95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fuses

[markc17]

Hi all,
I commissioned the renewal of some mains intake equipment at a building that involved a full shut down. The building runs 24/7 and so a shut down is a VERY rare event. Upon completion of the works the contractor informed me that the 95mm 4 core cable feeding the building was being protected by 200 amp fuses. I looked at table 4D4A and this suggests that the maximum currenct carrying capacity for a cable ot this type,running in ducting, is only 169 Amps.
I asked for old records and test results (which are sketchy at best) and it does seem to point at the fact that this was how the install was done from the outset. Periodic results from ten years ago conveniently have the cable size missed out on the results sheet. Unless i am missing something, this would mean i have to recommend they change their fuses to 160 amp ( which would be a virtual impossibility) or upsize the mains incoming cable which is going to be very costly. Before i recommend these works and upset the boat.. am i missing something?

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Forget table 4D4A, and look at the manufactures data for this cable!! It's probably still going to be close to the mark!! Any idea of the maximum demand of the overall load of this buildings equipment??

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Any idea where i would find the information on the cable? as i say the installation is fairly old and information is pretty sketchy. I put a metering pack on the mains of the building for a week and during the day there were peak readings up to 200 amps on the phases, with one even reading as much as 225 during a busy lunch time. If no information is available, surely table 4D4A is what i will have to go by... am amzaed at how much the cable derates being in a ducting. I have to provide the owners with a recommendation....

 

[i=p/u]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

interesting................ id say stick to book, but you could try doing calc out on full.. but what do i know just interested

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

I'd say it's fine, it could potentially carry 260 amps, we would need specific information to be sure.

Exact cable type, a precise description of installation method etc.

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Who here would go by the book, rather than the cables manufacturer themselves?? Remember that all derating factors and installation methods applied to cables, are based on stated full load current of that cable!!

Quite appalled at the lack of understanding here, and the total reliance of taking figures out of tables that are also not being fully understood!!

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Elecsa table actually confirms the rating of 169 Amps as it is a 4 core cable. The switch for the building is fed via main busbars.. 200 amp fuses... then a 30 m run underground up into an intake cupboard to main isolator for building. I can probably see a metre of the cable at each end if i am lucky so am honestly asking how i find out manufacturers information on the cable.. if i cant see anything pointing to manufacturer.. surely then tables must be used.... i would understand if the drop was negligeable.. but 169 amps.. to 200 amps is not...

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Check out a few cable manufactures data, they will generally be pretty much in the same ball park!! Check the insulation too, PVC or XLPE. XLPE insulation tends to be more transparent and thinner than PVC insulation, which will also be much brighter in colour than XLPE!! From only my bad memory, 95mm 4 core SWA, should be capable of supplying in excess of 200A rather than the 169A being banded about just because it's in a 30m duct... but i'll stand to be corrected if wrong!! lol!!

We are talking here of only around 30A, and if this is an original cable, that has been in service for some time and has provided the means of supply to the same loading of this building without any ill effects, then my guess is that it will continue to be adequate. Having said that, if the owner is thinking of extending the loading in the foreseeable future, then a cable upgrade would be a prudent move to make now, while the installation as a whole is being renovated. How come this supply cable has only come to light, at or towards the end of the job, surely this would have been one of the first things to assess before the job started!!

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Not here to stand to correct you my friend, im only going off whats in the book. It states 169A. Pretty sure its not XLPE. As i say, am suprised myself at how much the cabel derates just from being in a duct.
I agree with you that it should have been assessed at the beginning of the job, assumptions were made as the mains are never ever shut down due to servers and other complications with the building as it is never really not in use. To be honest... whether this assessment had been made at the beginning or the end the job would still have had to go ahead as the incoming mains had no means of isolation and was so crowded that a pannel was essential..
The building is adding more and more all the rime in the way of computer rooms etc.. and as i say.. i had a peak reading of 225 amps on a friday.. it lasted for a good minute or three above 200 amps...

