two wire houses with no ground

[Stevenfyeager]

We always work for customers who have the old two wire romex at times. In a remodeling job, how important is it to suggest replacing the old two wire (no ground) when the opportunity comes? For example, a homeowner is removing most wall drywall (no ceilings) in several rooms. How much safer is 3 wire? In a big house this could cost a lot to replace even with bare walls. How much of a safety issue is it? Thank you

 

[jaylectricity]

Just how important is a matter of opinion. But if you have the walls down there will be no cheaper time to fix it than right now. If the walls go back up it could be another 20 years before they come down again.

 

[K8MHZ]

It's pretty important to the State of Michigan.

Their rules say if you expose wiring by removing drywall, that wiring must be brought up to the current electrical code. That's a building code rule. The code the wiring has to be brought up to is the electrical code, of course.

 

[growler]

Just how important is a matter of opinion. But if you have the walls down there will be no cheaper time to fix it than right now. If the walls go back up it could be another 20 years before they come down again.

If it were only another 20 years until that sheetrock comes down again that wouldn't be to bad. The reality of the situation is much worse. The main reasons sheetrock is removed is to repair damage ( termite or other ) and install new insulation but once that's done it could easily be another 40-50 or even 60 years before there is another reason to remove that sheetrock other than a rewire ( providing they don't use Chineese sheetrock).

 

[480sparky]

Some building codes require any opened ceilings / walls must be brought up to current codes. Even if it's not required, I'd make a strong case for rewiring as that's when it's going to be the cheapest and easiest.

 

[ptonsparky]

Can't be a better time than now. It won't get cheaper either.

 

[user 100]

If the walls are going to be opened up anyway, and if the customer can afford it or is willing to afford it, it should be strongly suggested. But if they can't or won't bite, I see no problem w/ leaving it if it is in good shape. I have found that the old, post 1940s nm w/ the woven tar painted jacket that has the type tw insulation on the conductors tends to be in good shape when uncovered, and the only time the tw seems to fail is when it is exposed to the heat from an overlamped fixture ceiling box. There would be no real benefit with new nm as far as that insulation is concerned-Remember that even today with 90c wire in new nm, we still use the 60 degree column. Anything older than tw really needs to be replaced, the nm w/ rw tends to be a little problematic.

As for concerns about about lack of an egc, look at it this way-the egc is largely unnecessary in a home because most every thing has a 1-15 cord cap. If really concerned about safety, see if they will go for gfci's.

 

[Tony S]

OK a basic question, what’s the cost difference?

 

[DrSparks]

If the walls are going to be opened up anyway, and if the customer can afford it or is willing to afford it, it should be strongly suggested. But if they can't or won't bite, I see no problem w/ leaving it if it is in good shape. I have found that the old, post 1940s nm w/ the woven tar painted jacket that has the type tw insulation on the conductors tends to be in good shape when uncovered, and the only time the tw seems to fail is when it is exposed to the heat from an overlamped fixture ceiling box. There would be no real benefit with new nm as far as that insulation is concerned-Remember that even today with 90c wire in new nm, we still use the 60 degree column. Anything older than tw really needs to be replaced, the nm w/ rw tends to be a little problematic.

As for concerns about about lack of an egc, look at it this way-the egc is largely unnecessary in a home because most every thing has a 1-15 cord cap. If really concerned about safety, see if they will go for gfci's.

I definitely agree. I've had so much TWN crack on me in ceiling fixtures. I use the liquid tape to fix 'em--several coats.

As for replacing the wires altogether, it may not be necessary or even cost-effective if the walls aren't being opened up. It really depends upon the point of usage. In the kitchen, bathroom, laundry, garage, etc. I would recommend modern wiring, but bedrooms and living rooms, maybe not so much. Code still allows non-grounding-type receps to be replaced with the same if there is no available equipment ground. Most electronics and even small appliances are double-insulated and don't require a ground. However, the problem arises with power strips. Most of them have an EG, so what residents will do to plug them in is either break the ground prong off or use a grounding adapter to bypass it. This creates a potential for electrocution because it allows a three-prong appliance to be plugged in, which requires an EG--which generally means it is not double insulated. Your other options are to either replace all the receps with GFCIs and label "No Equipment Ground" or fish a #12 solid bare copper wire to each box from the nearest accessible EGC. The latter is much less expensive, IMO, to do.

