Time to call it a day

[hightower]

In what situation is it the best solution? (Or even a good solution for that matter.)

Well I'd argue that it is well suited in the environment I was in today. An old club with voids all over the place. They don't want conduit/trunking running on the surface everywhere, and it would have been impossible to install conduit/trunking in the void as a retrofit. Being able to rod T+E in the voids allows for progress to be made.

 

[Risteard]

I have used it, if mechanical protected ie metal trunking etc, no problem. Easy to use in commercial refurbs .

So why wouldn't you use singles in a containment system like that mentioned?

Also the cpc size is often likely to be unsuitable for the fault levels encountered in non-domestic installations.

 

[Risteard]

Well I'd argue that it is well suited in the environment I was in today. An old club with voids all over the place. They don't want conduit/trunking running on the surface everywhere, and it would have been impossible to install conduit/trunking in the void as a retrofit. Being able to rod T+E in the voids allows for progress to be made.

Why not use something like Hi-Tuff then with the same csa (and insulated) cpc as the live conductors. I presume you have allowed for non-combustible supports for the wiring system and tried to prevent acrid smoke in escape routes?

 

[7029 dave]

So why wouldn't you use singles in a containment system like that mentioned?

Also the cpc size is often likely to be unsuitable for the fault levels encountered in non-domestic installations.

So why wouldn't you use singles in a containment system like that mentioned?


Simply because it was not a full containment system. Using voids in ceiling, and stud work.

 

[westward10]

So why wouldn't you use singles in a containment system like that mentioned?

Also the cpc size is often likely to be unsuitable for the fault levels encountered in non-domestic installations.

I have never read so much twaddle in all my life. Fault levels in commercial are often similar to domestic with the same type of circuit protection. What Standards do you refer to, give us some numbers.

 

[Risteard]

Fault levels in commercial are often similar to domestic with the same type of circuit protection.

And they are often much greater. If you look at the cable standards you will see that they are designed for domestic installations. You can claim that T&E in non-domestic installations is good practice all you want but it says more about you than me if you think that. It is frankly an abhorrent practice which only occurs because it is a cheap way of doing things - not because it is a good way.

 

[Ian1981]

And they are often much greater. If you look at the cable standards you will see that they are designed for domestic installations. You can claim that T&E in non-domestic installations is good practice all you want but it says more about you than me if you think that. It is frankly an abhorrent practice which only occurs because it is a cheap way of doing things - not because it is a good way.

An example would be dado trunking for a computer suite.
Where does it state and why not use twin and earth cables if seen fit.
Plenty of room in 100x 75mm trunking , capacity not exceeded to say you have to install singles is absurd

 

[Risteard]

An example would be dado trunking for a computer suite.
Where does it state and why not use twin and earth cables if seen fit.
Plenty of room in 100x 75mm trunking , capacity not exceeded to say you have to install singles is absurd

Trunking is designed for singles - not for T&E. And in Dado T&E is so inflexible as to be completely unsuitable.

 

[7029 dave]

Trunking is designed for singles - not for T&E. And in Dado T&E is so inflexible as to be completely unsuitable.

I agree on that.

 

[kingeri]

Trunking is designed for singles - not for T&E. And in Dado T&E is so inflexible as to be completely unsuitable.

Also there is no reference method B for t&e suggesting that it was not conceived originally that people would start putting it in conduit etc.

 

[Ian1981]

Trunking is designed for singles - not for T&E. And in Dado T&E is so inflexible as to be completely unsuitable.

So you wouldn't use trunking in domestic applications like trunking a twin and earth cable to a db for instance adding a circuit or if db is in a garage cables enter db on bare block work?

 

[Risteard]

Also there is no reference method B for t&e suggesting that it was not conceived originally that people would start putting it in conduit etc.

Precisely - again this is because it is not intended for non-domestic installation methods.

 

[Risteard]

So you wouldn't use trunking in domestic applications like trunking a twin and earth cable to a db for instance adding a circuit or if db is in a garage cables enter db on bare block work?

Mini-trunking is completely different to a proper metallic trunking system or dado trunking. So it's a bit of a silly point to make. There it is simply being used for tidiness and not as a containment system.

 

[Ian1981]

Also there is no reference method B for t&e suggesting that it was not conceived originally that people would start putting it in conduit etc.

There's a method B for cables 70 degree operational temp tables.
Sheathed cables

 

[Ian1981]

Mini-trunking is completely different to a proper metallic trunking system or dado trunking. So it's a bit of a silly point to make. There it is simply being used for tidiness and not as a containment system.

