arc fault devices

Andy From Sligo

just been reading up on arc fault devices - popular in the US and Canada - but less common in UK & Ireland - you can get ones that fit into a consumer unit. Seem a very good idea and I think they should be considered into wiring regulations these days - could prevent some home and commercial and industrial fires.

They are supposed to be 'intelligent' in the fact that they will not trip/cut the circuit for things like turning light switches or appliances with motors with carbon brushes .. but apparently can detect say if there is a loose strand in a light fitting or socket and is arcing with trigger it to cut out - very clever.

the current RCCB and MCBs I dont think can detect arcing , they can only detect short circuits and overloads.


Dont think they are popular over here - saw this on the RS website but its discontinued

https://ie.rs-online.com/web/p/industrial-surge-protection/7999128/

has anyone (ie any electricians on here) ever fitted one ? / used them?

Risteard81

Arc Fault Detection Devices (AFDDs) have been introduced into the 18th Edition of the IET Wiring Regulations, which comes into effect from the 1st January 2019. The Standard recognises the devices and recommends their use. Most manufacturers have not yet released their devices. Those that have attract a price tag which might put you off having them in your installation!

In the US they are known as AFCIs (Arc Fault Circuit Interrupters).

The National Rules for Electrical Installations here is due to have its 5th Edition released next year. As the Draft for Public Comment has not yet been released I have no idea whether AFDDs will feature within this, much less the final version of the Standard. This will be published as I.S. 10101 - an Irish Standard.

Tuco88

Risteard81 wrote: »

Arc Fault Detection Devices (AFDDs) have been introduced into the 18th Edition of the IET Wiring Regulations, which comes into effect from the 1st January 2019. The Standard recognises the devices and recommends their use. Most manufacturers have not yet released their devices. Those that have attract a price tag which might put you off having them in your installation!

In the US they are known as AFCIs (Arc Fault Circuit Interrupters).

The National Rules for Electrical Installations here is due to have its 5th Edition released next year. As the Draft for Public Comment has not yet been released I have no idea whether AFDDs will feature within this, much less the final version of the Standard. This will be published as I.S. 10101 - an Irish Standard.

Have Crabtree/siemens released one yet? Looks to be the next "thing" I agree on the price...

Risteard81

Tuco88 wrote: »

Risteard81 wrote: »

Arc Fault Detection Devices (AFDDs) have been introduced into the 18th Edition of the IET Wiring Regulations, which comes into effect from the 1st January 2019. The Standard recognises the devices and recommends their use. Most manufacturers have not yet released their devices. Those that have attract a price tag which might put you off having them in your installation!

In the US they are known as AFCIs (Arc Fault Circuit Interrupters).

The National Rules for Electrical Installations here is due to have its 5th Edition released next year. As the Draft for Public Comment has not yet been released I have no idea whether AFDDs will feature within this, much less the final version of the Standard. This will be published as I.S. 10101 - an Irish Standard.

Have Crabtree/siemens released one yet? Looks to be the next "thing" I agree on the price...

I believe that Siemens have. Haven't heard about a Crabtree one though. I know that Hager's device isn't quite there yet (unless this has changed very recently).

Andy From Sligo

I think it will a great addition to the consumer board and the regulations - Ive come across things like loose screw terminals on 13a plug pins and some sparking inside laptop power supplies and phone chargers (especially if they have shoddy dry solder joints) - so (if they work and are effective) yeah I think they will be a good idea and hopefully prevent a lot of fires due to things sparking but not actually directly shorting out.

Any reason why they should be a much higher price of that of an RCCB say? - must be similar kind of mechanics/electronics inside?

Andy From Sligo

Tuco88 wrote: »

Have Crabtree/siemens released one yet? Looks to be the next "thing" I agree on the price...

this seems to be a siemens one:

Andy From Sligo

Andy From Sligo

just looking at the AFDD on ebay Germany - they are up into the hundreds of euro for 1 :eek:

Risteard81

Andy From Sligo wrote: »

just looking at the AFDD on ebay Germany - they are up into the hundreds of euro for 1 :eek:

Don't say I didn't warn you!