 

[480sparky]

..... or fish a #12 solid bare copper wire ......

Bare? Why? Just use green THHN and call it a day.

 

[DrSparks]

yes, you could use green THHN, but IDK about calling it a day. Anyway, here it is:

250.130(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor
of a grounding-type receptacle or a branch-circuit extension
shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system
as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure
where the branch circuit for the receptacle or
branch circuit originates
(4) To an equipment grounding conductor that is part of
another branch circuit that originates from the enclosure
where the branch circuit for the receptacle or
branch circuit originates [ROP 5–209]
(5) For grounded systems, the grounded service conductor
within the service equipment enclosure
(6) For ungrounded systems, the grounding terminal bar
within the service equipment enclosure
Informational Note: See 406.4(D) for the use of a groundfault
circuit-interrupting type of receptacle.

 

[readydave8]

I very often see 3/prong receptacles in older 2/wire homes, nothing hooked to ground screw (or occassionally neutral jumped to ground screw), so my perception is that there is a very high demand for 3/prong receptacles. According to the situation, but in general I would lobby strongly for rewire if several walls were to be opened, whoever finishes those walls can at the same time repair any damage done during rewire of otherwise untouched walls.

 

[readydave8]

replace all the receps with GFCIs and label "No Equipment Ground"

and explain to the customer what he is and is not allowed to plug in to them

 

[GoldDigger]

Unless the existing neutrals are cross wired you should be able to feed some of the receptacles with the feed through from the first one in line.
The package should have more than one sticker to allow that.

 

[480sparky]

I very often see 3/prong receptacles in older 2/wire homes, nothing hooked to ground screw (or occassionally neutral jumped to ground screw), so my perception is that there is a very high demand for 3/prong receptacles..........

Grounded receps at the home center: 49¢.
Ungrounded receps at the home center: $2.99.


You do the math.

 

[user 100]

..........Your other options are to either replace all the receps with GFCIs and label "No Equipment Ground" or fish a #12 solid bare copper wire to each box from the nearest accessible EGC. The latter is much less expensive, IMO, to do.

If we were going to be adding that separate egc to a few receptacles, it may be worth it, but anything more than that, imho, we should really just try to sell the customer on some new rope. If we can run an extra egc, many times we could just as easily cut (and I do mean cutting- fishing new cable utilizing old nm when the old stuff is stapled is not going to happen) the old mess out of the way and run some new nm with its own egc and give the h.o. some new ccc's also. One thing I don't like about the added egc method is packing yet another splice in sometimes already tight gem boxes. It's true that gfcis are a tight fit in those old boxes, but you (usually) only have deal with that in one box per circuit to be protected or you can do gfci breakers.

Of course we could keep the hatfield hatflex and install deeper boxes, and remake the old joints and tie together the new added egc's, but if one is going to go thru all that trouble, just give them new wire, or gfci the legacy stuff. The separate egc has its place-it was done quite a bit in the days before nm/with egc became prevalent, and it was (and is) certainly better than nothing.

 

[electricguy61]

It's true that most folks don't need the 3rd prong, but when they do, it frustrating not to have it. Also, in my experience it's the connections that fail 99% of the time.

The labor to install just a ground wire isn't much different then the labor to install new nm cable (and the coresponding wire connections). If they can afford to open the walls, they can afford a rewire.

 

[DrSparks]

It's true that gfcis are a tight fit in those old boxes...

They make low profile GFCIs, although they are a bit more expensive. Still probably cheaper than a complete rewire, especially if you are able to protect receps downstream.