 

[Bobster]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Is it showing signs of overheating?

 

[Megavolt]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Stick with cable manufactors every time

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Not here to stand to correct you my friend, im only going off whats in the book. It states 169A. Pretty sure its not XLPE. As i say, am suprised myself at how much the cabel derates just from being in a duct.
I agree with you that it should have been assessed at the beginning of the job, assumptions were made as the mains are never ever shut down due to servers and other complications with the building as it is never really not in use. To be honest... whether this assessment had been made at the beginning or the end the job would still have had to go ahead as the incoming mains had no means of isolation and was so crowded that a pannel was essential..
The building is adding more and more all the rime in the way of computer rooms etc.. and as i say.. i had a peak reading of 225 amps on a friday.. it lasted for a good minute or three above 200 amps...

Mark, you have benn given good advice, your sure ist not XLPE, id be pretty sure it is since the standard has changed requiring it!

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Not here to stand to correct you my friend, im only going off whats in the book. It states 169A. Pretty sure its not XLPE. As i say, am suprised myself at how much the cabel derates just from being in a duct.
I agree with you that it should have been assessed at the beginning of the job, assumptions were made as the mains are never ever shut down due to servers and other complications with the building as it is never really not in use. To be honest... whether this assessment had been made at the beginning or the end the job would still have had to go ahead as the incoming mains had no means of isolation and was so crowded that a pannel was essential..
The building is adding more and more all the rime in the way of computer rooms etc.. and as i say.. i had a peak reading of 225 amps on a friday.. it lasted for a good minute or three above 200 amps...

It's your call, at the end of the day!! Personally i wouldn't derate a 95mm SWA cable down from around 250'ish Amps or so to 169A because it runs in a duct for 20m or 30m!! Why don't you check the two ends of this existing cable for signs of stress, i doubt very much if you'll see any!!

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Mark, you have benn given good advice, your sure ist not XLPE, id be pretty sure it is since the standard has changed requiring it!

Heya Chris, I am not doubting any advise thats for sure.. i appreciate people taking the time to help me out, including yourself. I was given layout drawings this morning which confrims the cable is PVC. Like everyone is suggesting on here.. i am actually in agreement.. there is no signs of stress or overheating.. but the contractor that has carried out the mains change has highlighted the fact that the fuses need to be downsized, and will only sign off from his side of the new isolator and the fixed wire test 5 years ago it seems made a recommendation to do the same thing. the cable derates nearly 100 amps putting it in the ground according to the book.. i am just trying to come up with the best way to advise the client what to do is all..

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

It's your call, at the end of the day!! Personally i wouldn't derate a 95mm SWA cable down from around 250'ish Amps or so to 169A because it runs in a duct for 20m or 30m!! Why don't you check the two ends of this existing cable for signs of stress, i doubt very much if you'll see any!!

Appreciate the advise. I think the derating is over the top too. Theres no stress or overheating. Just figures causing me headaches from a book. If a contractor brings the matter to the clients attention, as another, it appears has done in the past, then it is my job to advise and recoomend a course of action. Am compiling a report containing meter readings for the week.. now just writing covering letter..

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Is it showing signs of overheating?

No Rob.. noth ing to suggest stress..or overheating.. just a few peak times of the day when the amp readings are high (over 200)..and often over the 160 amps to satisfy the table.. problem is that a contractor has recommended a downsizing of fuses recently, as has one in the past. To upgrade the cable would be a huge job so dont want to advise anything rash but the building is obviously pulling more and more as the years go on.

 

[Darkwood]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Im in the thinking the original fuses may have been 160's in a 200amp isolator and probably through ill thinking they were changed to 200 to match the isolator without thought as to why they were 160amp in the first place. Id be inclined to sit down and discuss this with the client and express your concerns the fact your only having occasional peaks >200 amp for a few minutes at most is why you havent seen the 200amp fuses go and why there will be no cable damage as such....... check your time current curves on 200amp fuses?

