electrician's number handy

rowegr. Not trying to be snotty, but GFIC has no thing to do with what you are talking about.

Knob and Tube must be replaced with code today which provides an Earth ground. If it was converted to BX, then I bet the Earth ground is OK. A simple $5 tester from HD will tell you what you have and if you have a good Earth ground.

GFIC is a far more complex product used where water is at possible play like a kitchen, a bath room or outside.

GFIC counts the electrons leaving the hot side against the neutral and the ground. If all that go out do not come back then likely they are going thru YOU, so it trips in micro seconds to save a live.

I can be more specific but, that is a layman's explain of the GFIC.

Later,

Da, George

Also if you hooked up a gfci w/o ground it will not function

What about a gfci breaker on knob and tube wiring? Or the new arc fault breakers? Wouldn't both of those potentially improve a dangerous wiring configuration?

I would still recommend removing all knob and tube whenever possible.

Ace11- you are incorrect. not all bx is perfectly fine to use to ground a circuit, the early versions of bx (called ac) which are typically found in homes built in the era that many Maplewood homes were built do not have a bonded wire to carry the ground. NEC now requires that flexible armored cable have a bonded ground. If it doesn't, you risk the armor heating up like an oven element under a load.

jgberkley- while I understand that the GFCI primary purpose is not to replace two prong outlets, it is applicable here per code, NEC article 210-7d3 Sub-section (c) "A nongrounding-type receptacle(s) shall be permitted to be REPLACED with a grounding-type receptacle(s) where supplied through a ground fault circuit interupter".

In this application, you are not creating a ground, but you are making the circuit safer than a non-grounded regular three prong outlet.

I found this book very helpful for understanding old house wiring.

The author is very careful to recommend calling in a professional as soon as things become non-trivial.

I believe grounding with the metal jacket in BX is a retrofit for a system that was never designed with grounding in mind. The trouble is that the metal jacket has more resistance than a copper wire, but it's still better than nothing. Consider replacing with NM, or MC which has the metal jacket and a copper ground wire. There are electricians who have experience with doing this without opening up walls. I've been happy with Craig Bradley.

Sorry rowerg, I'm not wrong. Like I stated you might be confusing new codes for new building construction with retrofitting old work.

A copy and paste format this old house,

Old-fashioned two-prong receptacles connected to two-wire cables don't have the ground wires that protect people and electrical devices in case of a fault. Yet it is possible to retrofit a new three-prong or GFCI receptacle into the same outlet box without any rewiring, as long as the box itself is grounded.

Luckily, metal boxes attached to armored, or BX, cable—a type of wiring commonly found in old houses—generally are grounded; the cable's flexible metal jacket serves the same purpose as a dedicated ground wire.

http://www.thisoldhouse.com/toh/m/article/0,,20065922,00.html

Like I said perfectly acceptable. Some of the older bx even have a thin copper wire added that serves the same purpose as your new bonding strip. Is the new stuff better and safer, of course. But grounding outlets like this is safer then non grounded outlets of the past. No one expects everyone to rewire there whole house to change an outlet.

Further to the below, there's a lot of misconception laced throughout the thread. There are a lot of Electrical Code wonks who would argue either side of this, but the bottom line that I've come up with after working for an electrician and spending inordinate amounts of time researching this is solely as it relates to replacing a couple of outlets:

- If you have old Armored Cable (typically known as BX) in good condition and correctly installed and

- If you can prove that you have continuous ground to the breaker box

- And you have a modern breaker box with appropriately rated breakers

- Then you should feel comfortable doing as described in the This Old House article.

If you're craving more detail, the problem is that:

- A lot of older BX installations were not great. In particular, there are points of failure where the cable is inserted into the older metal boxes. A bad connection there could mean that the connection between the box and cable is week or

- The cable was cut with a hacksaw or pliers and either a) knicked the wires inside or b) created a very tenuous ground path through the jacket or

- In the interim, someone has spliced in other cable in the middle of a run and failed to maintain ground correctly (e.g. spliced in romex, put in a plastic box, etc.)

