Why is the Romex in my 70's tract home so thick?

[NiceGuyEddie]

I'm doing some work and the existing Romex (brand name?) has very heavy gauge wires, they might be 10 gauge or even 8. Black sheathing, no markings.

The plethora of new stuff at the big box store is almost entirely 14 or 12 gauge, although there is one choice of 250ft of 10 gauge.

The existing wires are so thick, it's impossible to stick them straight into the back holes of the new outlets. It's a little challenging to curl the wires so they fit around the screw terminals, but do-able.

Why is this? I can think of three possibilites:


"They just don't make them like they used to." For example, I have a 1960's shop light that I converted to an extension cord, and the copper wires are THICK. In this case, they are stranded though.
Something to do with the copper itself - maybe it's not 100% copper and nowadays it's more pure, or a better alloy?
Something to do with the insulation? Meaning, the insulation years ago had to be "___" thick so the wires had to be thick?



Also, the ground wire of the older existing wires is significantly thinner, the new wires have all the gauges the same.

Just curious :confused:

[HerculezJT]

so there can be a lot of reasons for this, older homes typically had bigger gauge wiring because the components drew more amperage compared to now. Example: compare a 30" CRT TV to an LCD TV. CRT's are typically 140+ Watts, at 120V = over 1A. LCDs are 30-50Watts, so amperages is around .3A. Now 1A doesn't make a difference alone on the circuit, but when you have Lamps, and vacuum cleaner and the old vacuum tube radios, amperage climbs up. which requires large gauge wiring.

[Al_C]

Do you know what the building code requires/required in your area? That could answer a lot of your questions. Also consider that where the circuit is destined also determines the size of wire, i.e. a kitchen circuit might be a 12 wire where a dining room might be a 14...

I'm not a home builder or electrician, but these are my thoughts on the topic. Ask Steno. He's wired a bazillion homes. He'll know.

[NiceGuyEddie]

I have worked in all areas of the house and the wires are uge all around.

I'm not sure if it's related to the wiring, but I do know my home was constructed under early California Title 24 energy standards for residential homes. I recently learned one of these items were the maximum amount of windows and window area you can have according to the size of the home. This was of course before double-pane insulated windows - the house came with single-pane aluminum frame windows (sucked.) It came with popcorn ceilings (added to R-value) and blown insulation in crawl spaces in addition to the roll insulation.

It makes sense that things in the past drew more power. The house came with original outdoor flood lighting which likely had up to (2) 100W spot lights each. There are three per home with my model - garage, side, and back. We know they are original because all the un-upgraded or restored homes still have the same flood lights.

Sometimes when curling the wire ends to go over the screws on the new outlets, the wires break. Kinda scares me, it's almost as if they are "dry."

What's odd is the existing ground wire in the Romex is WAY thinner than the other two wires.

[mike223]

Also, the ground wire of the older existing wires is significantly thinner, the new wires have all the gauges the same.

Just curious :confused:

The copper is the same, the theory on the ground wire changed.

In the 1950s they were typically wiring outlets without a ground - which was getting people electrocuted occasionally in the kitchen or bath (2 prong outlet).

In the 1960s they started running a ground wire that was just big enough to trip the breaker in the event of a ground fault.

Mid 1970s early 1980s they went to a full size ground.

Mid 1980s started running GFCI breakers for kitchen, garages and baths.

Mid 1990s worked GFCI into outlets.



The different wire sizes are for different loads - typically not to exceed 15 amp breaker for #14, not to exceed 20 amp breaker for #12, 30 amps for #10, 50 amps for #8.

The breakers are sized to protect the wire - to trip the breaker before there's any chance of overloading the wire size (and thereby burning the house down).


So don't try splicing #14 wire (15 amp) into a #12 circuit (20 amp) - you'll burn the house down before the breaker will trip.


At some point (mid 1990s?) they started color coding the romex sheath so the inspector could see at a glance if you had screwed up (like using #14 somewhere in a 20 amp run, or #12 in a 30 amp run, etc).