If the plans are for expansion that will add load to the existing set-up then the existing cable won't be adequate even if it was sized correctly, also to check if additional loading is planned is KVA demands and what allowance you have and what the DNO can spare if any, pointless weighing up for increased supply if there isn't a buffer zone available from the DNO to give you extra without charging you for a new substation.

Your difficulty here is probably knowing who made the cable and without this info you have to adhere to the tabulated values and recommend a derating of the fuse or increase of csa of cable... either way i would note it down because your the last inspection and if anything occurs in the near future like an overload of cable or fuses going im sure the downtime will be costly and having written recommendation that it needs addressing will stop the company chasing you for some kind of compensation.

All companies cry poor when costs are unexpected but if they plan on fitting computer suites then maybe that money needs directing to sorting out the power supply issue.... it can all be done with minimal downtime by digging new trench and running new cable in while existing is still functional the added costs of doing this will normally outweigh the cost of shutdown.

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Im in the thinking the original fuses may have been 160's in a 200amp isolator and probably through ill thinking they were changed to 200 to match the isolator without thought as to why they were 160amp in the first place. Id be inclined to sit down and discuss this with the client and express your concerns the fact your only having occasional peaks >200 amp for a few minutes at most is why you havent seen the 200amp fuses go and why there will be no cable damage as such....... check your time current curves on 200amp fuses?



If the plans are for expansion that will add load to the existing set-up then the existing cable won't be adequate even if it was sized correctly, also to check if additional loading is planned is KVA demands and what allowance you have and what the DNO can spare if any, pointless weighing up for increased supply if there isn't a buffer zone available from the DNO to give you extra without charging you for a new substation.

Your difficulty here is probably knowing who made the cable and without this info you have to adhere to the tabulated values and recommend a derating of the fuse or increase of csa of cable... either way i would note it down because your the last inspection and if anything occurs in the near future like an overload of cable or fuses going im sure the downtime will be costly and having written recommendation that it needs addressing will stop the company chasing you for some kind of compensation.

All companies cry poor when costs are unexpected but if they plan on fitting computer suites then maybe that money needs directing to sorting out the power supply issue.... it can all be done with minimal downtime by digging new trench and running new cable in while existing is still functional the added costs of doing this will normally outweigh the cost of shutdown.

Id wait untill he aquires the relevent information before he does anything, potentially this cable could take upto 260 amp.

 

[Gage]

I agree with darkwood you should be concerned that the 200A fuses haven't blown at 220+ amps sustained for minutes.

Also there's videos on YouTube of 95mm taking 5000 amps only for about 20 minutes but still

 

[Brightspark2]

If you cant get any manufacturers details then you'll have to go from the regs book. If anything happens least your bum will be covered.

You can only advise, just as the last 2 contractors did. Advise them on the options.

Just because it's been ok so far doesnt mean it's going to be ok in the future with expansion.

Remember it's your name on it all the end...:thumbup:

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

What's the overall length of this 95mm 4 core cable?? You've only indicated you have 30m run in ducting, is that roughly the total length or is it much longer than that 30m??

If it's roughly around the 30m mark, it isn't going to be an overly expensive upgrade, especially if you use a parallel supply, using 2 X 25 or 35mm 4 core SWA cables, the later giving you around 325A, which will be more than enough to de-rate to your hearts content for the ducting!! lol!! Also be a lot easier to man handle during the installation....

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Mark, go down and get the BS number and manufacturer of the cable, forget what's being said, the oversheath may well be PVC, I doubt the insulation will be!

What's the length of cable entering and exiting the duct with regard to terminations? How is the duct installed, surrounding material etc, what is the ambient being taken as?.

I've got 263 in a duct at 90 C, even if I run it at 70 C it still greater than 200.

You need to assess the install before anything.

 

[Brightspark2]

I doubt the insulation will be!

Why's that squire?...

