i have a kenwood ka-9100 amp. should i ground the lug on the back of the unit (orriginally intended for phone grd wire) to a cold water pipe? along with everything else that uses 110ac
The amp only need be grounded if that was a safety requirement of the original design. If it has a 3 core mains lead then it should be grounded via that for safety.
The ground terminal on the back is as you say for use with a record deck. It's not a mains safety earth point.
Unless you have hum or ground loop issues I would leave well alone.
The ground terminal on the back is as you say for use with a record deck. It's not a mains safety earth point.
Unless you have hum or ground loop issues I would leave well alone.
Remember, one side of the plug IS connected to the water pipes back at the fuse box. Of course, with old outlets, they may not be polarized and you may not know which is neutral and which is ground. It really is far past time to rewire the house before it burns down.
I just rewired my entire house 7 years ago and have to agree with tvrgeek. Get rid of that knob and tube asap or hum is going to be the least of your issues.
Agreed. Knob and tube is obselete. Even old houses built to NEC standards can be easily upgraded (it's my "second" job to do just that), but knob and tube has to go. There is no provision for ground.
However, a ground fault protector will still work with ungrounded wiring. But it is a stopgap measure.
I have seen people connect the ground to the neutral and it works, but it is nowhere near as safe as grounded wiring. Not replacing knob and tube wiring is just asking for a fire or electrocution. Most of it is not even polarized!
Many Thanks for the replies
i just bought the place 3 months ago and been living here for the past 2 weeks. I havent even finished the painting! yes, rewiring is the ticket. The reason why i asked, is the house i was living in san francisco had the same old knb and tube. i replaced most of the outlets with 3 prong and ran a separate ground wire to pipes.prior to doing that, i used to get slight shocks on one of our computers. when i got an amp long time ago, a kenwood ka-907, when i hooked up the turntable, i noticed something was amiss.The needle would load up after a couple of minutes of what appeared to be dust, dirt, vinyl material, etc. and when i lifted the tonearm off the album?......POWWW... that sounded like a howitzer thru the speakers!!!.....thats WITH the turntable ground wire attached to the amp lug. someone suggested i ground the amp case to ground and that took care of that. that was 20 years ago. the only hum i get is when i hook the computer up to the tape input, just once so forget that. But thanks for your advice!!
i just bought the place 3 months ago and been living here for the past 2 weeks. I havent even finished the painting! yes, rewiring is the ticket. The reason why i asked, is the house i was living in san francisco had the same old knb and tube. i replaced most of the outlets with 3 prong and ran a separate ground wire to pipes.prior to doing that, i used to get slight shocks on one of our computers. when i got an amp long time ago, a kenwood ka-907, when i hooked up the turntable, i noticed something was amiss.The needle would load up after a couple of minutes of what appeared to be dust, dirt, vinyl material, etc. and when i lifted the tonearm off the album?......POWWW... that sounded like a howitzer thru the speakers!!!.....thats WITH the turntable ground wire attached to the amp lug. someone suggested i ground the amp case to ground and that took care of that. that was 20 years ago. the only hum i get is when i hook the computer up to the tape input, just once so forget that. But thanks for your advice!!
So you have experience with ungrounded electrical service. Would you agree that it should be replaced, or at least modified, ASAP?
What were you using as a ground?
It's not unusual for plumbers or painters to disconnect the ground wire and fail to reconnect it, or reconnect it improperly.
What were you using as a ground?
It's not unusual for plumbers or painters to disconnect the ground wire and fail to reconnect it, or reconnect it improperly.
You wouldn't get away with that here in the UK - your electricity supplier would disconnect you for having such unsafe wiring. You are living in a death trap until you have it rewired.
Just about anything original can be "grandfathered" in as long as it works in my area. I have never seen knob and tube wiring in the Chicagoland area, but I have a seen it in areas that conform to the American Electrical Code. And knob and tube wiring can even work with ground fault interrupters. Furthermore, an ungrounded circuit that uses polarized outlets and is fed from a properly grounded and wired service, is safe. It is also obselete.
Older houses in my area have non-polarized ungrounded outlets, sometimes even in the kitchen. They often also have too few circuits, sometimes too few outlets per room (like one outlet per room), and even cloth insulation wire with asbestos. If the house conformed to the National Electrical Code when it was built, it's usually pretty easy to upgrade and renovate the wiring.
If you have no grounded outlets in the room - it is deadly and illegal to add your own ground to that room. radiators are insulated with thick paint to keep the ground point away from people.
It's either everything or nothing - to keep deadly voltage differences away.
It's either everything or nothing - to keep deadly voltage differences away.
My house is over 100 years old, and has a bastard combo of post and tube and more modern Romex. The sound in the living room suffers, due to a lack of 3rd wire ground and wide separation of feed and return conductors. Rewiring (a room at a time) is definitely in the list of improvements...
Connecting a ground wire to a radiator isn't something that anybody with any sense would do.
An appliance with an ungrounded plug that is plugged into a polarised ungrounded outlet is safe, if the outlet is correctly wired and if the service is grounded correctly.
In houses constructed to NEC standards, THHN wire is installed in conduit (EMT). The conduit is ground. There is a separate neutral wire (the "designated conductor"). You can remove an ancient ungrounded non-polarized outlet and install a polarized grounded outlet (you have to wire it correctly 😉 ) and it will in fact work as designed.