The alternative would be that every time you replace an outlet, switch, etc. you would have to rewire back to the box. That's obviously not feasible in many cases. That said, if you have sketchy, older Bx or definitely if you have Knob and Tube, you'll be looking at fishing a new run.

ace11 said:
Sorry rowerg, I'm not wrong. Like I stated you might be confusing new codes for new building construction with retrofitting old work.
A copy and paste format this old house,

Old-fashioned two-prong receptacles connected to two-wire cables don't have the ground wires that protect people and electrical devices in case of a fault. Yet it is possible to retrofit a new three-prong or GFCI receptacle into the same outlet box without any rewiring, as long as the box itself is grounded.
Luckily, metal boxes attached to armored, or BX, cable—a type of wiring commonly found in old houses—generally are grounded; the cable's flexible metal jacket serves the same purpose as a dedicated ground wire.


http://www.thisoldhouse.com/toh/m/article/0,,20065922,00.html
Like I said perfectly acceptable. Some of the older bx even have a thin copper wire added that serves the same purpose as your new bonding strip. Is the new stuff better and safer, of course. But grounding outlets like this is safer then non grounded outlets of the past. No one expects everyone to rewire there whole house to change an outlet.

Actually, that's kind of backwards. The original Armored Cable was branded Bx. Kind of like band-aid, the name stuck. You'll find that the National Electrical Code that only AC (Armored Cable) and MC (Metal Clad) are used today. Modern AC is definitely much improved over the early Bx (insulation, continuous metal grounding strip, etc.), but in a replacement setting Bx CAN provide sufficient ground if the original installation was proper.

rowerg said:
Ace11- you are incorrect. not all bx is perfectly fine to use to ground a circuit, the early versions of bx (called ac) which are typically found in homes built in the era that many Maplewood homes were built do not have a bonded wire to carry the ground. NEC now requires that flexible armored cable have a bonded ground. If it doesn't, you risk the armor heating up like an oven element under a load.
jgberkley- while I understand that the GFCI primary purpose is not to replace two prong outlets, it is applicable here per code, NEC article 210-7d3 Sub-section (c) "A nongrounding-type receptacle(s) shall be permitted to be REPLACED with a grounding-type receptacle(s) where supplied through a ground fault circuit interupter".
In this application, you are not creating a ground, but you are making the circuit safer than a non-grounded regular three prong outlet.

Your right. Thats why an electrician is always a good idea, what catch 22 said is true except for the need for a newer box, older boxes are fine if hooked up correctly and a ground is a ground. Like I said, its safer then before, but not as safe as perfectly new. Its easy enough to check if you have a good ground. I believe the pre 1920 bx cable was called AC, it was blackish in color. ( it might have stood for aluminum clad? Not sure) The new AC cable is just a brand name that stuck ( Armour clad) , kind of like saying sheetrock instead of drywall. The extra wire that was used for the bonding was put in around the late 1940s. It was added for the reasons you stated.

As it relates to the box/panel, there are still houses in Maplewood with old fuse boxes. In the first house I bought, many of the fuses were ridiculously over-capacity (like 30 amps across the board). There are also a number of modern breaker boxes (Federal Pacific leaps to mind) that were found to be grossly unreliable. Sooo... agree with others that having a good electrician go over everything with you the first time around is by far the best course of action.

ace11 said:
Your right. Thats why an electrician is always a good idea, what catch 22 said is true except for the need for a newer box, older boxes are fine if hooked up correctly and a ground is a ground. Like I said, its safer then before, but not as safe as perfectly new. Its easy enough to check if you have a good ground. I believe the pre 1920 bx cable was called AC, it was blackish in color. ( it might have stood for aluminum clad? Not sure) The new AC cable is just a brand name that stuck ( Armour clad) , kind of like saying sheetrock instead of drywall. The extra wire that was used for the bonding was put in around the late 1940s. It was added for the reasons you stated.