Remember this is an old installation...



Also worth remembering if designing the circuit for 90 degree cable then connected equipment needs to be rated at that too...

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Why's that squire?...

Remember this is an old installation...



Also worth remembering if designing the circuit for 90 degree cable then connected equipment needs to be rated at that too...

Old installation, New cable is it not? As I have said, SWA standards have changed.

I'm aware of the 90 C, I've already raised that issue with Mark.

No point going any further until Mark addresses the points I've raised.

 

[LlandrilloSpark]

A good example of this is the CCC of 10mm two core armour , I priced a job on Friday eve , bs7671 states approx 60 Amps , TLC website who use manufacturers Data states over 80A

 

[Spoon]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

especially if you use a parallel supply, using 2 X 25 or 35mm 4 core SWA cables, the later giving you around 325A, which will be more than enough to de-rate to your hearts content for the ducting!!QUOTE]

I may have read this wrong but the rating you have quoted is Reference Method E and what he has is Reference Method D, 115A for 35mm so 230A for parallel cables. If they are installed in the same ducting then you have to de-rate the cable by .75 (cables touching) so you would get 86A or 172A for 2 cables.

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

especially if you use a parallel supply, using 2 X 25 or 35mm 4 core SWA cables, the later giving you around 325A, which will be more than enough to de-rate to your hearts content for the ducting etc!!QUOTE]

I may have read this wrong but the rating you have quoted is Reference Method E and what he has is Reference Method D, 115A for 35mm so 230A for parallel cables. If they are installed in the same ducting then you have to de-rate the cable by .75 (cables touching) so you would get 86A or 172A for 2 cables.

I wasn't comparing ref methods, as i stated, more than enough leeway for any de-rating for duct installation...

They are the same supply cable, be they X 2, X 4 or whatever, you don't de-rate a parallel circuit, de-rating only applies if the cables being de-rated are two different supplies!! Would you de-rate a ring circuit if both legs were run in a conduit/trunking?? lol!!

Depending on any other criteria, i'd be more than happy rating a parallel 35mm supply at or around 280A +. I rarely take much notice of cable ratings in the BGB, i tend to mainly use manufacturers data. But that would be up to the OP and his own experience as to what sort of de-rating factors to apply on any given cable installation etc... Whatever way you go, 2 X 35mm SWA cables are going to fulfill the OPs supply cables requirement....

 

[Spoon]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

They are the same supply cable, be they X 2, X 4 or whatever, you don't de-rate a parallel circuit, de-rating only applies if the cables being de-rated are two different supplies!! Would you de-rate a ring circuit if both legs were run in a conduit/trunking?? lol!!QUOTE]

Isn't the de-rating of grouped cables down to heat dissipation? If there are two cables together then they don't dessipate heat as well if they are apart, so that is why they are de-rated. It doesn't matter if they are for the same circuit or different circuits. Its grouping of multi-core cables.

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Mark, go down and get the BS number and manufacturer of the cable, forget what's being said, the oversheath may well be PVC, I doubt the insulation will be!

What's the length of cable entering and exiting the duct with regard to terminations? How is the duct installed, surrounding material etc, what is the ambient being taken as?.


I've got 263 in a duct at 90 C, even if I run it at 70 C it still greater than 200.

You need to assess the install before anything.

Ok.. spoke with someobody in the know that can assure me the cable has been in 25 years plus... i did find a name on the cable.. says AWCO Electric cable 66/1000V BASEc...(crawling around at the back in the dark) No BS number..Cant find anything on AWCO anywhere.. unless im being stupid.. one meter of cable straight out of ducting set in concrete into 200 Amp switchfuses either end..one (old) MEM 200A HRC..off the busbars at the intake... the other 200A TPS-N Hager Fuse combination switch (New)... in building intake cupboard.

