Old house/ Not many grounds

tealflame

My house was built in 1900 and mainly has the old 2 wire non ground romex style wiring in it. Some of the wire looks like it has cloth over it and most looks like it has black paint or tar. Only some of the wiring is newer with grounds. I have a 100amp circuit breaker box. I bought this house without having an electrician looking at it first and was told it was a 200amp service by the seller which turns out to be wrong.

Anyway, I added some grounded outlets for my electronic equipment but my kitchen has no grounds for appliances. So I rewired the refrigerator outlet with new 14/2 romex right to the breaker box which should be plenty for just a refrigerator and is now grounded. I have another outlet that has three prongs but is not grounded since there is no ground wire. I had my microwave plugged into it all this time without knowing until I plugged in a surge protector that showed it was not protected.

Is it safe to plug a microwave into a non grounded 3 prong outlet? What is the easiest way to ground it without rewiring?

My problem is that I don't know how to fish wire through old plaster walls when the old wire is stapled or nailed to the studs inside the walls. I do not want to tear all my walls down to replace wiring. The refrigerator outlet and wiring wasn't too hard to replace since it was close to the floor. This other outlet is above the counter tops.

Thanks for any advice.

jbfan

You do not have to staple the wire.
Is the wire fed from the top or the bottom?
It takes a little practice, but you should be able to feed a new 20 amp circuit to the microwave.

__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"

joecaption

No one should ever buy a home without a home inspection done by an inspector that they hire no the home owner or realitor.
Simply looking at the main breaker would have told someone it was 100 amps not 200.
Has the main incoming line been upgraded or did someone just go buy a new panel and replace the old fuse box? The power company can tell you this info.
Does this panel have a ground wire running outside going to a ground rod?
How many breaker spaces are empty in the panel?
Any modern home over about 1000 sq. ft. should have 200 amp service so there's room for more breakers.

tealflame

I regret not having a full inspection because of the electrical, but too late for that now. Its a 1200 Sq. Ft. half twin home. 100amp service meter outside with grounding rod. Seller lived here 50 years and said it needed some updating. Next house I buy will have a full inspection for sure.

I plan to run a new romex to that outlet sometime but for now I may just move the microwave into the dining room where I have one grounded outlet.

I also noticed that there is door bell wiring with a transformer in the basement that has power to it. I have no door bell though, unless its behind the vinyl siding.

The main problem is the original wiring is very old and scary looking in the basement. Since my family and I live in this house, I plan to rewire 1 room at a time starting with the basement.

Do I need a permit to replace wire or is it only required for adding circuits? Would 14awg wire be ok? I don't think a microwave uses 15amps. My refrigerator uses about 5amps thats why I used 14awg wire for that.

AllanJ

You can run temporary ground wires (equipment grounding conductors) from locations where you substituted 3 prong receptacles, closely or somewhat or vaguely following the route of existing circuit wires or cables, down to the breaker panel.

Some circuits need to be 12 gauge 20 ampere. These include bathrooms (suggest a separate circuit for each, the laundry room or area (one), kitchen counters (two 20 amp circuits). Almost always you will need a permit to install/upgrade to these.

Check with your city regarding permits for just replacing existing wiring witht he same size.

__________________
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

plummen

So you use the sq footage to figure number of breakers required and size of service to feed it?
Personally I size an electrical service by the load thats placed upon it most of the time!
Generally there wouldnt be a ground wire going from panel to a ground rod outside,in my experiance the panel would be grounded to street side of water service.
The meter socket outside would be connected to a ground rod

mpoulton

Well that is sort of a location-specific kind of thing. Here in AZ, we use mostly exterior-mounted meter-mains. The N-G bond is in the panel, so that's where the grounding electrode connection is - but it's the same enclosure the meter is in. When I lived in Omaha, I remember that the newer house we had (mid 1990's) used an N-G bond at the meter socket and a 4-wire feed to the panel, while the older house (1920's) had the GEC connected in the panel like most of the rest of the country.

AllanJ

When calculating the required service for a house nowadays (load calculation per the NEC) the square footage of the house enters into that calculation. It's 3 watts per square foot.

Older homes might not have a ground rod but usually have a connection to an underground water pipe entering the house for use as the ground (grounding electrode). Nowadays that interconnection (grounding electrode conductor) must be at least #6 copper, use #4 copper for services over 100 amps, up to 200 amps, and clamped to the pipe within 5 feet of its entrance into the basement.

__________________
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

plummen

Figuring what the actual load on the system on an existing house is a more realistic way of sizing an electrical service .
What appliances does the house have/gas or electric heat/gas or electric water heater/central air or heat pump/garage or wood working shop???????
Just saying the house is 1000 sq ft therefore it needs a 200a service,is like saying the house is 1000 sq ft so it needs a 75,000 btu furnace and a 2 1/2t ac unit(just examples) without figuring the actual load on the system
The reason we run the ground to the street side of water service is so if somebody pulls the water meter to work on it you still have a ground for the electric service

TarheelTerp

If you don't plan to remodel the basement... this will work out fine.

With few exceptions you're better off doing 12ga (20Amp) everywhere.
Kitchens, Dining Rm, Baths, Garages, etc all require it.

14ga (15Amp) will be fine in many other areas (like bedrooms) and for lighting.

Permits are a local issue... but be prepared for inspections.
Especially when you do the service upgrade.

If (when) you make changes you must do them to current regulations.

OK. Get some help experienced too.

You'll come across all sorts of things.
In this vein it's worth having (paying!) someone to come in and make a plan for you to follow. A list, a set of instructions and sequencing.

hth

highdeserthome

If a house uses natural gas for hot water, cloth dryer, and cooking range and oven, why would it need more than 100 amp service, even 2,000 sq feet home.

Just the AC, frig, dishwasher will be the electric power hogs.

I even do some woodworking, demanding may be 30 amps momentarily peak. Figure one dust collector, a table saw and lights. One-man shop can't use much power at the same time.

tealflame

So I should have used 12/2 for a dedicated circuit to my refrigerator? I used 14/2.

I think 100amp service is enough for me for now. I ran 3 ac window units, dishwasher, refrigerator, washer and dryer already and no breakers popped. Everything is electric in my home except heat is oil in the winter.

I have to call the county to find out about permits to do electrical work, mainly just replacing wire and adding grounded outlets.

Thanks for everyones replies.

TarheelTerp

Have fun. Be safe.