GFCI *breaker* failure modes?

[attrs elided]

Note that I can use relatively large loads without it tripping (see )

So, I will try to probe the potential ON THE BLADES of the load's plug in an attempt to see what sort of resistance is present in the wiring at these loads (e.g., 1KW). Using "earth" as my "0V" reference and a relatively high impedance DVM (to avoid tripping the GFCI by this "measurement current").

That's tedious as the boxes are weatherproof (so, lots of screws holding the weatherproof covers on OVER the receptacles).

Also, I would prefer to *see* the failure, hypothesize a cause and then institute a remedy (even if that remedy is as simple as cleaning the crud OR replacing the receptacles) and VERIFYING the problem has "disappeared". I.e., to see a definite cause and effect.

I've found my HiPot but the fuse has been removed and I don't recall why I did that. But, know it can't be a good sign! (cuz I have plenty of spare fuses!). So, I'll now have to sort out the state of that tester, as well.

Sheesh! Nothing is ever easy!! But, hopefully, we won't see any cold weather for another few months so I've got time to suss it out.

Circuits are usually mixed lighting and receptacle. I can't remember a residential circuit that was just lighting.

But you could write a code change proposal to advance the march of AFCIs to take over the world.

I don't believe the NEC allows cord connected furnaces or plug connected furnaces.

A common reason to deny a code change proposal is that evidence has not been presented that the proposal will make safer wiring. I think the evidence for AFCIs has been minimal and anecdotal - not a good idea. Improved safety will generally be in the future when new wiring becomes old wiring.

GFCI protection is required for residential kitchen counter top receptacles.

There is no current requirement for AFCI residential kitchen protection. I have read that it will be required in the 2014 NEC (whenever that provision is accepted where you live).

AFCIs don't replace GFCIs. GFCIs trip with 5mA ground fault, AFCIs with about 30mA ground fault. Another question is whether GFCIs trip faster.

In the UK, the lighting would be put on two or more protected circuits such that if one RCD should trip there is still some lighting. Older regulations didn't require a RCD fitted to a lighting circuit on the basis that the risk associated with darkness was greater than electric shock.

I thought we in the UK were anal about fault currents, but your GFCI/AFCI of 5/30mA are equivalent to RCDs of 30/100mA.

Our allowable leakage current levels are so much higher, and I'm left wondering why.

The only reason I can attribute is the behaviour difference between

110/230V and the way the body/inflammable material responds to the voltage-current combinations.

--
Mike Perkins 
Video Solutions Ltd 
www.videosolutions.ltd.uk

I never said a load is needed for a GFCI to detect a N-G short. You must have missed the word "without" in what I wrote.

Correct, Rb simulates the fault. There is no load connected.

Not new at all. We've been discussing a N-G fault resistance and a N-G short all along. It confirms what Bud said.

Thanks. I know about GFCIs, but have no experience with RCDs. I gather that RCD is the correct term to use when talking about the Australian equivalent of what we call a GFCI.

Ed

** You are an illiterate jerk. ** Funny how it is across A and N then...... ** Fraid it is new.

You need to learn to read sometime.

** Yawnnnnnnnnnn....

Remedial reading classe are available at your local Community College.

Remedial thinking is however another matter.

... Phil

Your opinion does not change the fact that you missed, or did not understand, the word "without".

There is no "A" shown in the diagram. Rb is shown across live and neutral and is identified in the datasheet text as follows: "Rb represents a normal ground fault resistance."

Read the datasheet text.

Fraid you're wrong. My post date/time stamped 9/22 at 3:48 AM discusses, and is the first mention of, the RV4141A. Your first post the mentions the RV4141A is stamped 9/24 at 6:38 PM

Both the datasheets mentioned show _TWO_ current transformers, which bud mentioned and with which you disagreed. To remind you, here's what you wrote in your post date/time stamped 9/21 at 10:40 PM replying to bud:

First you quoted Bud: "There is a second current transformer that tries to put a small common mode current in both the H and N wire."

You replied" "** Hogwash."

In your post stamped 9/24 at 6:38 PM you quoted Bud and responded as follows:

Bud said: "GFCIs have a second CT to immediately trip on N-G shorts with no load."

Your reply was: "** This one is different to your example.

"

A look at the datasheet in the url _CLEARLY_ shows _TWO_ current transformers, precisely what Bud was talking about.

You also said: " No injected current and there is a load present."

If your point is some quibble about the word "injected", Bud did not use it - _you_ did. Bud's sentence was "There is a second current transformer that tries to put a small common mode current in both the H and N wire."

You have been proven wrong on the current issue, whether you want to quibble with your own use of the word "injected" or fail to recognize that inducing a current is done by that transformer.

PKB

Try taking one - you need it.

Yes, you demonstrate that quite well, whenever someone disagrees with what you've posted. And in the above, you demonstrate it when someone thanks you for something you've posted.

Reading what you write about electronics is interesting and worthwhile, even if at times there may be some disagreement with what you posted. However, when you post your opinions of other posters, the value of what you write is zero.

Ed

This is only sometimes true. Older installations usually have neutral linked to earth only at the substation transformer and not at the premises (TN-S). Gas and water service pipes are bonded to the incoming mains earth near the entry to the premises. However, many properties now have "protective multiple earthing" (PME or TN-C-S) supplies where the neutral is earthed at multiple points in the distribution system. In a PME installation the earth wiring within the property is linked to neutral at the point where the incoming two-core supply cable is terminated, just before the meter. Gas and water service pipes are bonded to that earth/neutral point. In newer properties both gas and water are supplied through plastic pipes, so in this case only the internal plumbing is connected.

Usually, but not always. Radial circuits are allowed.

John

** It is generally the case.

You stupid, context shifting, Google Groups troll.

No context shifting - you asserted something that I disagreed with.

It is hard to find relative numbers, but in general old properties have TN- S earthing and new properties (last thirty years or so) have TN-C-S / PME.

Electricity suppliers certainly think that they mostly install TN-C-S / PME .

See for example:

lers.aspx

They state: We provide PME (protective multiple earthing) facilities as standard at the vast majority of new electricity connections. In some cases we can also i nstall a PME earthing terminal at existing non-PME installations, although this does depend on the design of our electricity system and on the type of installation.

In case you think I am cherry-picking just one power supplier, here is a qu otation from an engineering design standard (EDS 06-0017) used by another l arge supplier:

Protective Multiple Earthing (PME) is the most common form of earthing prov ided at new installations. A single conductor for neutral and earthing func tions is utilised and an earth terminal is provided at the customer?s ins tallation. The customer?s earthing may be connected to this terminal prov iding the relevant requirements in BS 7671 are satisfied. In some cases it is not appropriate to provide a PME earth terminal, either due to the natur e of the distribution system or due to the type of installation itself.

As for using google groups for posting - sorry about that - I'll get round to using a proper usenet service sometime.

John

No context shifting ...

** Fraid it is.

.... Phil