Thanks, but I’m not in Denmark 
The reasons for running conduit can be many, but primarily it’s to protect conductors from damage. In locations such as warehouses, rigid steel is generally required. In residential or other interior applications, EMT or PVC is often permitted. Secondly, conduit allows ease of running multiple conductors to a single location for the purpose of branching out to other locations. Imagine the hassle of running 20 pieces of romex or other NMS cabling. Thirdly, conduit helps provide a grounding path for boxes and other devices. Fire prevention? Not so much, IMO. A shorted wire will burn through EMT like butter, and then you have hot slag to deal with. I’ve melted tempered tools by shorting conductors during work.
Well, I’m not expecting a high energy use up there, but I would like more outlets so there would be less running of cords. And I am thinking of two window air conditioning units. So I would be looking at 20 or more outlets, plus two high-amp ones to handle the window units.
And of course, first I need to get my 60amp service upgraded to 200amp or something…grr…
The sub-panel idea sounds very interesting.
This is the thing I was wondering about. I would have thought that the breaker would trip before the wires had a chance to get heated to that degree. In my experience with shorts, there’s a mini-explosion at the site of the short, then the breaker trips before the wire heats up to any great degree.
But let’s suppose the breaker does get stuck – what happens? I suspect the entire run of wire and anything connected to it will heat up until the weakest point of the circuit fails. What I don’t know is how long that might take, or where the likely point of failure is. What’s a typical scenario?
A sub-panel won’t do you any good if you only have a 60 Amp service to begin with.
You will also want to put each window unit on their own 20 amp circuit.
There isn’t a typical scenario since this is such a rare event. I suspect what would happen is that the wire itself will burn through and open like a fuse, except the wire itself can take a rather large load before it will burn open. I don’t have the numbers in front of me, but I’d guess that 12 gauge wire could probably handle over 60 amps for several seconds or minutes before it will open. The temp rating of conductors has more to do with the insulation than anything else. Example; If the insulation is only rated to for 75 degrees C then the limitation isn’t the copper conductor, it’s the insulation. Also, you need to derate for various types of applications.
Yes, which is why I will need to upgrade the service. Already right now the 60 amp is marginal IMPO.
I guess on a related note to the group, what is the absolute best thing which I can do to prevent the possibility of fires from overheating and/or shorts on a new construction?
I need to stop posting about technical stuff late at night… :smack:
Code is now calling for arc-fault breakers on circuits feeding bedrooms, and given time, I’d expect to seem them required for general areas like the living room. They sense the early milliseconds of an arc, such as one internal to a damaged extension cord, and kill the power before the arc has a chance to burn through the cord’s insulation and ignite curtains or bedding.
So, AFCI breakers will give an added measure of safety on the bedroom cicuits, and regular breakers keep on doing their thing as usual.
Looking forward to the day when you upgrade the service to 200 amps, specifying “Code Plus” will do wonders for overall safety and reliability. You can’t just tell an electrician you want Code Plus - it’s not something that comes in a box. Rather, it’s a metaphor for doing better than the basic minimums - things like 20-amp circuits with 12-gage wire where only 15 amps on 14 gage is required, powering each bedroom with its own dedicated circuit, rather than sharing a circuit among several rooms, using commercial-grade receptacles instead of the 49-cent cheapies, and so forth.
You’ll spend a bit more initially, but you’ll get a more robust and fault-tolerant system built with components that will last decades and you won’t knock the whole house into darkness the next time someone decides to turn on a hair dryer when the dishwasher is running.
I’d never heard of these things before this, but I’ve just done some reading about them. Sounds to me like it would be a smart thing to replace all the circuit breakers in the house with AFCI ones. Any reason not to, besides cost?
I’d imagine they could make life in the kitchen miserable if your old mixmaster’s motor sparks a bit, like most mixers tend to do. Everything in the kitchen should be protected by ground-fault (GFCI) breakers or receptacles anyway. Same goes for bathrooms and the garage - GFCIs are already required in those locations.
Room air conditioners will trip out an AFCI when they start up, so it’s strongly recommended they be fed by a dedicated circuit - most air conditioners need a 30-amp line anyway, so that exempts them from AFCI requirements - currently, AFCIs are only required on 15 or 20 amp bedroom circuits.
Some types of lighting dimmers will also nuisance-trip an AFCI. If you wire things right, the lighting will be a separate circuit from the receptacles anyway.
Yes, and do not run a 20 amp circuit for the lighting. Receptacles - OK, but not lighting. You don’t want the little 18-20 gauge wiring in the light fixtures on a 20 amp branch circuit.
Things you want on a separate circuit;
Bathroom outlet(s)
Bathroom exhaust fan if it is a light/heat/fan unit.
Outlet for AC unit
receptacles in each room
separate circuit for computer desk or entertainment center
outlet for portable heater to be plugged in
These are just suggestions for the type of work you plan on doing (expansion/remodel) not for the entire house.
Hold on, friend. How does 18-20 AWG zip cord know the difference between the banker’s desk at First Trust Officeplex, and your daughter’s desk at home? They will both melt if subject to anything less than a full fault, which will trip the OPD.
Were one to be undertaking a full rewiring project, I can imagine efficiencies to be realized by simply using #12 throughout.
“Now” is really the operant word. The 2002 NEC required AFCI protection in dwelling unit bedrooms per 210.12. 2005 NEC expanded the language, and the 2008 NEC will require them in most areas of 1 and 2 family dwellings. Before you ask for a cite, I don’t have my '08 book yet, and am relying on what I glean from Inspector Association meetings. 
Ultimately, it still comes down to what is required by the Authority Having Jurisdiction. If they approve knob and tube, have at it.
So, what’s the difference you ask?
One is where you work and the other is where you live. 
This seems best to me too except, of course, if you have a load that requires greater than 20 A.
Personnaly I don’t favor putting Romex in metal conduit at all for runs within walls. Bury a Romex pair in a steel tube, surrounded by insulation and things can get pretty hot. As someone mentioned above, you must derate the Romex if it has lass than the usual bare Romex air circulation.