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

If an upgrade is to be looked at.. 2 x parallel 35mm cables will certainly be easier to pull than the 150 or 185 needed to upgrade properly according to 4D4A...lol..not that it will be easy.. the road will have to be dug up.. although we may get away with no hydraulic bending equipment and some elbow grease i guess...!..lol.. i think im going to have to quote similar manufacturers figures.. and the regs... and tell them they are full up and to make future plans based on my recommendadtions.. The place is running like a dinosaur anyway.. full of t8 wingback lights.. convection heating everywhere.. might be able to make a few savings the other way... and keep my arse covered..

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

They are the same supply cable, be they X 2, X 4 or whatever, you don't de-rate a parallel circuit, de-rating only applies if the cables being de-rated are two different supplies!! Would you de-rate a ring circuit if both legs were run in a conduit/trunking?? lol!!QUOTE]

Isn't the de-rating of grouped cables down to heat dissipation? If there are two cables together then they don't dessipate heat as well if they are apart, so that is why they are de-rated. It doesn't matter if they are for the same circuit or different circuits. Its grouping of multi-core cables.

This side of it i will need to look into IF they decide to do something.. which i very much doubt..)

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Depending on any other criteria, i'd be more than happy rating a parallel 35mm supply at or around 280A +. I rarely take much notice of cable ratings in the BGB, i tend to mainly use manufacturers data.....

Ever heard of AWCO? or am barking up the wrong tree

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

They are the same supply cable, be they X 2, X 4 or whatever, you don't de-rate a parallel circuit, de-rating only applies if the cables being de-rated are two different supplies!! Would you de-rate a ring circuit if both legs were run in a conduit/trunking?? lol!!QUOTE]

Isn't the de-rating of grouped cables down to heat dissipation? If there are two cables together then they don't dessipate heat as well if they are apart, so that is why they are de-rated. It doesn't matter if they are for the same circuit or different circuits. Its grouping of multi-core cables.

No it doesn't work like that!! The 2 or more cables of a parallel circuit are equally sharring a single point load, so it's a single circuit!! In other words it is considered as a SINGLE cable, not multible cables supplying different loads etc. As i said above, would you actually de-rate a ring circuit contained in a suitably sized conduit or other containment??

 

[Gage]

In debating whether people know the difference between series and parallel

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

If an upgrade is to be looked at.. 2 x parallel 35mm cables will certainly be easier to pull than the 150 or 185 needed to upgrade properly according to 4D4A...lol..not that it will be easy.. the road will have to be dug up.. although we may get away with no hydraulic bending equipment and some elbow grease i guess...!..lol.. i think im going to have to quote similar manufacturers figures.. and the regs... and tell them they are full up and to make future plans based on my recommendadtions.. The place is running like a dinosaur anyway.. full of t8 wingback lights.. convection heating everywhere.. might be able to make a few savings the other way... and keep my arse covered..

That's just how ridiculous some of these cable and de-rating tables can end up, ...with totally silly cable sizes!! Who in their right mind would install a 150 or 185mm cable to satisfy a 200A to 225A supply requirement??

Thought you said this cable was in a duct, why would you need to dig the road up for god's sake??

 

[johnboy6083]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

You need to take a look at ERA report 69.30

this has cable sizes for sustained and cyclic loads. It's one of the methods that DNO's use to size their cables.

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

You need to take a look at ERA report 69.30

this has cable sizes for sustained and cyclic loads. It's one of the methods that DNO's use to size their cables.

Have you got a link to this report??

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Ok.. spoke with someobody in the know that can assure me the cable has been in 25 years plus... i did find a name on the cable.. says AWCO Electric cable 66/1000V BASEc...(crawling around at the back in the dark) No BS number..Cant find anything on AWCO anywhere.. unless im being stupid.. one meter of cable straight out of ducting set in concrete into 200 Amp switchfuses either end..one (old) MEM 200A HRC..off the busbars at the intake... the other 200A TPS-N Hager Fuse combination switch (New)... in building intake cupboard.

