Of course, with CF and LED bulbs the lighting current demands have drastically decreased.

As for rewiring, there are going to have to be holes cut in the walls, but you don't have to take everything down to the studs. What you're going to need is likely a couple of contractors. I've had electricians who were good about not cutting too many holes or ones in bad places, but I've never seen one to fix the damage he made. If this is an older house with real plaster walls, it will likely take special skills to patch things up again.

Ron, the walls are some sort of cement board with maybe a plaster skim -- so I think it would be difficult to patch holes but I am not sure.

I've gone to LEDs in all my light fixtures, and all ceiling fixtures have been replaced. I don't understand how the wiring would degrade though.

I also don't understand the implications of using a GFI marked "no equipment ground". I think I understand GFI, but what are the drawbacks of no equipment ground for modern electronics -- computers, TVs, etc?

Correct, modern CF and LED conversions produce lots of light with very little heat. The problem is in old houses that years of use with 100 or even 150 watt incandescent lamps have already degraded the wire insulation above the luminaires. I've taken down old devices to find the insulation cracking off -- and not just on old rubber insulated wire.

You're absolutely right that not having a ground isn't great. For one thing, surge suppressors don't work too well without one. But if none is present in the wiring, what are you going to do until you can rewire?

Tying the ground to neutral isn't safe, though some homeowners do it, either because they don't know better, or because they want fool those cheap neon light receptacle testers into showing "all OK."

The big benefit to using a GFI on an ungrounded circuit is that it guards against shock from equipment ground faults, even without the ground being connected. It senses an imbalance between current on the hot and neutral wires (which happens when there's a ground fault) and turns off the power.

The "no equipment ground" label is used because the GFI is a 3-pin device. It notifies users who plug in appliances that the appliances they're connecting aren't grounded, even though the plug's ground pin engages the receptacle's.

Thanks DavidR, the picture is clearer now.

A plaster skim is probably over "blue board" which is a drywall product that's probably not cement. But, by and large, anything can be patched. I've seen rewire done in old slat-lath/brown plaster/white plaster walls. Any of the drywall technologies are going to be easy.

GFCI, as David points out, primarily provides for occupant protection. It measures the power that goes-out-of the receptacle and compares it to that which goes-in-to. If it rises above a few milliamps, it trips. The assumption that current that goes elsewhere is probably up to no good (like passing through a human on its way to some other ground). Of course, it's not foolproof. If you cut a cord and grab on to the white and black wires with opposite hands, the flow goes right back to the GFCI and it thinks everything is OK. You'll probably be in cardiac arrest.

The "no equipment ground" thing is that the ground pin on the receptacle does provide other advantages other than occupant safety and it's warning you that those are not present.

Seems like I need to start saving my pennies to rewire the whole house; although I hate the thought, I guess it is a better move than making do with GFIs. Good point, at least the walls aren't lath/plaster (they, and the ceilings, really are cement board -- the homes were modular pre-fab shipped here by rail and assembled on site in 1941).

I rewired my entire 1891 home, including installing a new load center. The original wiring was all BX, from a 30 amp, 110 volt fuse box, later upgraded to a 60 amp, 240 volt fuse box. I ran new emt conduit up from the basement inside the walls to the location I wanted the new receptacles, on the first floor. I did the same from the attic to the second floor. I also ran flexible conduit in the ceiling of the first floor, to put in "eyeball" spotlights, and ran that conduit down to the basement. The most difficult part was running a large diameter emt all the way from the basement to the attic for a sub panel, to power the attic and second floor outlets. This was done without doing any damage to the wall surfaces.

After I was finished, I had it all inspected by a licensed electrician, who changed the meter, meter pan, and ran wires from the meter to the new load center.

Interestingly, there was no evidence of post and tube wiring; I guess the BX which ran to the old 30 amp fuse box was the oldest wire in the house.

I can bet you probably had some gas light piping in the house unless it was previously removed. I'd double check that has been disconnected. My wife found in an old house she was living in that the piping was not only there, but still plumbed to the city gas lines and eventually sprang a leak (not bad for 90 year pipes) even though the gas sconces were long gone and capped over.

When I lived in a condo, converted from a 1920s apartment in Chicago, I did find gas piping through which wires had been pulled! But no gas lighting in my current house, although there is piped-in gas which feeds the converted coal boiler.

I am going to take a different point of view. Rather than saving pennies for a complete rewire along with the service panel replacement, just have the new service panel installed and reconnect the existing circuits. If you know what circuits you want/need added because you need grounded circuits, go ahead and add them at the same time. Otherwise, just have the electrician come back and add a couple more when the need arises.

When the new service is installed, it might pay to have some or all existing circuits intercepted in a limited number of large junction boxes and new runs make from there to the panel. That was done in one home that I owned when new service installed where most of the cables ran through the attic and down the walls (1950ish slab home with 120/240, 3 ph originally). Part of the reason that worked well was due to consolidation of sub panel wiring to the new service panel, but there were other reasons related to access. At the same time the panel was installed, the electrician pulled a few "spares" from the new panel to those big junction boxes in the attic so it would be a snap to add additional circuits later. (No crawling over to the wall/roof junction under the hip roof, just sitting up on a piece of plywood in a relatively tall part of the attic space.)

You probably have what is called "rock lath" walls. That is what I have in my 1949 home and my parents paid extra for (over drywall) in the home that they had built in 1959. There are different versions. The 1949 version has holes to key the first plaster coat. I understand that later they figured out that was not necessary due to the chemistry of the bonding between the plaster and rock lath so that might explain the lack of holes in the 1959 version.

Rock lath might be the only reason to do the whole rewire at once, if you can find a reasonably-priced plasterer. We were able to get one, at surprisingly reasonable cost, to do wall and ceiling repairs in our home. Even in major metropolitan areas, I think it is becoming very difficult to find plaster pros. Even if you can find just one, they are tied up in major historic renovations. The trouble with little plaster jobs is that the work requires at least three trips letting the coats dry between visits (as little as a day). If you have a bunch of work to be done it sometimes won't cost you much more than fixing one crack or hole. On the other hand, maybe you can figure out how to do it yourself. Like a lot of finish work, it takes some practice to get a good look and will take a lot longer for a homeowner to do than a practiced pro.