this old house..electricity question

Randy Reeves · From: LaCrosse, Wisconsin, USA

I am looking at a house to purchase. everything looks good, but when the inspection report came back there was a red flag regarding the electricity. most if not all of the outlets in the house had no ground. the house is old and has the old two wire circuitry.
to me this is a defect. I believe it would be unsafe and dangerous to me and my equipment to plug in and play. the seller is having an electrician look at it.
my question: is this indeed a big problem? is it unsafe to plug in an amp? my gut tells me yes.
what say you all. your advice is needed.
thanks in advance.

Jeff Garden · From: Center Sandwich, New Hampshire, USA

Maybe I've been cheating death all these years, Randy, but I live in a 200 year old farmhouse with similar wiring to yours and have never had a problem with damage to equipment, the house, or myself. (I just have to make sure I'm not using the toaster oven when the amp is on!) I know in a perfect world all of the outlets should be grounded and those "3 to 2" converter plugs should be illegal but oh well, it works for me.

Michael Maddex · From: Northern New Mexico, USA

I don't see how any of us can analyze your house long-distance, but I will make a couple of comments. First, there is a reason why the code went from two-wire to three: Safety.

Randy Reeves · From: LaCrosse, Wisconsin, USA

thanks for the replies. of course I do not expect an analysis on this forum. I do welcome opinions,anecdotal experiences, problems encountered, such as electric noise. besides the obvious safety issues, can I damage my amps, computers, etc.
I have searched on line and found many topics related to two wire and remedial action. none regarding a musicians concern.

Dave Grafe · From: Hudson River Valley NY

IF the two-wire system is sound and properly installed you should have little or no problem.
1) the absence of a grounding wire will not damage your equipment in any way.
2) the danger to your person when playing an electrical instrument is primarily from touching a charged surface while also touching your plugged in guitar. As a rule there are no exposed charged surfaces in a normal residence (true whether the wiring is two-wire or three), so the danger is pretty much nill. If you are concerned about getting shocked from touching a microphone while playing guitar just make certain that all of the sound gear is plugged into the same THREE-WIRE power strip and the gear will be grounded together through the nuetral and signal wires, eliminating this risk.
The safety issues that the third wire addresses are not life-threatening unless your gear has a sudden internal meltdown, you are in a bathtub while using a toaster or washing dishes while handling running appliances. The third wire is an alternate path to ground in the case a short should pass energy to the outer surface of an electrical device.
The number of venues that we all regularly play that have this same defect in wiring is far more than we might surmise, I remember one very famous concert hall in Detroit that had the third wire installed throughout the building but it was never actually connected to a ground; nobody got killed but the amps and PA would play four or five radio stations when they were plugged in and turned on....

All this being said, virtually the same protection can be obtained if you install a modern GFI outlet in place of the standard two-prong duplex in any critical areas. It will not only protect from shocks at that outlet but any others that are in the wiring chain with it. I did that to all my kitchen outlets whenb I first purchased my late '50's, two-wire home. Now I can wash dishes and tune the radio at the same time with perfect impunity....

John Phinney · From: Long Beach California, USA

I live in a house that was built in 1928. When we moved in all the wiring was old knob and tube with only two prong outlets.

In the process of remodeling the kitchen we had to rewire the electrical to get it to pass local building codes. I had the electrician install another separate circuit for my studio's power at that time.

Because my studio is a Pro Tools setup with lots of outboard gear, midi boxes, keyboards, amps, computer, etc. I didn't feel confident that the knob and tube would handle the current demand without some kind of trouble.

The main light in the studio room is still powered by the knob and tube wiring, and when I'm recording guitars there is noticeable a hum that goes away when I turn off that light.

I'm no expert, but when I read a warning in the front of a manual that says you must use a grounded power supply with whatever it is for the sake of the gear's longevity I follow it.
_________________
GFI Ultra D-10 8x5/Sarno Freeloader/Telonics volume pedal/Fender Super Six Split Cab with a 1x15 BW

John Billings · From: Ohio, USA

Get an analyzer from Radio Shack. I used to work as the maintenance man in a machine/sheet metal shop. Guys were complaining about shocks. Some idiot had carelessly mixed up which terminals on the outlets he had attached wires to. Found a bunch of places where he put the neutral wire to the hot connection and visa versa.
My house is two wire. On outlets on the outside walls, I drilled a small hole thru the back of the outlet, and thru the outside wall. Drove in a ground stake, and ran a wire thru the wall to the outlet.

Bert Berthold · From: Peralta, New Mexico, USA

As Michael says "safety". Added 2 cents, as posted regarding hum w/new GK MB 200 amp factory tech.says not designed for 2 wire system.If an amp like my Twin Reverb has a ground switching switch it may eliminate hum.It also can eliminate sparks from jumping between your lips and a microphone when talking or singing .I believe this was where the term HOT LIPS came about.

Dave Grafe · From: Hudson River Valley NY

There you go, John has it all nailed down....

FYI when looking at a two-wire outlet in the wall the slightly larger blade should be installed on the left and should be connected to neutral, the smaller blade on the right connected to 120VAC. This is definitely worth checking and/or correcting in ALL residential wiring, including more modern three-wire installations, even new contruction sometimes is bad.

