Cinder block apartment rehab

[Jason Blasenak]

Hey all,

I am considering buying a multi unit 1950's constructed cinder block apartment building and wanted some advise.  The electric is knob and tube which is the major problem with cinder block walls.  The second issue is how to update the unit to place CAT6 lines.  Any help in this area would be greatly appreciated.  I have a fantastic GC to run the project but don't want to estimate too low on rehab costs and sink my profitability from the beginning.

[Matt R.]

Disclaimer: I am not a professional electrician.

1950s sounds kind of late for knob and tube wiring; I associate that more with the 1930s and before.  By the 1950s, it was probably most common to use conduit, flexible armored cable (BX), or maybe the early versions of nonmetallic cable (Romex).  Are you sure you don't have conduit instead?  Knob and tube looks like this, flexible armored cable looks like this, and conduit looks like this.

If it's BX, and it needs to come out for some reason, about the only thing you can do is pull the whole wire and replace it with modern armored cable; you can't easily put new wires in the old metal armor.  You may be able to use the old cable to pull in the new, so don't just wildly rip out all the old cable first.  When you do get the old cable out, the whole pile may be worth a few bucks at your local scrapyard.

If it's really conduit wiring, the things I would look for would be rubber-covered wiring, and maybe rusty conduit.  For a while, the insulation on individual wires was rubber, which tends to dry out and come off over the decades.  Modern wire has plastic insulation, which doesn't go bad.  The nice thing about conduit is that it's relatively easy to pull the old wires out and pull in some new ones.  One thing to watch for - under older electrical codes, the conduit itself was allowed to serve as the ground wire, but now you're usually required to run a ground wire inside the conduit.  If you have to do this, some of the conduit might be too small to handle the extra wire.  Your local building inspector (city/county) will be able to advise.

A little surface rust isn't bad, but if the conduit has rusted through, you'll need to replace it.  If the rusty spot is relatively close to a box, this isn't too bad, but if there's one rusty spot in the middle of a run, it can be a pain in the butt.

For the Cat6 outlets, you'll probably have to use electrical boxes that mount on the surface of the walls.  You can get plastic or metal ones, and both kinds can be painted to match.

You *might* be able to drill a hole into the cinder block where you want the outlet, and another hole above that one at the top of the wall, and fish the cable through the holes in the blocks inside the wall.  If that doesn't work, you can use conduit mounted on the surface of the wall.  Regular conduit (the same stuff you'd use for 120 V) works fine, but for Cat6, you can also use flat plastic "conduit" - Wiremold, among other people, makes this.  If you can run the flat plastic stuff in the corner, along the baseboard, etc, and paint it to match the walls, it doesn't look too bad.

Sometimes holes for pipes are a good place to sneak an Ethernet wire through.  You want to stay away from things like the flue pipe for a furnace or dryer, but holes for the water or sewer pipes work fine.  Then you just have to explain to the tenants why the Ethernet jack is under the kitchen sink or in the bathroom.  :)

[Jason Blasenak]

Thanks Matt!  That is very helpful.  After re examining the property, the fuses are the typical knob and tube but they have placed conduit in the apartments.  The outlets are not grounded.  

I doubt the tenants would like their ethernet jacks near the sink ;)

[Josh Rowley]

Ethernet cables? I have several of these buildings and the tenants just use wifi. If it were me I wouldn't worry about cabling.

[Matt R.]

Originally posted by @Jason Blasenak:

After re examining the property, the fuses are the typical knob and tube but they have placed conduit in the apartments.  The outlets are not grounded.

You have "plug" or "Edison base" fuses - the ones that screw in just like a light bulb.  If you buy the property, at least make sure that there are spare fuses on site - like, sitting on top of the fuse box.  Alternatively, you can get 15 A and 20 A circuit breakers that screw in where a regular fuse would go.  Also, unscrew each fuse, one at a time, and check for pennies or washers behind it... people really did do that and it really does start fires.

You might consider replacing the fuse box with a modern breaker panel.  On the good side, you may get a discount on your insurance for this - ask your agent or broker.  On the bad side, you may be required to bring everything else electrical up to code at the same time, which means running more circuits.  You may also be required to hire an electrician for replacing the panel, rather than DIY.  Your city/county code inspector will be able to tell you what is required in that jurisdiction.

The conduit is *probably* grounded, even if the receptacles only have 2 holes.  If you can prove that the conduit is grounded, it used to be OK to just install 3-hole receptacles and let the conduit serve as the ground.  This is no longer accepted for new builds, but might be OK on a retrofit - again, local code inspector is the person who would know.

[Matt R.]

Originally posted by @Josh Rowley:

I have several of these buildings and the tenants just use wifi.

Jason may be anticipating the availability of gigabit Internet service, which is faster than any available wi-fi... running cables is the only way to get the full speed.  Google Fiber is one well-known provider; AT&T is claiming they will offer it in some cities where they paid off the city councils to keep Google out.  Some areas here in Kansas City have Google Fiber, and if a building has it, landlords always mention it in the ad... it's a good selling point.

Even without gigabit Internet, you will *always* get better speeds from a cable than you do from wi-fi.  For many things you won't notice the difference, but for some things (like streaming HD video) the difference is noticeable.