Help: Ceiling Light Fixture

Hello, I need to replace my ceiling light fixture in a room in my house. It looks very old and in bad condition ( including wires ). You can look at these pictures I uploaded if you like and thank you for your help.
http://img255.imageshack.us/i/dscf4677.jpg/
http://img137.imageshack.us/i/dscf4680.jpg/
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Thank you again for your time.

 

Let me guess, your house was built prior to 1955 and you have knob and tube wiring. Or, at least, you do not have 3-wire wiring. Many people will say, get an electrician. I suggest you get the current code book (about $10 at big box stores). Study it. If you still don't have a clue of what to do, then call the electrician.

John

 

I would get a professional electricians opinion on the general condition of the housing wire as a whole, if that's typical for your home it would be a serious consideration to have it rewired, it is costly, but with the age of that wiring you're talking basic saftey and meeting local code.

From the basic looks of the fixture though you have two wires, for a rudimentary fixture replacement there really aren't any considerations to take into account if you know which one is live and which one is neutral.

If you don't know how to determine this yourself you shouldn't be messing with it.

 

Thanks for your advice. I really appreciate it. How may I find this code book? What is it called exactly? Yes, this house was built in the 40's and it only has the 2 wiring system as far as I know. I don't know a lot about wiring or electronics and such so do you think the code book would still help me, or are there other books I could read that are good for a beginner like me?

Thanks again

 

WOW the mods are a bit slack today. This hasn't been locked yet.

 

No jeep, not really. The tutorials here will explain general electronics theory, but if you're talking about home electrical systems you have to go through school and become certified for that for both legal and common sense safety reasons.

You should under NO circumstances touch any of the wiring in your home unless you know exactly what you're doing and the local laws. It doesn't matter what you read on a website or someone here tells you offhand, if you YOURSELF don't know you have a problem because you're the one responsible in the end, for property damage, and worse if you do something that hurts someone else you're legally liable for that, just think murder charges if someone dies.

Hopefully that scares you enough to call an electrician, if you can't afford that, you better think twice before you touch what you don't know about.

 

Thanks for all your advice. It is good. Yes, as for wiring in the house this is pretty much typical and most likely doesn't meet local code. If this has to be replaced entirely, I wouldn't be able to do that without knowing exactly what to do.

 

Try about $75 for the proper NFPA-70, 2008 is the current edition, 2011 is about out so you may find some bargains. Not a lot has been changed since the 2005 edition so even that would be fine for most reference.

Problem here is I wouldn't advise ANYONE to so much as touch knob & tube wiring, it's supported by the initial tension it had and has probably sagged a bit over the years, disturbing it could be asking for a disaster.

The good news? That isn't knob and tube, just conventional Romex somebody's made a mess of. The wire looks to have seen its share of heat and should probably be replaced for some distance back from the fixture.

Aside from the often oddball conduit bends I'm glad I only have to mess about with commercial electric.

 

Why? The book I suggested is not only more readily available and cheaper, it is adequate to address the purpose for which it was recommended.

John

 

I didn't see reference to any particular book. I have to work with the NFPA-70, better known as "The National Electrical Code" and accepted as such across the United States however a beginner would get lost in it pretty quickly.
http://en.wikipedia.org/wiki/National_Electrical_Code

I'll assume you're talking about one of those "Home Wiring Made Simple" books?

Nothing wrong with them for a problem like this, I'm still a bit leery about the condition of the insulation on the feed wires though.

 

I was referring to "Wiring Simplified." It is based on the current NEC. The version I have is the 2008 version (42nd edition) by Richter, Schwan, and Hartwell, Park Publishing,Inc., 2008.

It is in the electrical section and any "Sales Associate" there can find it for you. Of course, it might be much easier just to look for oneself than to find a sales associate.

John

 

There is that problem, plus that with no ground handy, checking for the hot conductor is pretty difficult. Of course, I have seen electricians do house wiring and mix the black and white wires. Some inspector had signed off on it, too.

I saw one house with knot and tube wiring in which modern romex had been added for some branches. Same 4 fuse 100 amp service, and the romex had been soldered with plumber's acid core solder. I could feel that house catching fire as soon as I saw that mess.

 

Probably a plumber that wired it.

In any case I'd kill the entire house power or in the least get one of those sensing bugs - then again it's just too easy to accidentally touch the hot wire in these situations. There's the fact that a lot of the earlier houses ran hot to the fixture and switched the neutral.

