Loop Impedance Test

[romex jockey]

Ever hear of Herb Ufer or Eunice Soares User?

Guess what they were doing when the queen was trying to figure which end of the crumpet faced up....

~RJ~

 

[mbrooke]

A lofty aspiration to actually assume the level of manufactured home wiring methods MBrooke....

I'd certainly need more theory class.....

~RJ~

IMO it gets the job done :thumbsup:

Lord i need a tall one before we go there MBrooke...~RJ~

Sit right back and relax :thumbsup:

 

[mbrooke]

Nope-just not quite as common as many believe and not quite as dangerous as many believe-not that many people meet their demise at the hands of a n>g fault and I have seen some soldered (yes, soldered) neutrals that had been incorrectly tied together decades ago and are still trouble free.
Both of these practices are indeed potentially dangerous, fires do happen as a result, but most of the time these will go unnoticed and are largely inconsequential.

Inductive heating, power quality, voltage gradients, EMF, shock hazards...

Anyone with real world experience will tell you conduit heats up when the net current isnt zero.

 

[Tony S]

I’ve been out of action for a couple of days due to illness and so missed the start of this thread.

I set to clicking on multiple quotes until I realised I would be writing a book that would equal BS7671 and the NEC in one post.


DrSparks,
You say if loop testing is done it needs to be witnessed by an inspector.
I’ll offer this argument, if you had a recognised testing procedure you wouldn’t need inspectors. We have a set format of tests to follow which are forwarded to BC (building control, your AHJ). They are legally entitled to drop on any job and verify the submitted results, the electrician won’t even know. Until afterwards!


GFCI (RCD) testing, you bought a smile to my face with you’re testing method, two wires and a pair of pliers. Are you serious, that isn’t testing by any stretch of the imagination. You don’t know any facts to determine the unit is working within specification.
The RCD RCBO’s are live tested at the following levels of the rated tripping currents on both 0 and 180 deg of the AC wave form.
0.5 the device should not trip
1.0 the device should trip within the specified time
5.0 the device should trip within the specified time
Ramp test where the leakage current is gradually increased the find the tripping threshold. Again this should be within the set limits specified by the regulations not the manufacturer.


Circuit loop impedance testing. High impedance can hold a fault current below the OCPD trip threshold. Faulty connections are getting hot as well as the point of fault.


Live loop impedance (impulse) testing at the point of supply. This has the added bonus of giving the maximum prospective fault current for both line to line, line to neutral and line to earth (ground) ensuring the protection devices are capable of breaking the fault.

I can’t say it was fun being called to a panel, standing there and thinking “I wonder what that used to be?”
A heavy fault near the panel had caused the 50A MCB to trip, it wasn’t rated to the fault level and exploded taking the most of the panel out. Nothing was worth salvaging, the cabling required major repairs.
All through someone not checking the maximum prospective fault current.


No matter what country you’re in, bind faith in codes/regulations is no substitute for substantiated fact.


BTW,
We have just the same problems with “have a go Joe”. Nothing will stop him burning down his own home.

 

[user 100]

Inductive heating, power quality, voltage gradients, EMF, shock hazards...

Anyone with real world experience will tell you conduit heats up when the net current isnt zero.

Never said they weren't dangerous-your making assumptions. They are dangerous, but they are not leading to millions of homes burning to the ground every year and thousands of electrocutions every year. You can try to spin it anyway you want, but ELIT testing millions of existing installs isn't going to be beneficial.

 

[romex jockey]

A heavy fault near the panel had caused the 50A MCB to trip, it wasn’t rated to the fault level and exploded taking the most of the panel out. Nothing was worth salvaging, the cabling required major repairs.
All through someone not checking the maximum prospective fault current.


No matter what country you’re in, bind faith in codes/regulations is no substitute for substantiated fact.

.

Try 480@ 250A blinding you temporarily

if i seem to opine hard here, it's because i learn hard too

~RJ~

 

[mbrooke]

Don't feel bad that America didn't adopt ELIT first? This test is used around the world .
That' a lot of savy smart electricians. I have article that support my opinions on this subject.
Copy righted materials by others. Sorry forum rules ....not permitted to post.
There's volumes written on the subject. Just go on the World Wide Web for all the support and help

I believe you. Most codes around the globe require it. The IEC even has an entire section dedicated to it (IEC 60364-6-61)

Maybe the rest of the world could teach us a thing or two??? Since we are now a global economy

The world can learn from us and we can learn from them. To condemn either without investigation stifles progress. I have learned a lot from studying foreign codes and the history of our own NEC.

