Question about upgrading electrical

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Submitted by edna_mode on November 3, 2012 - 4:13pm

Hi there, thanks for all the great advice! Wondering if anyone has ever upgraded two pronged outlets across a whole house before (~1200sqft, late 50's construction). Any recommendations, advice or cost estimates? Is it possible to do this without tearing walls apart?

Submitted by spdrun on November 3, 2012 - 4:35pm.

I can't speak to CA, but in my family's apt in NJ that was built in 1950, they used cable with a ground connection built in and 2-prong outlets.

Basically, you need to test each outlet between hot (shorter prong) and the metal box with a test lamp. Ideally one that draws some power - say a 60W bulb with probes attached - not just a neon probe. If it lights up, then you have a good ground, and you can just use a self-grounding 3-prong outlet, or ground a regular 3-prong outlet to the box using a ground wire.

If not, then it's a different can of worms, and will be more expensive. You may be able to get away with GFCI breakers and 3-prong outlets (allowed under the Nat'l Electric Code, so long as the outlets are marked as "no ground").

What kind of wiring is in the house? Plastic Romex? Cloth? BX? Old cloth-and-rubber cable is hideous shite that should be replaced. The insulation tends to fall off if you so much as stare at it wrong.

Submitted by edna_mode on November 3, 2012 - 4:37pm.

Don't know the type of wiring as I was just touring houses. Had a bit of a horror moment in one house where all of the outlets were replaced in a late 50s/early 60s house with the T-type 3 pronged outlets -- that usually means 20A/110-120V circuits (standard residential is 15A/110-120V). Surprise!

Submitted by spdrun on November 3, 2012 - 4:43pm.

A device only draws as much amperage as it needs -- plugging a device with a 120V/15A plug into a 120V/20A outlet won't hurt anything. It just means that you can ALSO use a device that draws up to 20A. I'd be scared if I saw normal-sized outlets where one prong is horizontal, the other vertical. That means 240 voltZZZZ.

On the other hand ... my dad's first apartment in NYC had some outlets that were still on the city's direct-current grid, and looked exactly like normal outlets. Plugging in a lamp was fine. Plugging a TV set into one of them caused the TV's transformer to melt down.

Submitted by Hatfield on November 3, 2012 - 6:53pm.

edna_mode wrote:
Hi there, thanks for all the great advice! Wondering if anyone has ever upgraded two pronged outlets across a whole house before (~1200sqft, late 50's construction). Any recommendations, advice or cost estimates? Is it possible to do this without tearing walls apart?

One of my rental units is a 1929 era beach cottage that had been partially upgraded over the years, so it was a weird mix of romex and knob-n-tube. About a year ago I had all the old wiring ripped out and replaced with modern wiring, new switches, grounded outlets, GFI in the kitchen & bath, etc. I think I also had an additional circuit added in the kitchen. I got two estimates from licensed contractors. One was $8k, and the other was under $4. We went with the cheaper one and were very happy with the results. One other note: the electrical panel had been upgraded at some point. My understanding is that it's a big expensive PITA to replace the electrical panel, so hopefully yours is modern enough that you won't need to replace it.

Whether or not the walls need to be torn apart will depend greatly on the construction of your unit. If you're on a slab, yeah, they most likely will need to rip a channel in the wall to run new wiring down from the attic to switches and outlets. Most of the beach cottage has crawlspace below, and in those rooms they were able to fish new wire up to the outlet locations without cutting into the walls. Also, for ceiling lamp fixtures they may be able to keep the existing wiring if it's still in good condition.

Submitted by sdduuuude on November 5, 2012 - 10:09am.

spdrun wrote:
A device only draws as much amperage as it needs -- plugging a device with a 120V/15A plug into a 120V/20A outlet won't hurt anything. It just means that you can ALSO use a device that draws up to 20A. I'd be scared if I saw normal-sized outlets where one prong is horizontal, the other vertical. That means 240 voltZZZZ.

On the other hand ... my dad's first apartment in NYC had some outlets that were still on the city's direct-current grid, and looked exactly like normal outlets. Plugging in a lamp was fine. Plugging a TV set into one of them caused the TV's transformer to melt down.

The DC grid that Edison set up is still in service ?

Submitted by spdrun on November 5, 2012 - 11:32am.

Not anymore - the buildings that still need it use rectifiers. But Con Ed provided DC service into the early 2000s for some buildings.

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