Sorry Mark, misunderstood, i thought you had replaced the mains like for like lol for some reason.

 

[Spoon]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

No it doesn't work like that!! The 2 or more cables of a parallel circuit are equally sharring a single point load, so it's a single circuit!! In other words it is considered as a SINGLE cable, not multible cables supplying different loads etc. As i said above, would you actually de-rate a ring circuit contained in a suitably sized conduit or other containment??

Ok, (example 1) so we have a circuit taking 200A run in conduit. The intention is to use 2 cables, each taking 100A. Each producing heat.
Lets just say we also have 2 additional circuits (example 2) each using 100A, supplied with two cables in a ducting. (different ducting to example 1.)
You are saying that the re-rating factor applies to example 2 but not to example 1? How does that work?

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

That's just how ridiculous some of these cable and de-rating tables can end up, ...with totally silly cable sizes!! Who in their right mind would install a 150 or 185mm cable to satisfy a 200A to 225A supply requirement??

Thought you said this cable was in a duct, why would you need to dig the road up for god's sake??

It does enter the building in a duct...Im trying to explain the installation without EVERY detail.. but that duct goes out under the floor... a meter down the side of a buildingoutside into a duct in the road.. then around multiple bends with no access panels of any type..There are no draws in.. from my experience.. pulling any sort of heavy duty armoured around corners is tough.. i dont have any groundworks drawings or a CAT scanner to hand...lol... so i think my observations are a fair assessment.. but still..

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Sorry Mark, misunderstood, i thought you had replaced the mains like for like lol for some reason.

No worries Chris.. to be honest this has been a good learning curve for me.. thanks for your help.

 

[MDJ]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Ok, (example 1) so we have a circuit taking 200A run in conduit.

Bloody hell that must be a big conduit??

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

You need to take a look at ERA report 69.30

this has cable sizes for sustained and cyclic loads. It's one of the methods that DNO's use to size their cables.

will do.. thank you

 

[Stroppy]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Also there's videos on YouTube of 95mm taking 5000 amps only for about 20 minutes but still

Found this: 5000 Amp Fuse + Tools Melt With High Current - YouTube Yikes!!! I bet their mum isn't going to be pleased with the carpet.

(Disclaimer: contains a very rude word)

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Anyone know where i can pull some manufactureres data for a cable like this.. one rpe XLPE.. every site i look at seems to be the latter.. or if anyone has heard of AWCO?

 

[Chr!s]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Ever heard of AWCO? or am barking up the wrong tree

Aluminium wire and cable co, good chance this is a Soidal Aluminium cable?

 

[Brightspark2]

Ahh the plot thickens...

 

[johnboy6083]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Have you got a link to this report??

Unfortunately no. If anyone does have access to this, then I would be happy to have a copy.

ive tried looking for this myself, and can't get it anywhere.

 

[Engineer54]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Ok, (example 1) so we have a circuit taking 200A run in conduit. The intention is to use 2 cables, each taking 100A. Each producing heat.
Lets just say we also have 2 additional circuits (example 2) each using 100A, supplied with two cables in a ducting. (different ducting to example 1.)
You are saying that the re-rating factor applies to example 2 but not to example 1? How does that work?

In simplistic terms Yes, the parallel circuit ensures equal current carrying between the two conductors, (and are considered as a Single cable), whereas the two separate circuits that are supplying different loads will not. The cable grouping de-rating table(s) in the BGB are based on the cables carrying the full load current being present, on each of the grouped cables/conductors, when in the real world that is almost never the case, and why you always end up with over sized cables!!...

 

[markc17]

Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus

Aluminium wire and cable co, good chance this is a Soidal Aluminium cable?

Im sure one of the previous tests (of which i only have the results for one...or this fixed wire test done in August would have said so.. definately says copper on the sheet...) Gulp.. ha.. i certainly hope so or the cable derates down even more! Must admit ive never worked with aluminium cable.. am hoping AWCO made copper SWA too...