[mike223]

Sometimes when curling the wire ends to go over the screws on the new outlets, the wires break. Kinda scares me, it's almost as if they are "dry."



Copper work hardens quickly - such as if it's been bent around a terminal, straightened out, and bent around another terminal - it may break on you.

I always try to leave a little extra so the next guy can just cut it off and start fresh.

[mike223]

Further clarification.

I would have edited it into an earlier message, but I didn't want to take a chance that Eddie would miss it.


If you don't have any 15 amp breakers you absolutely should not be running any #14 romex.


Also, a lot of the 115v outlets they're selling at the big box stores are 15A outlets (and therefore intended for #14 wire, 15A breakers).

You generally pay extra for the 20A outlets (which your 1970s tract home was probably wired with in the first place, along with 20A breakers + #12 romex).

[NiceGuyEddie]

I just checked and I have all 15A breakers plus a single 40A breaker for the stove (which oddly is 120V and isn't electric) and a double 40A breaker for the HVAC.

Everything I've ever done is "end of run" - for example adding an extra outlet and I've always used the 12ga.

I added an end-of run box & switch for an exhaust fan for the garage. The fan is ~2A / ~250W and I could not believe how thin the wires were - super thin and stranded.

Sorry to say I didn't understand: If you don't have any 15 amp breakers you absolutely should not be running any #14 romex.

[mike223]

Sounds like you're Ok.

I'm a little surprised they ran #12 wire with 15A breakers.

My comment on #14 romex was based on a (incorrect) theory that maybe you were adding #14 on the end of #12 runs.


Just a theory I came up with because you were talking about the larger wire sizes (and maybe you were just talking about the small ground wires).

[Jeff Kleiner]

It's not aluminum wire is it? It was used from the mid sixties through late seventies, usually in lower end houses, when copper prices were high. It was outlawed around 1976-78 or thereabouts. I haven't come across any for years but if memory serves the diameter of an aluminum wire was slightly greater than the diameter of the same (rated) gauge copper.

Jeff

[mike223]

It's not aluminum wire is it? It was used from the mid sixties through late seventies, usually in lower end houses, when copper prices were high. It was outlawed around 1976-78 or thereabouts. I haven't come across any for years but if memory serves the diameter of an aluminum wire was slightly greater than the diameter of the same (rated) gauge copper.

Jeff


Nice catch - I'd forgotten about that, and I've never found any inside a house.

I have seen it used from the transformer to the meter - but I had completely forgotten the 1970s aluminum wire uproar.


I think you're supposed to use two wires sizes larger???


And it work hardens faster than copper...


And that would explain why they ran bigger than #14 on 15A breakers...

[NiceGuyEddie]

The sister tract across the "semi-main road" are homes that were built about 1 year later and they have aluminum wire so I'm sure mine are copper. Those homes also have galvanized plumbing, mine is copper. They also have (had) asphalt driveways and my tract has all concrete.

[GWL]

While working on our 1908 cottage in Vermont which had been redone a bit in the '70's by the previous owner. Most of the wire he used was the standard 14 gauge but the insulation was much thicker than todays wire. I'm guessing the insulation is now better and thus can be thinner.

I know there are different levels of automotive wiring with different insulation. The better insulated wires, which will not burn alone on its own, actually have thinner insulation. The standard stuff you get at the auto stores have thicker insulation but will usually sustain a flame on its own. I bought a bunch of the better wire from the Wire Barn and used it on my build. They sell different levels of wire and you can get more information from them.

George

[Bronco Mike]

Probably copper clad aluminum wire, it was commonly used during the 70s in California. It’s a nightmare, breaks easily and is a fire hazard. I have it in two rental properties. I just deal with it because the cost to rewire is crazy expensive.

[mike223]

I did a little research on it later last night.

One of the home inspection sites said that 15 amp breakers with 12 gauge wire are a dead giveaway - due diligence for an inspector is to go looking for aluminum wire based on that alone.