The ElIt is not currently available in the USA since some feel it's a waist of time and money.

Unfortunately some do not like tradition challenged. Ironically some of the very code requirements (like GFCIs, wire sizes) are driven by the lack of assurance in electrical installations.

 

[mbrooke]

Never said they weren't dangerous-your making assumptions. They are dangerous, but they are not leading to millions of homes burning to the ground every year and thousands of electrocutions every year. You can try to spin it anyway you want, but ELIT testing millions of existing installs isn't going to be beneficial.

Ok, my mistake. My apologies :ashamed1: You are correct they arent burning down millions of homes, and with NM their really is no inductive heating concern, however does that mean a known code violation ought to be tolerated? In some cases it can lead to fire and shock.


As for EFLI (different from insulation resistance), there is no way of knowing the EGC is intact. GFCIs are becoming the back up EGC. The 2017 code is said to require them now on 15 and 20amp 240 volt circuits along with special ground fault protection in other cases. If that requirement extends to hard wired equipment EFLI can certainly be used to bypass that requirement from a theoretical standpoint.

 

[iwire]

Whenever I have proposed or mentioned something on this forum that is being done regularly with success but other members are unaware; I am automatically met with 'it will never work', 'it only looks good on paper' 'your nuts' 'no one would ever do that its dangerous'

Let's stop for a minute and think about what you are saying.

• You can question the ethics of the CMP members
• You can disparage electricians
• You can make unsubstantiated claims about manufacturers

But when we don't simply accept your opinions as facts it is us who is in the wrong.

I think I have finally met someone with a bigger ego than myself.

However reality is proving most those statements wrong and I knew that ahead of time.

Uh huh. :happyno:

What I take away is that questioning tradition will be met with strong opposition regardless of being wrong or right. This is perhaps why we are falling behind when compared to the rest of the world, because any new theory or knowledge is automatically discredited simply for being different then established traditions.

Show the need for it first, than people will be behind it. But so far all you have provided is 'This is how it should be, by the word of mbrooke'

Sorry as sure as you are that you have all the answers many of us need more than that before getting behind a change that will add cost and labor.

 

[peter d]

I will never sign any kind of paper certifying an electrical installation I have done. Why, you ask?

Some handy hack may come along and modify what I did, causing a hazard. Not my fault and not my problem.

Some hack electrician may come along and modify what I did, causing a hazard. Not my fault and not my problem.

Some homeowner may come along and modify what I did, causing a hazard. Not my fault and not my problem.

Pretty much anyone may come along and modify what I did, causing a hazard. Not my fault and not my problem.

 

[peter d]

Except maybe the requirement to use AFCIs???

Of course. Our system was not so broken as to require AFCI's in the first place.

Nor do we need:

-Insulation testing
-Ground loop impedance testing
-Whole house GFP
-Gimmicky devices that detect heating at splices and wiring devices

We have a good, safe and reliable system that has worked for a long time now. The trouble starts when people invent and legislate products that are a solution to a problem that doesn't exist.

 

[peter d]

I think I have finally met someone with a bigger ego than myself.

Did you ever have that airplane hangar door installed on your house so you can get your head through it? :lol:

 

[user 100]

Ok, my mistake. My apologies :ashamed1: You are correct they arent burning down millions of homes, and with NM their really is no inductive heating concern, however does that mean a known code violation ought to be tolerated? In some cases it can lead to fire and shock.

Yep, your mistake and no a code violation shouldn't be tolerated. What rubs me the wrong way about this kind of stuff is when there is generosity w/ respect to actual risk-a relatively small risk quickly becomes a raging epidemic that requires much expense to mitigate. As for your remark about real world experience, I've been bit by an incorrectly shared neutral before, but that doesn't mean that a large part of the US housing stock is problematic and requires billions of dollars in unnecessary testing.

I will say this-if someone wants to pay for these tests of their wiring, I see no reason why we couldn't give it to them, but it shouldn't be mandated.

 

[iwire]

Did you ever have that airplane hangar door installed on your house so you can get your head through it? :lol:

No, the town said I was not zoned for it.

