AFCI Breakers

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kwired said:
Do they use anything in regular construction lumber for treatment? There is treated lumber but it is not normlly used for general construction in locations expected to remain dry. Maybe a sill plate on a concrete foundation at times but the rest of the wall will be non treated.
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For that you would need to look here, it?s a free download:

http://www.planningportal.gov.uk/buildingregulations/approveddocuments/downloads

The industries I?ve worked in most of the above didn?t apply. Testing did.
 
iwire said:
May show.

You could have damaged insulation that you won't pick up and never cause a problem in use.
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If the fault doesn?t show at 2xUo it?s hardly likely to show at Uo unless you?ve got the hippopotamuses from WD Fantasia dancing on the floor above.




Just to add;
I use an old established calculation for minimum acceptable IR based on maximum permitted leakage current for circuits and motors.
The IET dropped it from BS7671 because it isn?t a ?one size fits all? figure. They wanted something simple for people to follow.
The calculation has got my backside out of the fire many times when modifying old plant. Replacing cables that didn?t fit the ?one size fits all? figure would have cost ?X00K.
Some of the cables are now getting onto 75 years old, the extra load I chucked at them improved the IR readings. They get tested every 12 months under the UK?s M&Q regulations (which are a statutory requirement.)
Although the calculation isn?t in BS7671 it would hold up in any court of law due to it being based on accepted facts and figures.

Funny old world isn?t it?
 
kwired said:
Do they use anything in regular construction lumber for treatment? There is treated lumber but it is not normlly used for general construction in locations expected to remain dry. Maybe a sill plate on a concrete foundation at times but the rest of the wall will be non treated.
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To honest I don't know (engineered trusses do), but I know when you under go linemen training they teach you that all wood has some moisture in it, enough so that at 7.2kv or 13.2kv it will conduct power to seriously shock or even kill. Ohms law would mean much less at 120 volts, but this is possible in theory:


http://www.mikeholt.com/htmlnews/grounding/un250-66.jpg
 
Tony S said:
If the fault doesn?t show at 2xUo it?s hardly likely to show at Uo unless you?ve got the hippopotamuses from WD Fantasia dancing on the floor above.




Just to add;
I use an old established calculation for minimum acceptable IR based on maximum permitted leakage current for circuits and motors.
The IET dropped it from BS7671 because it isn?t a ?one size fits all? figure. They wanted something simple for people to follow.
The calculation has got my backside out of the fire many times when modifying old plant. Replacing cables that didn?t fit the ?one size fits all? figure would have cost ?X00K.
Some of the cables are now getting onto 75 years old, the extra load I chucked at them improved the IR readings. They get tested every 12 months under the UK?s M&Q regulations (which are a statutory requirement.)
Although the calculation isn?t in BS7671 it would hold up in any court of law due to it being based on accepted facts and figures.

Funny old world isn?t it?
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What does a typical ring final, or radial 2.5mm2 twin and earth usually read?
 
mbrooke said:
What does a typical ring final, or radial 2.5mm2 twin and earth usually read?
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New as anyone would expect >50M ohm or on my meter >100M ohm @2xUo. The number of times people bemoan low readings is amazing, neon?s are the usual culprit.

Heavy power and plant control is my field not domestic, one house every eight years is more than enough for me.

But no matter, testing still has to be done.

300m of 0.3?? PILC I would take the calculated minimum based on the OCPD.
One big mistake many make with long cables is just pressing the test button and getting low readings, keep your finger on the button and as the cable charges the reading rises.

The bigger (expensive) Megger?s have a time/hold function. A standard test would be five minutes unless 50G ohm was reached within one minute. Even the weather conditions were recorded on the test sheet, it makes a big difference above 1KV. (I wrote our company standard for this test)
Our meter would go to 100T ohm @5KV Pity I couldn?t take it with me when I retired.


Why can?t an engineering site accept mathematical symbols?
 
Tony S said:
New as anyone would expect >50M ohm or on my meter >100M ohm @2xUo. The number of times people bemoan low readings is amazing, neon?s are the usual culprit.