Andy From Sligo

Risteard81 wrote: »

Don't say I didn't warn you!

didnt doubt you, still surprised though - this price could put some people off , and make them cut corners - although I think residential and commercial buildings should have these as they exist and seem a good form of protection I actually think for a start that all commercial premises should have these fitted as standard whether they are having a new build of consumer unit or even if they retrofit these ones - commercial / industrial could maybe afford to swallow the outlay of them but pricey enough - as they become more popular and even more widely used they surely will come down in price wont they?

Risteard81

Andy From Sligo wrote: »

Risteard81 wrote: »

Don't say I didn't warn you!

as they become more popular and even more widely used they surely will come down in price wont they?

I would think that is a fair assumption, but we are a hell of a long way off that yet. With BS7671 not mandating the devices yet then they will presumably have limited uptake in Britain or in the Six Counties. (Perhaps some commercial/industrial applications where it is seen as worthwhile.) So it will be another three years until the 1st Amendment to the 18th Edition whereby there is a chance that AFDDs will be pushed a bit harder than currently.

As I say it remains to be seen what the 5th Edition of the Wiring Rules here will say on the matter (if anything).

Thammer

Andy From Sligo wrote: »

didnt doubt you, still surprised though - this price could put some people off , and make them cut corners - although I think residential and commercial buildings should have these as they exist and seem a good form of protection I actually think for a start that all commercial premises should have these fitted as standard whether they are having a new build of consumer unit or even if they retrofit these ones - commercial / industrial could maybe afford to swallow the outlay of them but pricey enough - as they become more popular and even more widely used they surely will come down in price wont they?

Industry and commercial would be concerned with equipment protection as they have better standards of enclosure and fire safety in installation work.

They will probably become mandatory in domestic for protection of persons and property.

How do these devices differ from phase failure protection devices which would be situated close to equipment,I don't know much on the matter tbh.

EdgeCase

They've always been more concerned with electrical fire risks in North America largely because of the building materials they use. Most homes are almost entirely wooden structures so any small electrical fire carries huge risks.

In general in European construction, the structures are full of concrete and the wiring is often sitting in plaster.

That's likely why you've seen faster adoption of arc fault detection.

European wiring systems saw much earlier and more universal adoption of RCDs. (The UK being very late to follow that trend). The regulations in the USA and Canada tend to only use RCDs in wet areas.

Thammer

The fire risk is probably greater alright in the US

They have better standards of containment and enclosure than here for domestic anyhow so that would reduce the overall risk

EdgeCase

That’s why though.

They typically mandated things like flexible or solid metal conduit and very heavy duty metal boxes to contain fire.

The low voltage (110-120V) tends to also mean you get far more 15/20Amp circuits running almost maxed out too. Considering they can only realistically deliver 2400W absolute max at 20amps. 230V systems tend to give a bit more margin for heavy loads.

The risk of a fire in those old clapboard houses is huge. I know in Boston for example all the old streets had “fire pulls”. Fire risk was such a big concern that in the days before telephones there were levers on the street to call the fire department!

Andy From Sligo

EdgeCase wrote: »

They've always been more concerned with electrical fire risks in North America largely because of the building materials they use. Most homes are almost entirely wooden structures so any small electrical fire carries huge risks.

In general in European construction, the structures are full of concrete and the wiring is often sitting in plaster.

That's likely why you've seen faster adoption of arc fault detection.

European wiring systems saw much earlier and more universal adoption of RCDs. (The UK being very late to follow that trend). The regulations in the USA and Canada tend to only use RCDs in wet areas.

