Where Can You Use 90°C Insulated Cable?

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Күн бұрын

In this video, we discuss XLPE insulation, and how it provides a higher operating temperature of 90°C compared to PVC, which has an operating temperature of 70°C.
Electricity running through a conductor causes heat, and the more current flowing through it, the hotter it gets. Because electricity is dangerous, we cover our conductors with insulation - made from various materials such as PVC, XLPE, silicon, and even minerals like magnesium oxide.
However, these insulators have their limits and start to degrade or melt when subjected to temperatures beyond a certain point. For instance, PVC starts melting at temperatures higher than 70°C, while XLPE can withstand up to 90°C.
In this video, you will learn the uses for XLPE cable, the importance of ensuring that your electrical equipment is rated to operate at the same temperature as your installed cable and a method to make use of the extra current carrying capacity of 90°C cable to save you money.
Reviewed - the Wago Quickstrip Vario 👉 • The Wago Quickstrip Va...
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Time Stamps ⏱
00:00 Where can you use 90°C insulated cable
00:47 Lets refresh ourselves on the basics
01:51 Where do you come across XLPE?
02:00 information on how much current 90°C insulated cables can handle.
03:42 Max operating temperatures also apply to conductors in switchgear and wiring accessories
04:46 You have to check if the electrical equipment you're connecting to is rated at the same temperature
05:28 The 70°C Limit is met if the live conductor size is chosen based on the current rating for 70°C cables of similar construction
06:15 We can make use of the extra current carrying capacity of 90°C cable
07:10 This can be a cheaper installation option
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#cables #electricians #electricalinstallation

Пікірлер: 59

@NickToland 8 ай бұрын

Unbelieveable how much I learn from you guys.

@johnlloyd3377 8 ай бұрын

Another interesting topic with a great explanation of the regulations by Joe. The topic of heat is not given enough prominence in electrical design with many switchgear enclosures with no obvious means of dissipating the heat emitting by the electric equipment enclosed. I believe this has become of greater significance in recent times with the design and implementation of solar powered installations where outdoor equipment is subject to solar gain leading to equipment with high surface temperatures.

@efixx 8 ай бұрын

Thanks very much! 😊

@chorleycake7942 8 ай бұрын

Nice explanation, I have seen sparks install smaller XPLE cables without any consideration of the switchgear and equipment ratings they are connecting the cable to. Some of them thought they were next level geniuses because they had managed to downsize the cables.

@andysims4906 8 ай бұрын

No cable should be operating near there limit anyway. Bad design if it is .

@atlasz911 8 ай бұрын

I'm not a top electrician but for really long distances, where this would actually save some money I prefer to rather upscale and lower the resistance and losses. A few % on the cable price adds little to the final costs and nobody knows, what else will be connected there in 5-6 years.

@efixx 8 ай бұрын

Very fair point. 👍

@mgsp5871 8 ай бұрын

central heating equipment often requests cables for higher temperatures despite carrying only some mA. The circulating water may get hotter than 70° and so does the pump.

@CommercialGasEngineerVideos 8 ай бұрын

Thanks for sharing

@BenWiggins101 8 ай бұрын

Great topic and well lead 👍⚡

@mathiasjacobsen3355 8 ай бұрын

One thing to consider. A 90 C cable can handle a short between line and neutral for a longer time compared to 70 c cable, of the same size. The same size mcb for 90 c cable might not be suitible for a 70 c cable, depending of type mcb b-c or d, cable length(resistance), since higher resistance reduces the short current necesscary to trip the breaker/mcb, before cable reaches dangerous temperatures. I am not familiar with Uk regulations, but a 90 c single cable (small lengths like 0,5 m - 1 m) is often used in Denmark, in large switchgear/distribution boards, between copper rails and circuit breakers (mcb), due to the cables higher operating temp. at 90 c.

@TheAviation101 8 ай бұрын

Some cables in UK consumer units are silicone and rated for much higher than 90c, 180c/200c but they're still sized as though they're 70c. The MCB already runs hot, no point using overly thin wires to make it run even hotter.

@soundspark 8 ай бұрын

Of course isn't the intent however to be tolerant to higher ambient temperatures?

@abdulseaforth6930 8 ай бұрын

Thank you thank you thank you.

