old bx cable

[rob12013]

Hello
The armored cable without a ground wire maybe from the 1940s
is that 16 gage wire? I here it's grandfathered but most likely on new 15 amp breakers with half house refurbishes. Could someone please tell me the ratings of the old armored cables from the 40s?
Thanks

 

[Volta]

Hello
The armored cable without a ground wire maybe from the 1940s
is that 16 gage wire? I here it's grandfathered but most likely on new 15 amp breakers with half house refurbishes. Could someone please tell me the ratings of the old armored cables from the 40s?
Thanks

Until 1959, it may have been a 16 or 18 awg al, or 20 cu, if there at all. As of 1959 the bonding strip was required. 1959:334-2(b)

Some tests done in 2007 to old AC showed that the insulation samples all passed a 5000 volt test, but the resistance of the sheath tended to be high, maybe over 3 ohms per 100 feet, I think.

 

[Volta]

Hello
The armored cable without a ground wire maybe from the 1940s
is that 16 gage wire? I here it's grandfathered but most likely on new 15 amp breakers with half house refurbishes. Could someone please tell me the ratings of the old armored cables from the 40s?
Thanks

Oh, do you mean the current carrying conductors?
In 1940 the allowable curent-carrying capacity of 16 awg was 7 amperes (except for heater cables[cause- or effect:roll:]) 1940: Chapter 10, Note 1.

Type AC cables' conductors were to comply with the requirements for rubber-covered conductors. 93341a.

IMO, that would fall under the 50 deg C row of the Conductor Insulation table. If smaller than #14 it would not be listed in the Allowable Current-Carrying Capacity table and could not be used for light and power wiring.

 

[rob12013]

This is 16 awg been there sence the 40s it looks like
10 awg untill I use my strippers at 16 and no dammage
to the wire. Seems like it went in after knob and tube on
this street. The joints were sodered. I'm glad it's on arc falts

 

[al hildenbrand]

Armored cable (BX), by the 1940s was already a old wiring method. It was developed decades earlier.

The armor of that old cable was already well established as a grounding means. Some of the code citations are available if you click on this thread link. Note that the armor had to be solidly connected as part of a continuous path . . .

It was a popular product, when used with existing K&T installations, because you could easily fish it, and add a new switch, receptacle or light. For an K&T extension, the armor did not have to be bonded to the EGC, and the physical protection of the armor made the labor of installation simpler, compared to fished K&T.

I have found that some unbonded BX armor can "look" like its grounded if it lays over old metallic gas and/or plumbing piping. A simple continuity test may not be enough to verify an existing ground on the BX.

Rob12013, you report the insulated BX conductors are #16 gage. I've never seen that.