When i worked on a Electrical Trade counter in a builders providers in the UK in the late 1980's we used to sell Wylex ELCB's for consumer units way back then - when i moved to Ireland in the 90's I think still bottle fuses and just a plain DP mains switch was the norm, i think even for new builds (well residential)

Thammer

Andy From Sligo wrote: »

When i worked on a Electrical Trade counter in a builders providers in the UK in the late 1980's we used to sell Wylex ELCB's for consumer units way back then - when i moved to Ireland in the 90's I think still bottle fuses and just a plain DP mains switch was the norm, i think even for new builds (well residential)

Not for news builds no, in the mid 90s

I was registered at that stage ,we were on to neozed main switch fuses and RCDs/mcbs by then

DZ fuses and rcds were standard for new builds in the 80s here too

manufan16

some information on afdd

http://www.hager.co.uk/news-exhibitions-case-studies/18th-edition/arc-fault-detection-devices/89766.htm

Thammer

Domestic fires caused by arcing would be less of an issue now due to improved wiring standards

Is there any stats on this?

From a domestic standpoint Afdd's look like rcds in this regard.

They would be more of an addition to a good electrical installation than a necessity

EdgeCase

Andy From Sligo wrote: »

When i worked on a Electrical Trade counter in a builders providers in the UK in the late 1980's we used to sell Wylex ELCB's for consumer units way back then - when i moved to Ireland in the 90's I think still bottle fuses and just a plain DP mains switch was the norm, i think even for new builds (well residential)

I've a house wired in 1978 with all MCBs and an old style lever RCD only recently updated.

The bottle fuses were often used in combination with RCDs too btw. There was nothing wrong with diazed fuses. They were actually a lot more secure than the old rewirable Wylex type that were used in Britian.

ELCB was not a differential RCD. It was normally a voltage operated device used with TT supplies.

Also DP mains switches aren't normal here. There's usually a 63amp fuse and switch combination on the board.

Diazed fuses may look old-fashioned but they were an extremely solid system that was used all over Northern Europe. They weren't easily tampered with by inserting a higher rated fuse either and were generally used as designed. The Wylex old type fuses used rewirable holders that assumed you knew what you were on about when replacing a fuse. Diazed and neozed have disposable porcelain cartridges with non interchangeable sized tips. There was no real risk of someone popping a 32Amp fuse into a 16Amp holder without considerable tampering with the rings.

There was considerable conservative resistance by some people to moving to MCBs.

The biggest issue with diazed and neozed was they were inconvenient as you needed a stock of fuses in the house to reset them.

RCDs actually became the norm here before MCBs replaced Siemens "Zed" fuses.

Andy From Sligo

we used to sell the Wylex MCB's that replaced the re-wireable Bakelite ones . that was a good Idea , meant that if you didnt want to upgrade the whole CU you could at least replace a the old bakelite ones with a breaker.

Yes, your right I think from memory, Irish used SP mains switch and UK had DP mains switch isolater in the CU - even today regulation I think still using SP isolator in the consumer unit.

that really surprising about RCD's and MCBS used in your CU in 78 - when i first moved to Ireland and were pricing up CU for a cottage we were renovating I went to a electrical trade counter in town and they were showing me the CU's with Siemens diazed fuses - maybe it must have been because i was asking for the cheapest consumer unit - I cannot remember if i asked at the time about RCD and MCB's

Andy From Sligo

went on a course once (think that was with wylex) with work and they showed us the response time of a 20a fuse wire blowing (glowing first before melting) - I think the 20a actually melted in the end measured at 35a or something cannot remember) and how quickly an 20a MCB tripped on a fault in milliseconds

EdgeCase

There's a trip curve for each type of RCD (that's what the letter indicates) and there are similar specifications for fuses. It would very much have depended on the type of fuse wire that was used in the Wylex fuse.

There's nothing inherently wrong or dangerous about fuses, if they're installed correctly and to the right specification.

Off hand, I don't know the profile of the fuses that were used in the DZ and NZ holders here but they seemed to provide a fairly decent level of protection. They certainly did blow fairly rapidly when overloaded, and definitely sooner than the fuses in the plugs.