50 x 50 trunking is not mini trunking where the db is installed in say a garage on block work and the cables are installed in the said trunking entering the db.
Ref method B

 

[Risteard]

50 x 50 trunking is not mini trunking where the db is installed in say a garage on block work and the cables are installed in the said trunking entering the db.
Ref method B

Again, you are not talking about a containment system but merely a way of keeping the cables tidy. A containment system is completely enclosed for a start.

 

[Ian1981]

Again, you are not talking about a containment system but merely a way of keeping the cables tidy. A containment system is completely enclosed for a start.

Look to say you would try and ram in twin and earth cables in say 20mm galv conduit on a conduit system is not the correct way however to say twin earth cables can't be installed in all commercial containment if installed correctly I don't agree with

 

[Rpa07]

@Sparkhe did I mention that we bicker a lot and forget all about the original post! Electricians - like housewives sometimes! No offence @Midwest!

 

[Darkwood]

Has no one brought up the issue that the loads are in excess of 2 Kw and require independant circuits, it sounds like the OP fed a 2way board from a 32amp mcb with 2,5cable now if that was a ringmain tap off then he has breached the regulation in the fact that the designed loads are in excess of 2kw and would need their own individual circuit.
If the OP has wired it direct from its own 32amp mcb then I still think the installation is in poor design, it's been stated that these toasters are rated at 16amp so this should be the designed load value not a clamped value, we do not have enough info on the toasters to comment any further but they could be power regulated to control the heat better or the voltage to the premises may have been lower than normal that day due to network loading and VD, what would happen if that was rectified in the future thus these toasters may draw more current and possible overload the cable.

You cannot even use the fixed load regulation to allow a higher rated OCPD than the cable because the cable does not meet the specified ampage of the toasters combined so I have to agree here its a poorly design and could become dangerous, regardless of still been on the 16th edition here, this shouldn't have been design this way even if your on the 15th edition on paper.

 

[Sparkhe]

Has no one brought up the issue that the loads are in excess of 2 Kw and require independant circuits, it sounds like the OP fed a 2way board from a 32amp mcb with 2,5cable now if that was a ringmain tap off then he has breached the regulation in the fact that the designed loads are in excess of 2kw and would need their own individual circuit.
If the OP has wired it direct from its own 32amp mcb then I still think the installation is in poor design, it's been stated that these toasters are rated at 16amp so this should be the designed load value not a clamped value, we do not have enough info on the toasters to comment any further but they could be power regulated to control the heat better or the voltage to the premises may have been lower than normal that day due to network loading and VD, what would happen if that was rectified in the future thus these toasters may draw more current and possible overload the cable.

You cannot even use the fixed load regulation to allow a higher rated OCPD than the cable because the cable does not meet the specified ampage of the toasters combined so I have to agree here its a poorly design and could become dangerous, regardless of still been on the 16th edition here, this shouldn't have been design this way even if your on the 15th edition on paper.

Hi darkwood I see were you are coming from sounds about right. But I did not come off a ring main as that would have been stupid, it was from a 32amp mcb on a fuse board . So thanks for the input.

 

[davesparks]

Sorry I call it commercial as it's 9 buildings not a factory. Yes I hate predict text. 32amp breaker supplying a small 2 way board and 16a mcbs in turn each mcb supplying a toaster.
Sorry for the misunderstanding.
Have the regulations changed that much ?

Changed from when? I don't think 2.5 has ever been given a current rating in excess of 32A

 

[Des 56]

Changed from when? I don't think 2.5 has ever been given a current rating in excess of 32A

Not quite but the equivalent was mighty close
7/.036 at 28 amps was once regarded as ideal on 30amp fuse wire

 

[westward10]

Has no one brought up the issue that the loads are in excess of 2 Kw and require independant circuits, it sounds like the OP fed a 2way board from a 32amp mcb with 2,5cable now if that was a ringmain tap off then he has breached the regulation in the fact that the designed loads are in excess of 2kw and would need their own individual circuit.
If the OP has wired it direct from its own 32amp mcb then I still think the installation is in poor design, it's been stated that these toasters are rated at 16amp so this should be the designed load value not a clamped value, we do not have enough info on the toasters to comment any further but they could be power regulated to control the heat better or the voltage to the premises may have been lower than normal that day due to network loading and VD, what would happen if that was rectified in the future thus these toasters may draw more current and possible overload the cable.

You cannot even use the fixed load regulation to allow a higher rated OCPD than the cable because the cable does not meet the specified ampage of the toasters combined so I have to agree here its a poorly design and could become dangerous, regardless of still been on the 16th edition here, this shouldn't have been design this way even if your on the 15th edition on paper.

See #14.