I just grease my ears and push my way in.

 

[mbrooke]

Let's stop for a minute and think about what you are saying.

• You can question the ethics of the CMP members
• You can disparage electricians
• You can make unsubstantiated claims about manufacturers

I do not believe I am disparaging electricians, certainly not my intent. If I was I wouldn't be trying to find a way to increase their worth which they already have tons of. This is a respectable trade.

I do believe the trade can be improved, and I do believe the CMPs are being lobbied against to pass gimmicks based on problems some of which do not even exist.

But when we don't simply accept your opinions as facts it is us who is in the wrong.

You continue the claim all my facts are opinions. I have proof the back them up, but you refuse to accept it. When Tony brought up RCDs you fled because you knew he would discredit your statement regarding nuisance tripping. Ditto when I posted docs to back up my statement magnetic trip provides arc fault protection from an NRTL standpoint.

I think I have finally met someone with a bigger ego than myself.

I do see a lot of ego driven behavior on your part, however assuming so on my part is a mistake as that is not my intent. I am not driven by ego, I am driven by the beauty I see in our trade which imo is an art. My intent is to improve the code and the trade. Doing so requires questions, data, and debating electrical theory.

Uh huh. :happyno:

Do I need to go back and quote how many times someone has said X will never work only to then post documentation proving it does?

Show the need for it first, than people will be behind it. But so far all you have provided is 'This is how it should be, by the word of mbrooke'

As I said, the statistics of tripping GFP and open EGC are out there.

Sorry as sure as you are that you have all the answers many of us need more than that before getting behind a change that will add cost and labor.

Not answers at this point, but concepts worth exploring in further detail. Some of them have been deployed over seas and have so far been proven to be a success. Keep in mind what has made the US and other countries successful is taking into consideration what has worked for others. Its said Walt Disney was inspired by Tivoli Gardens in Denmark to great Disney Land, Pizza came from Italy and when it comes to the US, China has everything to thank us for technology, and the rest of the world has computers thanks to our Silicon valley.
[h=1][/h]

 

[Tony S]

I’ve just been given a book “Arcs Sparks and Engineers” detailing the history of a UK switchgear manufacturer A Reyrolle from 1901 to 2001.

It goes in to their successes and the failures.

Protection systems have developed over the years, some like the AFCI have turned in to blind alleys. They had the courage to admit their failings.

Will today’s manufacturers have that courage?



The book was presented by a former apprentice of mine.

 

[mbrooke]

I’ve just been given a book “Arcs Sparks and Engineers” detailing the history of a UK switchgear manufacturer A Reyrolle from 1901 to 2001.

It goes in to their successes and the failures.

Protection systems have developed over the years, some like the AFCI have turned in to blind alleys. They had the courage to admit their failings.

Will today’s manufacturers have that courage?



The book was presented by a former apprentice of mine.

Any links by chance? Sounds interesting

 

[sparks1]

Perhaps the whole inspection process should be reviewed since most
new residential circuits are not tested under any load conditions to look for high impedance.High impedance
Could also be introduced as a result of voltage drop if the branch circuit runs are too long. Voltage drop under load is another reason why the AHJ should consider and have the electrician rule before signing off.
This would also provide proof that the electrical workmanship is
code complience for the builder their customers.
.. Elit could be made part of fire prevention regulations to obtain an occupancy permit.

 

[mbrooke]

Perhaps the whole inspection process should be reviewed since most
new residential circuits are not tested under any load conditions to look for high impedance.High impedance
Could also be introduced as a result of voltage drop if the branch circuit runs are too long. Voltage drop under load is another reason why the AHJ should consider and have the electrician rule before signing off.
This would also provide proof that the electrical workmanship is
code complience for the builder their customers.
.. Elit could be made part of fire prevention regulations to obtain an occupancy permit.

IMO perhaps bigger then fire protection is that EFLI grantees a functioning EGC for the occupants. EFLI should be made mandatory for pools and hot tubs where an EGC is needed most. Of course what joe DIY does is up to him but new occupants have that assurance.

 

[ActionDave]

Thats something Iwire has said before to the period. Im seeing that Iwire has a lot of influence on this forum...

If it weren't for the fact he likes Billy Idol I could be his best friend.