@efixx 8 ай бұрын

No, no, thank you!

@tarassu 8 ай бұрын

Don't forget that even though cable can get hotter, it does so because is has higher voltage drop. Keep in mind if you run the cable for more than 10 meters.

@efixx 8 ай бұрын

Yes, lots of factors impact on cable selection. 👍

@abdulseaforth6930 8 ай бұрын

I twist at the tip to give a good chance of all the strands entering the ferrule.

@efixx 8 ай бұрын

Top tip!

@TheManLab7 8 ай бұрын

For the vast majority of the time. I only check the regs to see what size cable is required and like most decent sparks. We can guess the cable n were right the vast majority of the time, but it's always nice to double check.

@efixx 8 ай бұрын

Yur, always good to go through the proper design process. 👍

@darrenjeffes7030 8 ай бұрын

Balls every time I watch one of these I realise I've deviated from the regs somehow

@TheChipmunk2008 8 ай бұрын

That's good tho, it shows you care about the regs... :)

@kletops46 8 ай бұрын

Would you require to install a protective device in the DB's if you change conductor size in the DB's ?

@efixx 8 ай бұрын

Check out this video 👉kzfaq.info/get/bejne/hN2IbNKGq7i7gIk.htmlsi=m8vg8Px34p0Ll5al

@JussiPeltola 8 ай бұрын

Realistically, cables in a bundle or penetrating through insulation may reach 90 and once you stripped and terminated the ends with lots of air between the cores it is unlikely to reach 60. The only case where switchgear would really overheat is if you size runs based on the 90deg capacity table for single conductors inside a board, actually making them reach 90 inside a board. If you follow the northern European rules, it is usually one wall penetration that causes use of 2.5 for 16A and 10mm2 for 32A, while 6mm2 for 32A would be fine inside a panel or clipped on a wall as is 1.5 for 16A. Thick, modern insulated walls with bundles of cables going thru would require 4mm2 for 16A, and since 4mm2 is out of print, it would have to be bumped to 6mm2 for 16A. This rule is usually just ignored, but certainly 90deg 2.5mm2 is just fine for such cases, once you separate the conductors you can barely detect any heat and no uninformed party will later up-size the breaker from 16 since the wire is 2.5, so it is actually safer to use 90deg wire than up-size the copper.

@JussiPeltola 8 ай бұрын

In fact I would not be surprised if a 75deg single on the other end of your breaker may be allowed to carry more current than a multicore cable going through a wall or bundled with others but I am too lazy to check the UK derating tables. Let alone a breaker where both sides connect to 75deg single wires inside a board, sized to actually reach 75. It is quite certainly going to run hotter than a breaker feeding a 90 multicore cable unless the multicore cable runs unbundled and with no other reasons for derating the whole way, so it can reach anywhere near 90 at the ends.

@TheAviation101 8 ай бұрын

Yes singles are rated higher But you can't just say once the insulation is stripped back that you suddenly drop the conductor temp by 20c. Copper is a good conductor of heat so if the cable is coming through an insulated wall and suddenly into an enclosure, the stripped back section will be wicking up heat away from the wall and still run too hot. Also for consumer units, the air temperature is very high (due to the inherent heating element/ bimetallic strip inside each mcb/ rcbo) and should be treated as a sealed environment with no airflow other than natural convection. For socket outlets you have to consider that the plugs will have fuses and some contact resistance which also generate heat. The cooling effect is not great at all.

@roystevenson1375 7 ай бұрын

4mm out of print??...tons of it on my job

@JussiPeltola 7 ай бұрын

@@roystevenson1375 In the Nordic countries you may find 4mm2 with old colors, and you can get it on back order from some manufacturers in the new colors after weird looks from the distributor. Probably takes a while to arrive. If you find 4mm2 with the modern colors actually used in some installation here I would try to fill a lottery ticket on that day. The cooker used to be 4mm2 20A in the 70s and now it is 3ph 2.5 fused 16A or 1ph 6mm2 fused 25A.

@roystevenson1375 7 ай бұрын

@@JussiPeltola what were the old Danish colours?

@glenwoofit 8 ай бұрын

But surely the joint that can reach 90°C is connected to a cable that will melt at 70°C so heat conducted from joint will damage the insulation on the 70°C cable.