Heavy power and plant control is my field not domestic, one house every eight years is more than enough for me.

But no matter, testing still has to be done.

300m of 0.3?? PILC I would take the calculated minimum based on the OCPD.
One big mistake many make with long cables is just pressing the test button and getting low readings, keep your finger on the button and as the cable charges the reading rises.

The bigger (expensive) Megger?s have a time/hold function. A standard test would be five minutes unless 50G ohm was reached within one minute. Even the weather conditions were recorded on the test sheet, it makes a big difference above 1KV. (I wrote our company standard for this test)
Our meter would go to 100T ohm @5KV Pity I couldn?t take it with me when I retired.


Why can?t an engineering site accept mathematical symbols?
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Ok, thanks, that makes more sense. My apologies for bothering you with domestic.

Good point on charging, a person needs to hold the button to charge the cable, and then the reading hold. Don't forget to discharge the cable either, Ive learned that the hard way :lol: And yes, weather can affect readings. Generally higher humidity results in lower readings?
 
mbrooke said:
Ok, thanks, that makes more sense. My apologies for bothering you with domestic.

Good point on charging, a person needs to hold the button to charge the cable, and then the reading hold. Don't forget to discharge the cable either, Ive learned that the hard way :lol: And yes, weather can affect readings. Generally higher humidity results in lower readings?
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Join the club, it HURTS!
It was hilarious when an interfering manager climbed between ?danger electrical test area? barriers.
I was sat in the substation watching the IR/time reading, the reading suddenly dropped and there was a squeal from outside. Pity it was only on 2.5KV to earth. I had to redo the test!
 
Tony S said:
Join the club, it HURTS!
It was hilarious when an interfering manager climbed between ?danger electrical test area? barriers.
I was sat in the substation watching the IR/time reading, the reading suddenly dropped and there was a squeal from outside. Pity it was only on 2.5KV to earth. I had to redo the test!
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:eek: I bet he learned that one quick :lol:
 
My 2 cents on this issue. AFCI's are a solution to a problem that doesn't exist. Despite its flaws, our North American power systems do not need AFCI's. I would also argue that we do not need European style current differential devices either for every circuit in a dwelling unit. I agree that a high threshold RCD/GFCI is far more valuable and reliable than an AFCI but I question the need for it. We certainly should not adopt a UK style RCD main breaker type of setup that could potentially put an entire house in the dark, hence why we use individual branch circuit GFCI/AFCI protection.

That being said, I do support some UK-style testing for our branch circuits but not to the extent that British electricians are required. A simple L-N and N-G continuity test would locate most faults and insulation testing would find even more. But mandating that level of testing is highly unlikely even though it is far more logical and worthwhile than AFCI's.

Bottom line, there was nothing so badly broken about our electrical systems that required such drastic changes to the NEC that just so happen to heavily favor an unproven, worthless technology called the AFCI. We were find before the AFCI existed. Anyone who blindly supports AFCI's based on junk statistics from manufacturers and consumer safety groups is a huckster at best.
 
MasterTheNEC said:
Everyone makes mistakes Don......People are not perfect but they tend to have good intentions.
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Wow, just wow.

First off, the manufacturers flat out lied to the CMP about AFCI's. Secondly, a manufacturer does not have "good intentions" when it comes to their influence on CMP's. They have one and only one goal - profit. Pushing their products into mandatory use increases their profit. There is absolutely nothing benevolent whatsoever about having manufacturers representatives on CMP's.
 
peter d said:
My 2 cents on this issue. AFCI's are a solution to a problem that doesn't exist. Despite its flaws, our North American power systems do not need AFCI's. I would also argue that we do not need European style current differential devices either for every circuit in a dwelling unit. I agree that a high threshold RCD/GFCI is far more valuable and reliable than an AFCI but I question the need for it. We certainly should not adopt a UK style RCD main breaker type of setup that could potentially put an entire house in the dark, hence why we use individual branch circuit GFCI/AFCI protection.