 

[westward10]

And they are often much greater. If you look at the cable standards you will see that they are designed for domestic installations. You can claim that T&E in non-domestic installations is good practice all you want but it says more about you than me if you think that. It is frankly an abhorrent practice which only occurs because it is a cheap way of doing things - not because it is a good way.

I don't recall me stating it is good practice nor how I go about installing commercial installations. Still waiting where any Standard states it is not suitable commercial installations. Not interested in examples but fact backing up your original statement.

 

[Darkwood]

See #14.

I was specifically refering to the discussion about it possibly been on a ring (which we know is not the case now), no one seemed to bring up the fact it would still contravene regulations due to the load size been >2kw but the discussion went on for a while about the legality of spuring off the ring while ignoring the fact it still wouldn't comply.
I did clock it had been mentioned about the OCPD been larger than the cable, on that point I was just re-enforcing it, I should have been clearer possible in my reply.

 

[Diddy]

Op your 32a was too big a breaker/fuse always has been always will be. Best just put hands up and fess up to a B up rather than jacking it all in after 30 years. Secondly go and do your 17th there really is no need for you NOT to have done it. Your employer should pay for this if you are not self employed.
On to the T+E argument - personal opinions are not law nor are they regulations. No matter how many times you repeat them they still are not either of the above. There must be tens of thousands of commercial installations in the UK today that are predominantly wired in "normal" T+E. As far as I am aware they are breaking no regulations nor laws nor rules.
Yes it would be fantastic if the whole world was wired in micc....In my humble opinion one of the best cables out there in terms of protection ect....But then in the real world............
I can only assume some people either do not ever do commercial or are working for a company in a little cocoon who never do commercial shop fit-outs ect. It's very east to say that this isn't right or that isn't good practice until a client states well you can price for this job that may keep your guys in work for 3 months but it's all in T+E...decision time big lad T+E or JSA for you and your guys ? Especially as T+E is suitable and perfectly legal for the job.....Your call lol.

 

[Risteard]

Still waiting where any Standard states it is not suitable commercial installations.

I didn't say that they state it is unsuitable for commercial applications - I said that they state that it is intended for domestic applications.

 

[Risteard]

I can only assume some people either do not ever do commercial or are working for a company in a little cocoon who never do commercial shop fit-outs ect.

I do a lot of commercial including shopfits (often as a subbie), and am happy to say that it is almost always steel trunking with either PVC or steel conduit drops and wired in LS0H singles (6491B) throughout! I can count on one hand the amount of times I have been engaged in non-domestic T&E jobs and I thank God for that given the apparent frequency of such jobs in England!

There is no point whatsoever in pretending that T&E has been designed for anything other than house bashing.

 

[Ian1981]

I do a lot of commercial including shopfits (often as a subbie), and am happy to say that it is almost always steel trunking with either PVC or steel conduit drops and wired in LS0H singles (6491B) throughout! I can count on one hand the amount of times I have been engaged in non-domestic T&E jobs and I thank God for that given the apparent frequency of such jobs in England!

There is no point whatsoever in pretending that T&E has been designed for anything other than house bashing.

Twin and earth has the advantages of being a wiring system contained within its self(sheathed) and is ideal for wiring under ceiling/floor voids, installing through walls without added mechanical protection as long as it's installed correctly. Singles as we know need containment through out their length.
Both wiring systems have a place in commercial installations and are used in such a manner.
Don't see what the big deal is really!

 

[Ian1981]

Also there is no reference method B for t&e suggesting that it was not conceived originally that people would start putting it in conduit etc.

Table 4D5- 70 degree twin earth cables
Ref method A enclosed in CONDUIT in an insulated wall
Ref b is trunking, conduit etc on a wall

 

[Dave OCD]

Changed from when? I don't think 2.5 has ever been given a current rating in excess of 32A

Not relevant to this thread but I'm pretty sure 2.5 M.I. will handle that, possibly a bit more.

 

[Pete999]

Not quite but the equivalent was mighty close
7/.036 at 28 amps was once regarded as ideal on 30amp fuse wire

You mean 1/036 of course?

 

[westward10]

Not relevant to this thread but I'm pretty sure 2.5 M.I. will handle that, possibly a bit more.

2H2.5 will.

 

[Des 56]

You mean 1/036 of course?

Of course not,I meant what I wrote

 

[Andy-1960]

I beg to differ.2.5 cable can take a max of 27 amps if clipped direct.23amps in a wall or 21 amps above a plasterboard ceiling with insulation.Putting a 2.5 on anything bigger than a 20amp breaker would be madness.Personally i would put a 16amp breaker feeding it.If you wish to back up your claim then please quote the relevant BS7671 number.

Reg 433.1.5 ?