Might I recommend adding a new circuit to your house when you rewire that room? Putting sensitive electronic equipment on a dedicated or lightly loaded circuit wil greatly reduce noise from the line and voltage fluctuations.
Just installed some knob and tube myself....
Its the hot wire of an electric fence to keep the cattle and horses (and unwary women and children <<insert evil laughter here>>) off the wire. Underground through poly tubing past any gates and strung on ceramic stand-offs at cow nose height along the fence. Pulsed about 10kV but very low joule every couple of seconds. Single wire, earth return. Works a treat.
However, its hard to believe that similar point to point wiring with what must be seriously aged and unreliable insulation still exists in houses. Its hard enough maintaining point to point in someone else's audio equipment let alone a whole house. You have my sympathy.
Its the hot wire of an electric fence to keep the cattle and horses (and unwary women and children <<insert evil laughter here>>) off the wire. Underground through poly tubing past any gates and strung on ceramic stand-offs at cow nose height along the fence. Pulsed about 10kV but very low joule every couple of seconds. Single wire, earth return. Works a treat.
However, its hard to believe that similar point to point wiring with what must be seriously aged and unreliable insulation still exists in houses. Its hard enough maintaining point to point in someone else's audio equipment let alone a whole house. You have my sympathy.
Millions of US homes were wired with Knob & Tube and are still standing!
The three problem area's are:
a] Replacing the original fuses with larger fuses.
b] Replacing components takes skill because the 70 to 90 year old wires are fragile.
c] Covering the wires with in-wall insulation.
GFCI (Ground Fault Circuit Interrupter) receptacles are now available to fit in the old outlet boxes.
The newest 2011 NEC code book covers Knob & Tube wiring in Article 394. For extensions of existing installations.
But it's not without disadvantages:
http://en.wikipedia.org/wiki/Knob_and_tube_wiring
The three problem area's are:
a] Replacing the original fuses with larger fuses.
b] Replacing components takes skill because the 70 to 90 year old wires are fragile.
c] Covering the wires with in-wall insulation.
GFCI (Ground Fault Circuit Interrupter) receptacles are now available to fit in the old outlet boxes.
The newest 2011 NEC code book covers Knob & Tube wiring in Article 394. For extensions of existing installations.
But it's not without disadvantages:
http://en.wikipedia.org/wiki/Knob_and_tube_wiring
Last edited:
What drives me crazy about the old post and tube stuff is the way people just casually tapped in to run another circuit, making it really hard to figure out where everything goes. I expect the rewiring will unsnarl a lot of cluster***ks. Fortunately, I have a basement, so everything is readily accessible. What I need to do now is to buy a copy of the county electrical code, so I can put my staples, junction boxes, etc. In the right places.
Unless the house is 100% original wiring, you will almost certainly find something that is really wrong.
My house was built in 1960 with NEC wiring (conduit, no romex allowed) and whoever installed the new stovetop hard wired an extension chord to the house wiring! Also the 240 volt 30 ampere feed for the AC compressor was 10 gauge THHN unfused!
The original wiring that was left unmolested was 100% functional and safe, although there were not nearly enough circuits and most of the outlets were ungrounded.
You can buy a tutorial, Wiring Simplified, at Menards. I highly recommend it; it will answer many questions and give you some ideas.
Your house is wired according to the AEC (American Electrical Code). The romex gave it away. 😉
What is your fusebox like? Updated with breakers? Are there extra spaces for more circuits?
I highly recommend that you provide a dedicated circuit for your audio equipment. That is the best way to isolate it from the noise and voltage droops in other household circuits. Then you won't have to buy one of those fancy pants "audiophile" outlets either. 😛
Your house is wired according to the AEC (American Electrical Code). The romex gave it away.
It's really NEC (National Electrical Code). The code book is updated every 3 years. But states and cities are free to choose what year book. They can also add to, or delete from the code book. Chicago and New york city have lots of special rules.
About 50 or 60 years ago, many houses were updated from fuse boxes to circuit breaker boxes. Often of the Federal Pacific brand, these FP boxes have become very unreliable and if other electrical work is being done and a new breaker box (panel-board) to the list.
It's really NEC (National Electrical Code). The code book is updated every 3 years. But states and cities are free to choose what year book. They can also add to, or delete from the code book. Chicago and New york city have lots of special rules.
About 50 or 60 years ago, many houses were updated from fuse boxes to circuit breaker boxes. Often of the Federal Pacific brand, these FP boxes have become very unreliable and if other electrical work is being done and a new breaker box (panel-board) to the list.
My house is a chimerical mess, with several generations worth of hodgepodge. Strangely enough, I have a fairly modern 200A entry panel, with a good deal of breaker space. I had a modern 120A subpanel installed in the basement, though there is still some tweaking to be done there.
I'll look into that tutorial. I also have some beginning wiring manuals. After a short search, I was able to download the 2010 electrical code. At any rate, I intend to piece things in a circuit at a time.
I'll look into that tutorial. I also have some beginning wiring manuals. After a short search, I was able to download the 2010 electrical code. At any rate, I intend to piece things in a circuit at a time.
- Status
- Not open for further replies.