Advisable To Recommend AFCI Breakers For Older Homes?

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Ravenvalor

Ravenvalor

Senior Member
Location
Piedmont region of NC
Hello,

I have a customer with a home built in the 30s that still has the original BX cable in it. Is it advisable to recommend that he replace the regular Siemens breakers with AFCI breakers where appropriate?

Thanks,
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Ravenvalor said:
Hello,

I have a customer with a home built in the 30s that still has the original BX cable in it. Is it advisable to recommend that he replace the regular Siemens breakers with AFCI breakers where appropriate?

Thanks,
Click to expand...
How would the cost delta between an AFCI breaker and a receptacle ever be appropriate from the customer's point of view?
 
P

paulengr

Senior Member
1. Are you prepared to hunt down all the false positive things that trigger the AFCIs?
2. NEC as written makes this a one way trip. If you put in the AFCI and it doesn’t work out you are stuck with it. Most likely you may find neutral or grounding issues forcing you to replace all the wiring.
3. Most BX is fine. Some isn’t but the damage is at the ends. You may have to tear open walls and redo the lathe and plaster or drywall it plus painting to replace the BX if the AFCI trips on it. Are you willing to all but gut the house to the frame and redo either the outside sheathing or inside sheathing?

In other words is HO willing to open this can of worms? We did it with my dads house but that was because it was balloon framing and the clapboard siding was rotting out. Once the siding came off the “insulation” had to be replaced anyway. At that point all the wiring was exposed from the outside so a total redo (replacing all the old 2 prong receptacles and old BX and paper insulated Romeo) was easy. But this is not a piecemeal job where you can poke along at it. I’d lean towards totally redoing it all or do the bare minimum.
 
Little Bill

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Most problems with the old BX was poor grounding/bonding. So if there was a short from hot to ground, hot to metal, the breaker/fuse would not trip/blow. That caused what is considered a glowing connection. That is a high resistance connection causing heat build up and eventually could cause a fire. The AFCI will not detect a glowing connection and has been proven. IMO, adding AFCI to an old house with BX wiring is just an unneeded expense and and false security. Also subject to false trippings due to crossed neutrals. I have a hard enough time installing AFCI (believing that they actually work) on new construction, so I would never add them when not required.
 
Ravenvalor

Ravenvalor

Senior Member
Location
Piedmont region of NC
Little Bill said:
Most problems with the old BX was poor grounding/bonding. So if there was a short from hot to ground, hot to metal, the breaker/fuse would not trip/blow. That caused what is considered a glowing connection. That is a high resistance connection causing heat build up and eventually could cause a fire. The AFCI will not detect a glowing connection and has been proven. IMO, adding AFCI to an old house with BX wiring is just an unneeded expense and and false security. Also subject to false trippings due to crossed neutrals. I have a hard enough time installing AFCI (believing that they actually work) on new construction, so I would never add them when not required.
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What if the old BX circuits were all coming from a subpanel which was being fed by a 60amp breaker. Could I replace that regular 60amp breaker with a Ground Fault breaker? Not a GFCI but a high Ma GF breaker? Most of the load is lighting.

Thanks for the valuable advise
 
L

letgomywago

Senior Member
Location
Washington state and Oregon coast
Occupation
residential electrician
Ravenvalor said:
What if the old BX circuits were all coming from a subpanel which was being fed by a 60amp breaker. Could I replace that regular 60amp breaker with a Ground Fault breaker? Not a GFCI but a high Ma GF breaker? Most of the load is lighting.

Thanks for the valuable advise
Click to expand...
That would trip if there are the issues anyway but it wouldn't add that total class A GFI safety.
 
Little Bill

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Ravenvalor said:
What if the old BX circuits were all coming from a subpanel which was being fed by a 60amp breaker. Could I replace that regular 60amp breaker with a Ground Fault breaker? Not a GFCI but a high Ma GF breaker? Most of the load is lighting.

Thanks for the valuable advise
Click to expand...
You might even have problems with a 2-pole GFCI breaker nuisance tripping due to the same (possible) crossed neutrals. Plus, you wouldn't want to lose several circuits if the GFCI tripped due to one faulty circuit. I would tend to add GFCI to each circuit before I would subject the whole panel to tripping.
 
Z

zbang

Senior Member
Location
Roughly 5346 miles from Earls Court
Before I'd consider installing AFCI's in a house like that, I'd megger the whole place to see what turns up, as well as check for bootleg grounds and the like. That's better spent money than just buying AFCIs and letting them do the testing.
 
Ravenvalor

Ravenvalor

Senior Member
Location
Piedmont region of NC
zbang said:
Before I'd consider installing AFCI's in a house like that, I'd megger the whole place to see what turns up, as well as check for bootleg grounds and the like. That's better spent money than just buying AFCIs and letting them do the testing.
Click to expand...
Would the megger serve the purpose of testing the insulation? Thanks… 👍
 
B

blueheels2

Senior Member
Location
Raleigh, NC
Occupation
Electrical contractor
I love my meter but they aren’t perfect. Only shows the insulation fault if there is some where for the voltage to bleed off or escape to. But still makes me feel better. Anytime I have a service call with lightning damage I break out the megger and test all of the circuits before energizing. Ive definitely found some issues with it

Had a service call a while back that the handyman couldn’t find the problem. I megged it out and found it within an hour.
 
Ravenvalor

Ravenvalor

Senior Member
Location
Piedmont region of NC
blueheels2 said:
I love my meter but they aren’t perfect. Only shows the insulation fault if there is some where for the voltage to bleed off or escape to. But still makes me feel better. Anytime I have a service call with lightning damage I break out the megger and test all of the circuits before energizing. Ive definitely found some issues with it

Had a service call a while back that the handyman couldn’t find the problem. I megged it out and found it within an hour.
Click to expand...
Have you ever used it on old BX Greenfield cable?
 
T

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
blueheels2 said:
I love my meter but they aren’t perfect. Only shows the insulation fault if there is some where for the voltage to bleed off or escape to. But still makes me feel better. Anytime I have a service call with lightning damage I break out the megger and test all of the circuits before energizing. Ive definitely found some issues with it

Had a service call a while back that the handyman couldn’t find the problem. I megged it out and found it within an hour.
Click to expand...
Yes, a megger is a handy tool but as you mention they have limitations for sure. Like old cracked insulation that is just sitting in free air will not be seen.
 
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