Can we use the armour of an SWA as the CPC???

[malcolmsanford]

The mind just has to boggle at some of these so called competent to teach Electrical lecturers these day's.

I know mate I sometimes just can't believe what is happening to our industry.

Not this young lads fault but the institution.

Apparently teaching someone to run a cat cable and terminating a RJ45 plug is considered more relevant to an electrician than running and terminating MICC.

 

[johnny999]

Sorry guys that was taught, it can corrode or come loose in the gland therefore not giving adequate continuity.

 

[malcolmsanford]

Johhny your quite right it can corrode in certain environments and of course it can come loose.

But IMO you should be taught all types of erection methods. I may very well feel as the designer that running an SWA in a ship yard or perhaps a chemical store will most likely have a corrosive affect on the armour. But if that was the case I would be looking at another method, perhaps galvanized trunking/conduit or even sheathed MICC, but if SWA was the best method then yes I would most likely run a 3 core using the 3rd core as your CPC.

As for the remark about it maybe coming loose well you could say that about any form of termination even the 3rd core of your SWA in a screw terminal.

I just feel that by blanketing use of "always using a 3rd core of a SWA as a CPC" is depriving you the student of designing an installation that is safe and the best for it intended use, as well in a lot of cases it's most cost effective.

 

[johnny999]

I think the course I was on ( 3yrs @ 1 day a week ) was symptomatic of the way this country has gone in the last few years, "keep it simple & go heavy on the Health & safety". I have lots of questions to ask which most of you will roll your eyes at.

 

[Guest123]

I think the course I was on was symptomatic of the way this country has gone in the last few years, "keep it simple & go heavy on the Health & safety".

In a nutshell.

I am astonished that you have been taught in this fashion, rather than outlawing it due to possible deterioration, they should be showing you how to install it in order to protect against the problem.

I despair, I really do!!!!:mad2:

 

[malcolmsanford]

I think the course I was on ( 3yrs @ 1 day a week ) was symptomatic of the way this country has gone in the last few years, "keep it simple & go heavy on the Health & safety". I have lots of questions to ask which most of you will roll your eyes at.

Don't be afraid Jonny to come on and ask questions son, the majority on here are more than willing to try and fill gaps left in your training.

as I said in my post to you, it's not your fault that your trained in this way, and a few of us older lags would have trained you properly, or at least shouted at you properly.............

 

[i=p/u]

s = i sauared x time, square rooted and divided by k

example 20A type b

100x100x0.4 =4000 square rooted = 63.2 divided by 51(k value) from table 54.4= 1.2mm swa core you need as minimum....

 

[i=p/u]

abc. defg

 

[Engineer54]

I know mate I sometimes just can't believe what is happening to our industry.

Not this young lads fault but the institution.

Apparently teaching someone to run a cat cable and terminating a RJ45 plug is considered more relevant to an electrician than running and terminating MICC.

Malcolm,

It even seems that these so-called lecturers are teaching students to favour radial circuits over RFCs !!! It's not going to be long, if that continues, that the sparks of tomorrow will be gasping in despair at the thought of having to fault find a ring circuit let alone test one!!

I think the whole curriculum of student training, needs a good kick up the arse. Just wait and see all the lecturers on here now, come back defending all the modern virtues of the courses they run ... The fact is, at best all we are producing these days are poorly trained domestic installers. It's left to them, to gain the experience they need, to become a well rounded electrician

 

[malcolmsanford]

Malcolm,

It even seems that these so-called lecturers are teaching students to favour radial circuits over RFCs !!! It's not going to be long, if that continues, that the sparks of tomorrow will be gasping in despair at the thought of having to fault find a ring circuit let alone test one!!

I think the whole curriculum of student training, needs a good kick up the arse. Just wait and see all the lecturers on here now, come back defending all the modern virtues of the courses they run ... The fact is, at best all we are producing these days are poorly trained domestic installers. It's left to them, to gain the experience they need, to become a well rounded electrician

I think mate that is another of those nails hit firmly on the head there.

I have to say working overseas for a number of years I have gotten out of the RFC way of thinking, but I personally feel that in many cases it is a viable and a best option.