You don't necessarily want a fuse or an MCB to blow instantaneously on a fault. They have to cope with inrush surges and so on that are just momentarily. It's more of an issue with industrial motors and so on, but even in houses you don't want the MCBs tripping every time you turn on something with a very large motor.

A halogen light popping can sometimes cause a big enough surge to trip an MCB and actually pop DZ fuses too.

The old UK Wylex fuses would probably still have blown long before the house wiring caught fire though. That's all they had to do.

There were actually screw-in MCBs that fitted into the DZ bases, but they were pretty rare here. They're common enough in Germany (or were anyway).

The DP isolator here would be deemed unnecessary on 'neutralised' supplies i.e. the neutral is grounded and also cross bonded to the plumbing. Technically speaking, if you're being really pedantic (as someone here clearly is) you shouldn't be switching naturals.

EdgeCase

BTW Diazed and Neozed are a Siemens originated standard that was (and still is) quite widely used. They still crop up in industrial application where fuses may be preferable.

https://en.wikipedia.org/wiki/IEC_60269#D_type_fuses

You'd have actually found D-type fuses in some industrial applications in the UK too btw.

They were used very extensively right cross continental Europe, with the only exceptions that I'm aware of being the UK and France.

The old French system used small cartridge fuses that look a bit like our current switch-fuse holders but took a different shape fuse and before that they were big ceramic plug in fuses with two pins.

Andy From Sligo

them ol UK bakelite ones blew with a big bang! when they blew - much nicer hearing an MCB or RCCB trip nowadays - and when renewing the old bakelite fuse wire in the carriers you could see scorch marks where the fuse wire melted . - when we were in a DIY shop we used to buy a 'card' with fuse wire wrapped around it - I think 3 sizes 5a /20a and 40a fuse wire I think it were - quite tricky / fiddly wrapping it around the terminals and holding it whilst tightening up the terminal screws - in that case replacing a bottle fuses would have been a breeze.

and yes, when you think now what a system that was it makes you think there werent more house fires - you could literally take out a 5a rewireable fuse carrier out of the fusebox and not have any 5a fuse wire but a 20 or 30a fuse wire in its place and with the " i will replace it with the right fuse wire tomorrow when I go out tomorrow and get some" line ...

EdgeCase

I'd say the loud bang was because the fuse was pretty much exposed to the air and wouldn't have been sitting in sand.

DZ and NZ cartridges would be manufactured and sealed, so they wouldn't make more than a pop when they go and they definitely don't scorch anything. The same would apply to BS cylindrical cartridge fuses.

The DZ cartridge has a little disc at the fat end that falls outwards when the fuse blows, so you can see that in the glass window on the holder to identify which fuse had gone. It works in theory but often didn't pop out.

Andy From Sligo

in our present house we are in , built in 2008, CU has bottle 63a fuse in the SP AEG isolator -

EdgeCase

Yeah, that would be the norm.

It's usually either a switch and fuse in series as separate units on a DIN rail or a combined switch/fuse unit that does both functions.

AFAIK, MCBs in lieu of a main fuse are only very recently being accepted as an alternative.

What I have heard (and I'm open to correction on this) is that there was reticence to rely on a mechanical device as a fuse will almost certainly blow in a catastrophic fire situation.

They really are very conservative about some of these fundamental safety devices.

The consumer's main fuse is there really to avoid overloading the incoming main and inadvertently blowing the ESB fuse, should something go wrong and the whole system were to become overloaded.

I mean if you max out all of your final circuits for some reason, you could very easily go beyond the supply limit for the house.

63A = 14,490W

You could conceivably blow the ESB fuse on a cold Christmas Day if you plugged in several electric heaters and had the ovens all running and maybe threw on an electric shower. No system is designed for absolutely everything to be on simultaneously.

If heat pumps are going to become part of the heating mix here in a big way and electric cars and so on, 63amp supplies aren't going to cut it.