Gotcha' on the book, sounds kind of like the handy reference one of our big suppliers hands out for free. I don't know about you but I have trouble remembering things like conduit fill for 1-1/4" and it's a heck of a lot easier to find in that small book.

 

Yes the insulation above the ceiling over those particular wires may be in dire need of change. Thank you for your replies so far and thank you for the link and the descriptive information about the code book because I am new to all of this. These posts are certainly helping me more though and thanks again for your time posting.

 

Yea, don't let us scare you, us electricians like to trade stories as best as the rest of them but one thing stands us apart from most other professionals - we take extreme care and pride in our work to ensure the safety of our customers and their buildings.

If the cable guy goofs worst case is you go without the internet and reruns of M*A*S*H for a night.

I'm up early and hate it, gotta' be in by 8:00 or so this morning and I take my sweet time waking up.

The fire alarm people are coming to hopefully finally fix all the problems I've found over the past two years. Complex system in a 250,000 square foot building and I'm the only one that's taken the time to figure out how it all works. Sometime last weekend the control panel went haywire and thinks there's a fire, it even turned on the 40 HP fire pump which drained my entire 205,000 gallon backup tank of water but to where is still a mystery. I could probably figure it all out but there are times you've got to draw lines in the sand and put the responsibility on someone else. According to the code books I'm allowed to work on any of the system except the actual sprinkler head plumbing but I don't have the time as it has several problems that need to be fixed.

In addition another one of my favorite meetings occurs this morning - some salesmen claiming they can greatly reduce the electric bill simply by replacing the lamps in the high bay fixtures out in the warehouse. I already know what they're up to, they assume I'm running 400W MH fixtures and they're selling 250W MH PS conversion bulbs. Several problems here.

1) I'm already running TRUE 250W MH PS fixtures - the real ones - and could only benefit by going fluorescent.
2) Those conversion lamps, even though they work, have a terrible real world life expectancy record.
3) The "credits" they keep harping about was from years ago, changing to a more efficient MH system is no longer considered a valid method of increasing efficiency enough to qualify for any Federal or local power company incentives. Only fully changing over to a T-5 or T-8 fluorescent system now qualifies and half of my lighting demand is already handled by T-8 fixtures.

Yet salesmen will always be salesmen and by keeping two steps ahead of them can be fun. Last of them that claimed they could save me a fortune wanted to install PFC capacitors to increase my power factor percentage. They didn't do much research - our power company didn't penalize us unless we fell below 80% and I wasn't anywhere near that low at the time. (That # was upped to 85% last year) There were already PFC caps in the system - some hooked up, some not. By moving some around, taking a few offline, moving a few to different switch panels and adding 4 small ones directly across my main chiller contactors I'm running at a 98% PF. I think the saddest thing was that the salesmen they sent out didn't even really know what a 480V three phase system was, their specialty was pushing these on unsuspecting consumers who, in our state, aren't even monitored for power factor.

Ah well, after my fun I'll finish up installing the disconnect panel I added in one area that was lacking in regular 120V service, luckily there was an unused stepdown transformer already in the area that just needed 480 run to it.

 

If you have access to the attic and a helper with a flashlight it shouldn't be too hard to make that right again if you've got an illustrated book. Just go back a few feet, add a 4x4 junction box and splice in some new Romex. The book may just say to use wire nuts but you're always safer making connections inside a box. If any part of it confuses you just don't take any chances and call someone, probably an hour's worth of labor time at the most.

 

If the book says that, throw it out. Splices must ALWAYS be made in a listed box or raceway.

It looks like the wiring has already been wrapped with friction tape; that's a sure sign that the insulation is already heat damaged. Adding a junction box in the attic (it must remain accessible) or replacing that whole run is the only safe choice.
/mike

 

I bought a voltage detector just for this reason, 20 bucks at a Lowes (I could have found one cheaper but I needed it just then). It's a pen shaped device that's driven from an electrode attached to a mosfet gate that's biased in some way through a simple detector circuit, if you get it within a few inches of a live power line it'll start blinking and beeping at the line frequency (it goes batty when I put it within 6 inches of a small plasma globe) Even if the neutral is carrying current (bad house wiring) you can tell 'live' vs 'neutral' by the distance to the wire that the probe will activate at.

They won't show low voltage (low being less than like 50 volts) And I haven't done any experiments with DC other than I know it won't go off on contact with 12V DC.