Arc Fault Circuit Interruptors

Page 3 of 3  
Huge wrote:

US reader here. Our Code (NEC) is truly national in scope and application. Local jurisdictions may opt to require higher standards than the Code specifies and some large cities do that.
New construction has been required for some years to equip all receptacles (outlets) with GFCI (RCD) protection when located in baths, unfinished basements, garages, and outdoors. Kitchen countertops were added to that. The protection may be included in the branch circuit breaker feeding the outlets or may be part of the receptacle (such as the Leviton reference given).
Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
C-H Gustafsson wrote:

How ? 20mA to ground is hardly a major power dissipation.
Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 18 Dec 2003 12:31:36 +0000, roger

Not commonly.

No. As Andrew has said they are designed to overcome a number of deficiencies which are almost confined to the USA. The combination of low voltage means higher currents and in conjunction with what we would consider to be poor standards of wiring, components and particularly jointing makes the system vulnerable.
The most common fault is an overheating connection which simply sits and arcs away gently (often for weeks) until things degrade sufficiently for it to fail (The American series "CSI" featured such a theme in one program). When it fails it fails by getting very hot and melting/burning. American houses are commonly timber frame built with little regard for fire prevention or control and fires can develop within the wall spaces with great speed.
--
Peter Parry.
http://www.wpp.ltd.uk/
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi
So how do AFCIs work? do they detect higher frequencies than the 60Hz? Do they detect current flowing at cycle peaks but not near zero? Anyone know?
Regards, NT
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are several types of AFCI:
http://www.ul.com/regulators/afci/index.html
For detecting series arcing: o Break in say vacuum cleaner or laundry iron flex Live conductor o Both are *very* common in the UK
Neither fault will cause an MCB or RCD/RCBO to trip, unless there is an (eventual) carbon path to earth which may take some time.
For detecting parallel arcing: o Traditional L-N arcing which may not trip the MCB o Generally this is higher current so MAY soon involve L-E
The more advanced AFCI cover both.
AFCI is something the UK could benefit from on ring-mains, with irons & vacuum cleaner flexes coming under very severe duty. I've seen 2 of my own vacuum cleaner flexes fail near the plug, and the Philips irons (butyl, cotton-covered, not silicone) can overkink or even have cable kinked in the box - a series arc fault in waiting.
Remember arc temps can be *extremely* high indeed, and easily enough to ignite magnesium let alone typical insulation/dust etc. -- Dorothy Bradbury www.stores.ebay.co.uk/panaflofan for fans, books & other items http://homepage.ntlworld.com/dorothy.bradbury/panaflo.htm (Direct)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 20 Dec 2003 18:30:07 -0000, "dorothy.bradbury"

A strong case for never using a vacuum cleaner by the sound of it.
--
Peter Parry.
http://www.wpp.ltd.uk/
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The 2 failures were over 18yrs admittedly. Both cables failed within 1" of the plug, one moulded-on & one not.
The iron failure was most disturbing as it was in 10 months, with nothing but usual wrap-the-cable-around-the-iron base storage. It wasn't wrapped kinked, the cable was supplied kinked in the box and the normal use buckled the inner cores into a "knot". Then it smoked one day, series arc smouldering away.
Silicone iron cables (eg, higher end Tefal) don't suffer from this.
Yes, I don't care much for vacuum cleaners. For arthritis I use 2 Miele's, a 300 & 400 for down & up (HEPA). Both are quite heavy, and the castors just sink into carpet - I'm sure they were sized for hard floors where they are super-smooth.
Ended up using a Miele-hose-coupler & extra hose to double the hose length so it reaches down the stairs instead of chasing me down.
However, a central vacuum cleaner has always interested me: o Quieter, re non co-located o Long light hose without rigid couplers to roll on :-) o No heavy motor unit & cable to drag about, fail or fall over
The USA ones have dust-bins more suited to CNC-Machining-R-Us and an overall size which threatens to suck up late postman (ok, which I might use to threaten to suck up late postman, I admit it).
There is a market for something smaller. Considering the under-stairs location, with above-upper-floor socket and below-lower-floor socket, it's not difficult to implement one really. The hoses can be a pain, since ~20-30ft of hose has a mind of its own.
Less chance of the cat making it to the bag anyway :-) -- Dorothy Bradbury
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"dorothy.bradbury" wrote | [central vacuum cleaners] The USA ones have dust-bins more suited | to CNC-Machining-R-Us and an overall size which threatens to suck | up late postman (ok, which I might use to threaten to suck up late | postman, I admit it).
Upon first reading, I wondered why you were accumulating deceased carriers of Her Majesty's Mails about your premises :-)
Owain
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Post office wish to do the same, even their mail has been rough lately :-) -- Dorothy Bradbury
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Surely though, the fact that both appliances were well-used portable devices means that, even without an Arc-Fault device there is little real danger - unless that is you're in the habit of leaving the iron switched on between sessions? I think anyone smelling smoke from the vicinity of an appliance they are currently using will whip the plug out sharpish. Also, a series fault is most likely to begin to manifest itself in random cutting-out of the appliance, at which point most people will rapidly get very annoyed and either arrange a repair or (more likely these days) bin the thing and buy new.
I can see the use of an AF device where fixed wiring or permanently wired equipment is prone to such a failure, but as has been argued in this thread, this seems to be more a feature of the bad wiring practice in the US than here. The occasional user who regularly runs over an extension lead on his office chair excepted, of course :-)
The temptation due to cost, surely, will be to fit AF devices to cover several circuits at once. This is already the case with RCDs, and look at the arguments we've had here recently about the merits of this! The alternative is to fit devices individually to circuits requiring such protection. I know it's a bit of a false comparison, but 60 from Screwfix for a 12-way split board with main switch, RCD and 10 MCBs just doesn't compare with 20 for a 9-way board with main switch and 9*30 for RCBOs.
Hwyl!
M.
--
Martin Angove: http://www.tridwr.demon.co.uk /
Two free issues: http://www.livtech.co.uk/ Living With Technology
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

In the case of a portable appliance which fails in use, you are extremely unlikely to be hurt, and you are present to take the measures necessary to remove further risk of danger. I've had an iron flex go bang and I've had other appliance flexs simply lose continuity when the conductors break, but spectaclar as the iron was, I wasn't ever in any series danger. I suspect there are far more effective ways to spend the money and improve safety in the UK than by installing AFCI's.
The problem in the US is this type of thing happens inside the building fabric where you might not be aware until there's a sizable fire burning in an area you have no access to, like inside a partition wall.
--
Andrew Gabriel

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.