@TheAviation101 8 ай бұрын

You should use thick 90c cable of sufficient length such that it drops by 20c by the time it reaches the 70c termination point.

@jonathanbuzzard1376 8 ай бұрын

Would it not be a use of 90°C cable where you derating it for part of the run? Looking at the tables an example would be 90°C cable SWA underground to an outbuilding/garage. If you put it on a 40A breaker then you can manage it with 4mm XLPE SWA but would have needed 6mm PVC as 4mm is only rated for 37A when direct in ground, but fine at 41A in the "free air" of the consumer unit?

@TheAviation101 8 ай бұрын

There's insufficient length within the consumer unit to drop the temperature, also consumer units run hot from all the MCBs inside. You need about 1m of a free air run before the CU to be acceptable I would say such as perforated cable tray.

@dansheppard2965 8 ай бұрын

This got me wondering how mineral-insulated copes with overcurrent. I guess the copper melts first!

@efixx 8 ай бұрын

There's the danger caused by a hot cable to the fabric of the building and people touching it to take into account as well. 👍

@geoffgeoff143 8 ай бұрын

V90 cable is now almost standard.

@aardwolf21 8 ай бұрын

If converting from 70 degree cable to 90 degree cable in a JB, doesn't just the fact that there is 70 degree cable in the JB mean that you can't have cable that could be at a higher temperature in that JB? You would need 2 x JB, one to go from 90 rated, to 90 rated but larger cross section so not above 70 rated limit, into a second JB to go from the underated 90 to 70 rated.

@TheAviation101 8 ай бұрын

There's no need for the second JB. After a sufficient length of the thicker 90 cable and it has cooled to 70c, then it's now safe to enter the CU and the switchgear. By that point it's 90c cable operating at 70c.

@aardwolf21 8 ай бұрын

@@TheAviation101 Good point, so rather than as the diagram at 6.50 or so shows converting 90 rated to 70 rated at the JB, you actually need to convert 90 rated to derated 90 to the end termination.

@TheAviation101 8 ай бұрын

@@aardwolf21 yes because there will be a temperature gradient between 90 on one end and 70 on the other. Since copper is a good conductor, I would say at least 1m or ideally 2m of length for this.

@Superkev001 8 ай бұрын

In my 35 years, I have only really seen a cable burnt due to, say, someone wiring a shower in 1.0mm. Never felt cables warm in normal operation apart from immersion flex

@TheAviation101 8 ай бұрын

because these temperature ratings are for the internal copper temperature. Since the insulation + sheath is really bad at conducting heat, the copper temperature is much higher than what the outer sheath feels like. A 90c armoured cable operating at 90c will not burn you when you hold the outer sheath.

@TheChipmunk2008 8 ай бұрын

I hadn't till recently (except on multi hundred amp cable tray installs when i was a yoof), but have felt a 4.0mm SWA get noticably warm when charging a car... the full 32A for hours at a time has effects

@roystevenson1375 7 ай бұрын

Sheltered life?

@goober-ll1wx 8 ай бұрын

But does current really "flow" through a conductor.......🤔

@davidfaraday7963 8 ай бұрын

Whether it does or not it causes the conductor to heat up.

@goober-ll1wx 8 ай бұрын

@@davidfaraday7963 if it doesn't what's causing the heating.... 🤔🤣

@davidfaraday7963 8 ай бұрын

@@goober-ll1wx Why are you asking me? You were the one who posed the original question

@goober-ll1wx 8 ай бұрын

@@davidfaraday7963 it was a rhetorical question hence the no question mark 🙄

@Irilia_neko 8 ай бұрын

Just use polyethylene insulation for the coble, it's recyclable, and even non toxic. Tbh more heat = more power lost. So having the polyethylene insulation is actually better if you respect the normal table for 70C because it avoid having a short-circuit if you override the maximum current of the cable

@1971dave 8 ай бұрын

This is why electrics is one of the most boring trades ever known to man, look at my new house the stonework is beautiful, nice skimming you've done there mate, the decorating looks absolutely superb with the new carpet and the furniture, kitchen looks lovely also, brilliant mate but come and look at my 2.5 twin and earth,

@efixx 8 ай бұрын

Pft, form and function both play a part!