schedule of inspections

[pushrod]

Originally Posted by ukpablo
"Double Insulation – Anything double insulated, i.e light fittings etc. These may also have metallic parts which must not be connected to earth. used to prevent the appearance of a dangerous voltage on the accessible parts of electrical equipment through a fault in the basic insulation
Reinforced insulation –similar to DI above - is a single insulation layer providing the same protection as double insultion... normally factory applied, often used in some classII equipment."

Found the above on a search could anyone tell me if swa is an example of reinforced insulation? cheers

 

[brucelee]

yes mate as far as i am aware at least the tutor reckoned it was on the 17th course as i have it marked on the example eic in the back of bs7671
but others may know better

 

[pushrod]

cheers brucelee, i was told that last night as well during my 2391 practical - must admit that i had my doubts as the armouring is not insulation and i thought it was to do with accessories anyway - i suppose they could be meaning the other extra layers in the cable - wonder if hi tuff cable is also considered reinforced insulation

Did you ever start your L3 2330?

 

[brucelee]

hi mate I wasnt sure but the tutor said it was
i tried to get on 2330 lv3 at warrington college but no one dropped out and the course remained full
i have tried C&G and bury college where i did 2391 but with no luck I have a number for a external verifier to ask but as its ending and most of the courses have started its not looking likely
I have also asked about the new 2357 at bury and got some contact details for the main electrical tutor to see if they are running it
But to get on the new 2357 I will have to be working in the game so it looks as if it will just have to wait until i set up first or a job which is probably unlikely without 2330
C&G are i cant say or i will get done lol for changing it and were does that leave adult learners who are trying to get full qualifications
tutor who i did 2391 with said i just eeded to do nVQ2356 but they not taking more candidates and as i havent started up yet wot be able to complete the required jobs for the portfolio so not good and at a loss with it all mate

oh and as for HI tuff not sure mate as i have never used it or seen it lol

 

[pushrod]

replied in PM.

 

[IQ Electrical]

Originally Posted by ukpablo
"Double Insulation – Anything double insulated, i.e light fittings etc. These may also have metallic parts which must not be connected to earth. used to prevent the appearance of a dangerous voltage on the accessible parts of electrical equipment through a fault in the basic insulation
Reinforced insulation –similar to DI above - is a single insulation layer providing the same protection as double insultion... normally factory applied, often used in some classII equipment."

Found the above on a search could anyone tell me if swa is an example of reinforced insulation? cheers

I'm struggling with this, first of all, the armouring will be earthed, even when it's not serving as a CPC but as an exposed conductive part.

If it doesn't meet the definition of an exposed conductive part, why does BS7671 stipulate the earthing of the armouring in all scenarios?

Then there is 412.2.4.1 Note 2.

 

[pushrod]

I'm struggling with this, first of all, the armouring will be earthed, even when it's not serving as a CPC but as an exposed conductive part.

If it doesn't meet the definition of an exposed conductive part, why does BS7671 stipulate the earthing of the armouring in all scenarios?

Then there is 412.2.4.1 Note 2.

they hint at things and then stop short of giving you the info you are after!!

Could it be that the part considered to be the reinforced insulation is the layer under the armouring and so is not traversed by it I bet a ***** lawyer would have problems understanding BS7671 - why can't it be written in plain english

(Have just checked the niceic learning guide to the 17th ed and an illustration in that suggests that is the case, also says there is more info about it in GN5 - unfortunately i don't have that) At least i have discovered that equipment does include wiring systems!

 

[Sintra]

also says there is more info about it in GN5 - unfortunately i don't have that)

Mate the IET are doing a free e book trial which includes BS 7671, All the guidance notes and the osg available for 30 days all these can be printed once downloaded.

Get it here

 

[IQ Electrical]

Guidance Note 5 reads:

This measure requires equipment of particular construction: only equipment with double or reinforced insulation (Class II equipment) or equipment of equivalent construction (declared as equivalent in the product standard).
It permits only the use of equipment which has no exposed-conductive-parts that can be made live in the event of a fault and thus cause danger.
The measure is generally applicable to individual items of equipment such as switchgear and controlgear assemblies, luminaires and current-using equipment, and to domestic appliances.
(Guidance Note 5: Protection Against Electric Shock, 5th Edition)

 

[pushrod]

Guidance Note 5 reads:

This measure requires equipment of particular construction: only equipment with double or reinforced insulation (Class II equipment) or equipment of equivalent construction (declared as equivalent in the product standard).
It permits only the use of equipment which has no exposed-conductive-parts that can be made live in the event of a fault and thus cause danger.
The measure is generally applicable to individual items of equipment such as switchgear and controlgear assemblies, luminaires and current-using equipment, and to domestic appliances.
(Guidance Note 5: Protection Against Electric Shock, 5th Edition)

So what is your gut feeling - swa is reinforced insulation or not?

 

[IQ Electrical]

My gut feeling is 'not' but there's a lot of ambiguity in the text!