As you say the trouble with RFC is that it is much more complicated when designing it and testing it, than a bog standard radial. The rule of thumb methods of finding the cable Iz by multiplying the protection device by 0.67, working out Volt Drop and loading the ring, will as you say be a thing of the past, much the same way as MICC is.

I suspect your right tutors/training centres will say it is "development" and "modernizing" of the industry and I suppose it is, but for me still a shame.

 

[i=p/u]

lecutures get a sylabus to follow, thats it.. so do you not think you should blame the iet, top of the shot

 

[Engineer54]

Nothing to do with the IET, but it has everything to do with the lecturers and promoting their own prejudices especially when they are factually and/or fundamentally Wrong!!

We have one lecturer here, that has openly stated that he guides his students away from RFC when providing socket circuits!!! Probably also tells them they can't use a SWA armouring as a CPC too... If these so-called lecturers can't be constructive in the advice they give to there students, then best keep their ill founded opinions to themselves and not burden the students to perpetuate them

 

[moosey86]

I kind of skipped pages 2-12 but if all this hype about using a seperate earth is becoming so much more common, why would buying 5 core SWA not become more common instead of running a seperate earth?

 

[ZsElectric]

I recently found an swa used in this way to a garage, personally in such a zone I would never try to use the sheathing and so installed a rod to earth the satellite box, maybe I dont like to cut corners but then I never take chances just for an easy life

 

[Engineer54]

I recently found an swa used in this way to a garage, personally in such a zone I would never try to use the sheathing and so installed a rod to earth the satellite box, maybe I dont like to cut corners but then I never take chances just for an easy life

So you think a rod is better than a TN system earth do you?? .....Then your a fool !!!
The mind just has to boggle at some of the completly daft an ill informed statements such
as this one.

 

[Guest123]

I recently found an swa used in this way to a garage, personally in such a zone I would never try to use the sheathing and so installed a rod to earth the satellite box, maybe I dont like to cut corners but then I never take chances just for an easy life

Perhaps you'd care to elaborate on what corners are being cut & what chances are being taken by using the knowledge we glean over the years coupled with the training we received, to establish the suitability of a particular material for a particular application???

Not doing something because you 'dont like it' (or dont know any better), then claiming those that do are 'cutting corners' & 'taking chances' is nonsense frankly.

You'll also have to enlighten me on how an Ra of 100-200ohms (probably), is better than a Zs of around 0.5-0.7ohms......

 

[Edd]

In respect to the above posts,, I never take the earth from a property out to an external area, garage shed etc. even though as you say a good Zs from a TN system is a lot better than a high Zs on a TT.. the taking of one earth potential ( the house) to an external area such as the garage can cause (and I have seen it) a potential diffrence..

my main aim when wireing to out buildings is keeping any fault current/ voltage below 50v and appropreate disconection times. Ive seen lost neutrals on PME systems where outhouse neutrals and earths have become live to the surounding earth... would hate to step out that hot tub bare foot onto tera firma.. but hey thats me.. and I know this argument has been done to death, but ive seen the consequences of taking earths from diffrent areas and felt the potential diffrence!!!! :rolleyes4:

im not starting an argument... its just what i feel,, and as long as we are safe and follow the regs,, then we all win!!

 

[Guest123]

would hate to step out that hot tub bare foot onto tera firma..

Well, this is where the training & experience I mentioned earlier comes into play!!!

 

[Edd]

Well, this is where the training & experience I mentioned earlier comes into play!!!

yep too right,, but too date,, with my training and experience, ive never been able to predict the failing of a neutral on a pme system,, if i could i would be doing other things .. "joking please dont rip into me"

 

[Guest123]

I never 'rip in' to anyone.:15:


I just get a bit wobbly when a blanket statement is made on a topic & the only reason being that someone doesn't like doing it the other way.


Obviously there are a number of situations where certain methods of doing things aren't appropriate, but to tar all with the same brush without any thought is a bit blind IMO.

This is almost turning into an extending pme thread (:wacko, we best leave it there I think.