CrowBear Schmitt · From: Ariege, - PairO'knees, - France

when you have an electrician verify the ground (or installing it) ask him it's value
if he's a pro, he can confirm it's resistivity
100 ohms max/ 10 ohms is even better ( the lower the better)
the 30mv default current breakers work if the ground value is appropriate

Blake Hawkins · From: Florida

Please check your fuse box, or breaker box if it has
been updated and find out how many Amps service you have.
Old houses may have only 60 or 80. Most new
ones have 200 or more.
My house, built in 1991, has 200 Amp service.

If you have a breaker panel made by "Federal Pacific"
demand that it be replaced. They are a known fire hazzard. There is a lot of info on the internet
about that.
Also I have had personal experience with a Federal Pacific panel.

Cliff Kane · From: the late great golden state

My house (1928) is two wire knob and tube. The inspector told that me that if it is in good and unmodified condition it is safe and not a problem, but GFCI outlets should be installed in the bathroom and kitchen where shorts could occur. Our spa and central air unit are on GFCI outlets. It is easy to change an outlet to GFCI and this will add the same safety as a grounded outlet. Or you can change an outlet to a three wire outlet and run a wire to your kitchen or bathroom sink/faucet and use one of those grounding clamps to attach the wire to one of the pipes to make a ground. I would just go GFCI if you're worried. BTW, some insurers will not write policy for a house with knob-and tube wiring, regardless if it is in good safe condition.

What bothers me are places that have three wire "grounded" outlets attached to an ungrounded two wire system. People see the three wire outlet and assume that it is grounded when in fact it is not. I would much rather see a two wire outlet so that I know for sure that there is no ground. In a case like this you can just put a GFCI extension cord in front of it or replace the outlet.

John Billings · From: Ohio, USA

"If you have a breaker panel made by "Federal Pacific"
demand that it be replaced. "
Abdo-lutely! I've changed out a few in an allotment near here myself. I don't think you can buy replacement breakers for them anymore.
If the house, by chance, used Greenfield electrical tubing, I believe that can be grounded. It's been a while!

Don McGregor · From: Memphis, Tennessee

As many household appliances, such as alarm clocks, phone chargers, and table and floor lamps, do not require three prong outlets, the old, two wire system is fine for much of my house. There is no reason to re-wire the whole house. I have, as others have discussed, installed GFCI's in bathrooms and in the kitchen. As we were remodeling downstairs, it was easy to go ahead and re-wire up-to-date wiring in my studio, downstairs bath, and my wife's office.
You don't need to re-wire the entire house, but it is worth it to think about having new, dedicated lines installed in critical areas, such as a workshop, or recording studio.

Randy Reeves · From: LaCrosse, Wisconsin, USA

thank you gentlemen. your posts are informative and helpful. thanks.

Bill Ladd · From: Wilmington, NC, USA

I'm a licensed master electrician and electrical contractor. I sometimes find myself at loggerheads with home inspectors and insurers over code issues.

The National Electrical Code specifies that three prong receptacles may be used in a two-wire system if a GFCI receptacle or circuit breaker is placed at the start of a given receptacle branch circuit [NEC section 406.3(D)(3)].

This works because the GFCI senses the current flowing from hot to neutral. Any imbalance and the GFCI trips the circuit. So if your metal-encased electrical device suddenly becomes energized by the hot wire being nicked and touching the case, the GFCI will sense it and trip immediately.

As far as running a ground wire to a water pipe, unfortunately, it doesn't quite work that way. Supplemental grounds such as cold water pipes and made electrodes (driven rods, plates, grounding rings, steel in the poured footer, etc) are there to provide current surge (lightning or utility created surges) potential to earth, but they are of too high resistance to provide effective current fault pathways. According to NEC section 250.4(A)(5): "Earth is not an effective ground-fault current path."

According to [250.2 and 250.4(A)(4) and (5)] -- "To quickly remove dangerous touch voltage on metal parts from a ground fault, the fault current path must have sufficiently low impedance to allow the fault current to quickly rise to a level that will open the branch-circuit overcurrent protection device."

That means you need to run that green wire to the first point of attachment from the utility in the building and bond to the incoming neutral provided by the utility. That'll give you the current path you need to sense the fault and trip the breaker.

Any more specific questions, please feel free to PM me.

Travis Hillis · From: Nashville TN, USA

Our house is 70 years old, and ungrounded. A few weeks ago I got shocked very bad...went and got a battery powered Vox DA-5 amp. Oh Well

Personaly, I will never plug into a ungrounded outlet. People have died that way...

Randy Reeves · From: LaCrosse, Wisconsin, USA

Bill. really appreciate the post. thumbs up.
an afternoon on google search and a cool drink along with all your replies has me pretty well informed.
the cool drink quenched my thirst and the posts have eased my stress.
Travis, having been a lighting tech in a museum for the last sixteen years I have had plenty of shocks working with modern-art-electric-found artworks.

it really has been a long time since the 'hot lip' days in the early years. what has changed? PA systems?

Forum Index > Electronics		Next oldest topic :: Next newest topic