That being said, I do support some UK-style testing for our branch circuits but not to the extent that British electricians are required. A simple L-N and N-G continuity test would locate most faults and insulation testing would find even more. But mandating that level of testing is highly unlikely even though it is far more logical and worthwhile than AFCI's.

Bottom line, there was nothing so badly broken about our electrical systems that required such drastic changes to the NEC that just so happen to heavily favor an unproven, worthless technology called the AFCI. We were find before the AFCI existed. Anyone who blindly supports AFCI's based on junk statistics from manufacturers and consumer safety groups is a huckster at best.
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Very true.

Nice to see you back.
 
peter d said:
Wow, just wow.

First off, the manufacturers flat out lied to the CMP about AFCI's. Secondly, a manufacturer does not have "good intentions" when it comes to their influence on CMP's. They have one and only one goal - profit. Pushing their products into mandatory use increases their profit. There is absolutely nothing benevolent whatsoever about having manufacturers representatives on CMP's.
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I would agree, and they should never have anyone in a voting capacity when it comes to their bottom line.
 
peter d said:
My 2 cents on this issue. AFCI's are a solution to a problem that doesn't exist. Despite its flaws, our North American power systems do not need AFCI's. I would also argue that we do not need European style current differential devices either for every circuit in a dwelling unit. I agree that a high threshold RCD/GFCI is far more valuable and reliable than an AFCI but I question the need for it. We certainly should not adopt a UK style RCD main breaker type of setup that could potentially put an entire house in the dark, hence why we use individual branch circuit GFCI/AFCI protection.

That being said, I do support some UK-style testing for our branch circuits but not to the extent that British electricians are required. A simple L-N and N-G continuity test would locate most faults and insulation testing would find even more. But mandating that level of testing is highly unlikely even though it is far more logical and worthwhile than AFCI's.

Bottom line, there was nothing so badly broken about our electrical systems that required such drastic changes to the NEC that just so happen to heavily favor an unproven, worthless technology called the AFCI. We were find before the AFCI existed. Anyone who blindly supports AFCI's based on junk statistics from manufacturers and consumer safety groups is a huckster at best.
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Best reply ever regarding AFCIs :D:)


If this forum had a like button with unlimited likes I would hit it at least 1000 times. :thumbsup:
 
bphgravity said:
So just out of curiosity, which other voting group do you think this statement doesn't apply to?

U?
I/M?
L?
AR/TL?
E?
I?
C?
SE?
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A manufacture has no place on a board that votes laws that can benefit them financially.

I do not know about the rest of the country but here in Calif. a person cannot sit on a board that makes code or law or legislation where that individual has a financial benefit.
It's called the Brown Act. That is my understanding.
 
Most of the groups have some economic interest in the code rules, but the manufacturers the testing labs have the most to gain when new products are required by the code. I would put them in the following order as far as economic interest with the first two having more economic interest that all of the rest combined.


  1. Manufacturer (M): A representative of a maker or marketer of a product, assembly, or system, or portion thereof, that is affected by the standard.
  2. Applied Research/Testing Laboratory: A representative of an independent testing laboratory or independent applied research organization that promulgates and/or enforces standards.
  3. Installer/Maintainer (I/M): A representative of an entity that is in the business of installing or maintaining a product, assembly, or system affected by the standard.
  4. Consumer (C): A person who is or represents the ultimate purchaser of a product, system, or service affected by the standard, but who is not included in (2).
  5. Insurance (I): A representative of an insurance company, broker, agent, bureau, or inspection agency
  6. User (U): A representative of an entity that is subject to the provisions of the standard or that voluntarily uses the standard
  7. Labor (L): A labor representative or employee concerned with safety in the workplace.
  8. Enforcing Authority (E): A representative of an agency or an organization that promulgates and/or enforces standards.
  9. Special Expert (SE): A person not representing (1) through (8), and who has special expertise in the scope of the standard or portion thereof.
 
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