 

[pushrod]

My gut feeling is 'not' but there's a lot of ambiguity in the text!

cheers IQ, as i said earlier that was my feeling as well but didn't really want to argue with the lecturer - i'll put my case next week.
Somewhat surprised that there hasn't been more responses definitely on one side or the other as swa is not exactly rare

 

[brucelee]

hi pushrod
our tutor told us it was and believe me he can quote every reg by number and content he even got us to put armoured at the side of the reinforced tick box on the sample schedule of inspections i thought it was only concerning items of equipment that are reinforced class 2 but he reckons it is
ive looked in regs but like you say they stop short of a deffinitive answer and as always open to interptretation
I am thinking of nipping in to the centre this week some time if i do i will ask him again
I am searching nic guide to inspection and testing nic guide to domestic inspection& testing and kitchers practical guide but still nothing that refers to it they mainly refer you to 412.1 but theres nothing stating swa is classed as reinforced insulation jsut says not suitable for domestic if the sole means of protection, but i think as it as multiple layers of insulation and the armour then i would think it does If I go ad see them this week i will let you know one is a niceic inspector and tester also so see what there take is the other is great at translating into english lol

 

[IQ Electrical]

The problem is, much of this is opinion but what about the earthed armouring, how does that fit with the definition of class II ?

I had a heated discussion last week with a 'lecturer' advising that the students tick the 'double or reinforced insulation' box due to the meter tails!!!
He only backed down after researching the difference between 'double insulated' and 'insulated & sheathed' !

It's another one for that myths thread!

 

[brucelee]

yes mate thats the problem with the regs and guides they dont go into enough detail in explaining in english
thay seem to speak there own language and as for the armour its there to protect the conductors from damage ie from spades etc also as well as having to be connected to earth and as for the tails that comes under basic protection
insulation of live parts not reinforced or double

 

[JulianC]

My interpretation is that the armour, being a conductor, cannot be an insulator or form any part of insulation. Ergo, SWA ain't reinforced/double insulated.

 

[IQ Electrical]

My interpretation is that the armour, being a conductor, cannot be an insulator or form any part of insulation. Ergo, SWA ain't reinforced/double insulated.

Not just a conductor but an EARTHED conductor, how can this comply with the criteria for class II ?

 

[JulianC]

It can't.

By definition a conductor cannot be an insulator and vice versa.

SWA offers mechanical reinforcement, not insulation reinforcement IMHO.

 

[the_mouse]

Hi, SWA reinforced insulation or not?? Well, my primary employment is cable manufacture and to achieve a certain grade we have tests on cable make up so I'll attempt to clear up some issues if i can.
The only part of a cable that is referred as insulation is the extruded material which covers the conductors, the inner extruded layer around the cores is the bedding layer, its only purpose is to protect the insulation from damage which would be caused by the steel wires during manufacture and if the cable suffered mechanical impact during service, a sort of cushion, this bedding layer is NOT subject to inline testing to ensure integrity. Next the steel wires to provide mechanical protection then finally the oversheath which provides mechanical protection, prevents moisture ingress and hold the cable all together, imagine if you cut a SWA cable with no oversheath it would fall apart, in fact some oversheaths on cables rated at 33, 66 and 132KV have a coating of graphite applied which is a very good conductor! So to answer the question is SWA reinforced insulation definitely NO, it may have three layers if insulated material but only one is actually insulation it has additional mechanical protection via the steel wire but it is not reinforced.
Think of concrete, if a concrete pillar had wire bars aplied to its outer surface it would not make reinforced but if the bars were inserted during pouring then that is makes it reinforced, in Chritpher Kitchers book, a practical guide to 17th ed wiring regs page 133 he defines reinforced insulation as a "single layer of very strong insulation"
HTH

 

[IQ Electrical]

Hi, SWA reinforced insulation or not?? Well, my primary employment is cable manufacture and to achieve a certain grade we have tests on cable make up so I'll attempt to clear up some issues if i can.
The only part of a cable that is referred as insulation is the extruded material which covers the conductors, the inner extruded layer around the cores is the bedding layer, its only purpose is to protect the insulation from damage which would be caused by the steel wires during manufacture and if the cable suffered mechanical impact during service, a sort of cushion, this bedding layer is NOT subject to inline testing to ensure integrity. Next the steel wires to provide mechanical protection then finally the oversheath which provides mechanical protection, prevents moisture ingress and hold the cable all together, imagine if you cut a SWA cable with no oversheath it would fall apart, in fact some oversheaths on cables rated at 33, 66 and 132KV have a coating of graphite applied which is a very good conductor! So to answer the question is SWA reinforced insulation definitely NO, it may have three layers if insulated material but only one is actually insulation
HTH

Thanks for that, I was pretty certain but it's nice to have some technical proof instead of interpretations of ambiguous regulations!

 

[pushrod]

Hi, SWA reinforced insulation or not?? Well, my primary employment is cable manufacture and to achieve a certain grade we have tests on cable make up so I'll attempt to clear up some issues if i can.
The only part of a cable that is referred as insulation is the extruded material which covers the conductors, the inner extruded layer around the cores is the bedding layer, its only purpose is to protect the insulation from damage which would be caused by the steel wires during manufacture and if the cable suffered mechanical impact during service, a sort of cushion, this bedding layer is NOT subject to inline testing to ensure integrity. Next the steel wires to provide mechanical protection then finally the oversheath which provides mechanical protection, prevents moisture ingress and hold the cable all together, imagine if you cut a SWA cable with no oversheath it would fall apart, in fact some oversheaths on cables rated at 33, 66 and 132KV have a coating of graphite applied which is a very good conductor! So to answer the question is SWA reinforced insulation definitely NO, it may have three layers if insulated material but only one is actually insulation it has additional mechanical protection via the steel wire but it is not reinforced.
Think of concrete, if a concrete pillar had wire bars aplied to its outer surface it would not make reinforced but if the bars were inserted during pouring then that is makes it reinforced, in Christopher Kitchers book, a practical guide to 17th ed wiring regs page 133 he defines reinforced insulation as a "single layer of very strong insulation"
HTH

Thanks mouse, brilliant response - i'll be printing out your reply