The main reason that the US and Canada have tended to have very much bigger mains supplies i.e. up to 200A as standard, was down to huge air conditioning loads / heat pump loads. We get away with fairly skimpy supplies in Ireland (and the UK too) due to having no really big demands.

A lot of Northern European countries would have 400V 3-phase power into homes that have any kind of serious load. It's actually brilliant if you need to use large motors for air conditioning / heat pumps and so on.

Andy From Sligo

EdgeCase wrote: »

Yeah, that would be the norm.

It's usually either a switch and fuse in series as separate units on a DIN rail or a combined switch/fuse unit that does both functions.

AFAIK, MCBs in lieu of a main fuse are only very recently being accepted as an alternative.

What I have heard (and I'm open to correction on this) is that there was reticence to rely on a mechanical device as a fuse will almost certainly blow in a catastrophic fire situation.

They really are very conservative about some of these fundamental safety devices.

The consumer's main fuse is there really to avoid overloading the incoming main and inadvertently blowing the ESB fuse, should something go wrong and the whole system were to become overloaded.

I mean if you max out all of your final circuits for some reason, you could very easily go beyond the supply limit for the house.

63A = 14,490W

You could conceivably blow the ESB fuse on a cold Christmas Day if you plugged in several electric heaters and had the ovens all running and maybe threw on an electric shower. No system is designed for absolutely everything to be on simultaneously.

If heat pumps are going to become part of the heating mix here in a big way and electric cars and so on, 63amp supplies aren't going to cut it.

The main reason that the US and Canada have tended to have very much bigger mains supplies i.e. up to 200A as standard, was down to huge air conditioning loads / heat pump loads. We get away with fairly skimpy supplies in Ireland (and the UK too) due to having no really big demands.

A lot of Northern European countries would have 400V 3-phase power into homes that have any kind of serious load. It's actually brilliant if you need to use large motors for air conditioning / heat pumps and so on.

am just trying to think from memory what the average UK house has as its main utility fuse next to the meter and I think its 80a as the norm in a bakelite holder and no fuse on the isolator , just a DP mains switch ... or maybe no mains switch at all now, just a 80a 30ma RCCB

when you think , nothing to a house having at least 2 9Kw showers these days thats 18,000w so 63a for total in a CU is not that much - mind u I suppose thats when interlocks come into play in the CU allowing you only to use one 9kw shower at a time



-

Risteard81

Andy From Sligo wrote: »

EdgeCase wrote: »

Yeah, that would be the norm.

It's usually either a switch and fuse in series as separate units on a DIN rail or a combined switch/fuse unit that does both functions.

AFAIK, MCBs in lieu of a main fuse are only very recently being accepted as an alternative.

What I have heard (and I'm open to correction on this) is that there was reticence to rely on a mechanical device as a fuse will almost certainly blow in a catastrophic fire situation.

They really are very conservative about some of these fundamental safety devices.

The consumer's main fuse is there really to avoid overloading the incoming main and inadvertently blowing the ESB fuse, should something go wrong and the whole system were to become overloaded.

I mean if you max out all of your final circuits for some reason, you could very easily go beyond the supply limit for the house.

63A = 14,490W

You could conceivably blow the ESB fuse on a cold Christmas Day if you plugged in several electric heaters and had the ovens all running and maybe threw on an electric shower. No system is designed for absolutely everything to be on simultaneously.

If heat pumps are going to become part of the heating mix here in a big way and electric cars and so on, 63amp supplies aren't going to cut it.

The main reason that the US and Canada have tended to have very much bigger mains supplies i.e. up to 200A as standard, was down to huge air conditioning loads / heat pump loads. We get away with fairly skimpy supplies in Ireland (and the UK too) due to having no really big demands.

A lot of Northern European countries would have 400V 3-phase power into homes that have any kind of serious load. It's actually brilliant if you need to use large motors for air conditioning / heat pumps and so on.

am just trying to think from memory what the average UK house has as its main utility fuse next to the meter and I think its 80a as the norm in a bakelite holder and no fuse on the isolator , just a DP mains switch ... or maybe no mains switch at all now, just a 80a 30ma RCCB

when you think , nothing to a house having at least 2 9Kw showers these days thats 18,000w so 63a for total in a CU is not that much - mind u I suppose thats when interlocks come into play in the CU allowing you only to use one 9kw shower at a time



-

Either 60A, 80A or 100A fuses may be in a UK domestic installation. A single phase domestic installation must have a main switch which breaks all live conductors (i.e. double pole) for BS7671 compliance. Very different setup to ET101.

Thammer

From memory the UK domestic was 100 amp

DP main isolating switch as there was different service types,TT etc

Risteard81

Thammer wrote: »

From memory the UK domestic was 100 amp

DP main isolating switch as there was different service types,TT etc

It's either 60A, 80A or 100A and is essentially up to the individual DNO.

Double pole main switch is because domestic is not under the supervision of electrically skilled or supervised persons so is irrespective of supply type. However this Regulation does not apply to a three-phase installation with a TN supply (Either TN-S or TN-C-S).

Andy From Sligo

sure anyway with the Irish system even if you have a single pole mains isolator switch it normally (on newer systems anyway) the next hardware in the CU is a RCCB anyway and thats douple pole so when you kill that switch your disconnecting the neutral anyway arent you to the rest of the house wiring?*

*well apart from a split system - whereas the part of the CU is not protected by a RCCB still has neutral connected

EdgeCase

What is the logic of the single pole main switch here?
I'm assuming it's sticking rigidly to the idea what a neutral shouldn't be switched due to possible bonding implications ?

(Although bonding would be done at the meter, so shouldn't be disconnected by the switch anyway)

Andy From Sligo

EdgeCase wrote: »

What is the logic of the single pole main switch here?...

its not because of this I am sure , but I have often thought with mechanical double pole switches like this with phase and neutral going into one switch like this if they fell to bits/disintegrated - you have a direct short there and in this case it would blow the main (you would hope) utility fuse next to the meter. - at least with one pole at least you have the neutral no-where near the live terminal

but most people when they are working on something electrical in the home would feel more comfortable in the knowledge that both Live & Neutral are both disconnected when you turn of the mains switch (maybe most people believe they have killed both L and N when they turn off the mains switch in the CU in Ireland because there is no tell tale sign to most that its just a SP switch) so if they kill the mains switch and unscrew that bulb in the ceiling light pendant fitting and the bulb breaks they have only killed the live to the fitting and not the neutral (if the lighting circuit is not going though an RCCB in the CU - some split boards only put the RCCB on the sockets and dont have an RCCB on the lighting circuit)

But yes - most probably the something to do with the earth system bonded to the neutral over here and dont want to put DP switch in because it would interrupt the neutral/earth bonding system

Am sure an electrician on her could explain it away better than I can...

Thammer

EdgeCase wrote: »

What is the logic of the single pole main switch here?
I'm assuming it's sticking rigidly to the idea what a neutral shouldn't be switched due to possible bonding implications ?

(Although bonding would be done at the meter, so shouldn't be disconnected by the switch anyway)

It's because there's no need to switch it for main isolation here as the neutral is reliably at earth potential

At the appliance end it's safer for the consumer to switch both poles and convenient for installation testing

Andy From Sligo

Thammer wrote: »

It's because there's no need to switch it for main isolation here as the neutral is reliably at earth potential

At the appliance end it's safer for the consumer to switch both poles and convenient for installation testing

not all switches on all 13a sockets are DP though are they - 20a spurs are normally DP I think .. and then light switches are SP

EdgeCase

No they’re generally only DP if it’s specifically mentioned. The switches are entirely optional too. Some of the better brands like MK definitely use DP switching but I certainly wouldn’t rely on all 13 amp sockets cutting both poles and also I wouldn’t be entirely convinced that they’re always reliably wired in the correct polarity either.

If you’re working on something - the plug should be pulled out of the wall socket entirely.