Oval conduit fill sizing

[tvrulesme]

Running some cables and fitting some back boxes to save some money in preparation for an electrician to do a 1st fix. Just wondering if there is a simple table available to show what size cable(s) will fit into oval conduit?

Specifically 2 x 6mm2 T+E cables (induction hob and oven) and 2 x 4mm2 T+E (socket radial)

Oval conduit comes in 13,16,20,25,32 and 38mm sizes. Which of those sizes will fit the 2 x cables for 6mm and 4mm respectively?

 

[Deleted account]

As an electrician I used to allow the customer to do the chasing on some rewires, however it rarely worked as the chases where either not deep, or un evenly chased, would go off on one and be outside zones.
I would end up redoing the chases. Thus spending more time than was budgeted for.

so my advice to you is chase deeper than you need and keep it clean, even and straight.

chasing is hard work and takes years of practice to get it right. It is a skill in its own right.

I stopped letting my customers try to save money.

as for a table of sizes. Ask your electrician. He is the one who is specifying sizes and the design. No one else can do this for you other than the designer who is going to sign the work off.

 

[tvrulesme]

As an electrician I used to allow the customer to do the chasing on some rewires, however it rarely worked as the chases where either not deep, or un evenly chased, would go off on one and be outside zones.
I would end up redoing the chases. Thus spending more time than was budgeted for.

so my advice to you is chase deeper than you need and keep it clean, even and straight.

chasing is hard work and takes years of practice to get it right. It is a skill in its own right.

I stopped letting my customers try to save money.

as for a table of sizes. Ask your electrician. He is the one who is specifying sizes and the design. No one else can do this for you other than the designer who is going to sign the work off.

Thanks Pete. This is a listed building so I am literally not allowed to chase. I am allowed to use capping or conduit though so these will be secured to the brickwork and plastered over. The joys of having to please the conservation officer

 

[Deleted account]

Thanks Pete. This is a listed building so I am literally not allowed to chase. I am allowed to use capping or conduit though so these will be secured to the brickwork and plastered over. The joys of having to please the conservation officer

That makes this soooooo much more easier. Are you using plastic capping or metal.

personnally I hate plastic, but thats your sparkies shout.

plastic oval I do like, but again speak to your sparky. He has probably got loads of different size oval conduit On his van at all times. Its not expensive. or at least it didn’t used to be.
As a sparky I would use what I had in stock and buy extra, more than I needed and any that was not used I would use on other jobs.

Is this job materials and labour, or just labour.

if it’s materials and labour get your sparky to purchase conduit. If he buys too much he can keep the excess.

 

[tvrulesme]

Is this job materials and labour, or just labour.

Just labour on this one but you're absolutely right that I should ask the sparky. My preference would be steel capping though I thought the oval conduit would probably give better protection against the lime plaster.

 

[Deleted account]

Has the sparky given you any specification or a list of materials or is he letting you chose what to use.

 

[tvrulesme]

Has the sparky given you any specification or a list of materials or is he letting you chose what to use.

I haven't got that far yet. I was looking at what was possible so I go informed when I look for a spark to use

 

[Deleted account]

I haven't got that far yet. I was looking at what was possible so I go informed when I look for a spark to use

Sorry I thought you had already instructed a sparkie.

wait til you have a sparkie lined up then start making these decisions. It will be easier that way.

 

[telectrix]

oval conduit we use to call egatube as that was the most popular. 25mm is just right for 2 x 2.5mm T/E. for larger cables go 38mm for the 4.0mm x 2. try the 38mm on the 6mm before going bigger. that aside, i find it easier to fit the tube and the cable drops at the same time, feeding the cable into the tube before the tube is fixed to the wall.

 

[tvrulesme]

oval conduit we use to call egatube as that was the most popular. 25mm is just right for 2 x 2.5mm T/E. for larger cables go 38mm for the 4.0mm x 2. try the 38mm on the 6mm before going bigger. that aside, i find it easier to fit the tube and the cable drops at the same time, feeding the cable into the tube before the tube is fixed to the wall.

Thanks so much. And I assume a bucket full of lube....

 

[brianmoooore]

It depends to a large degree on the makes of both the cable and the conduit.
I have fed thousands of 2 x 2.5mm T&E drops down 20mm oval conduit drops, without resorting to any lubricant, but only ever with selected makes of cable and conduit. Prysman and M/Tuflex in recent years.
Telectrix is correct about fitting the cable drops into the tube as you install, and then fixing the tube in place.

 

[Petej999]

I haven't got that far yet. I was looking at what was possible so I go informed when I look for a spark to use

It will be difficult to fit oval conduit prior to any wiring, a bad descision to do this most oval tub installs require the tube to be fitted during the first fix stage, NOT as an aid memoir for the electrician, a bad decision in my book

 

[telectrix]

a tip for fitting oval tube is what I used to do. for 25mm tube, cut your chase 25mm wide but put 2 or 3 kinks of about 3mm in the chase. then the tube can be tapped in without the expense and drilling time of using clips, if the plaster is in decent condition.

 

[HappyHippyDad]

I realise the OP isn't chasing, so apologies for not sticking to the thread. I chase using the triple blade on the metabo wall chaser, it takes out the perfect size chase for 25mm oval conduit. Similar to what Tel said above, the conduit squashes into the chase pretty snuggly so it stays in place and is easy to get a few concrete screws (wall dogs) in to keep it firmly in.

 

[tvrulesme]

I realise the OP isn't chasing, so apologies for not sticking to the thread. I chase using the triple blade on the metabo wall chaser, it takes out the perfect size chase for 25mm oval conduit. Similar to what Tel said above, the conduit squashes into the chase pretty snuggly so it stays in place and is easy to get a few concrete screws (wall dogs) in to keep it firmly in.

Nice tip. Honestly I don't think anyone has stuck to the thread

Original question was if there is a simple table available to show what size cable(s) will fit into oval conduit of various sizes?

Guessing by all the tangents the answer is no.

 

[SJD]

Just wondering if there is a simple table available to show what size cable(s) will fit into oval conduit?
Specifically 2 x 6mm2 T+E cables (induction hob and oven) and 2 x 4mm2 T+E (socket radial)

Oval conduit comes in 13,16,20,25,32 and 38mm sizes. Which of those sizes will fit the 2 x cables for 6mm and 4mm respectively?

I'm not aware of a simple table.

Mostly I'd use 16, 20 and 25mm oval conduit (actually they are the only sizes I keep).
What you can push down a length depends (a) on how long a length, and (b) how straight the cable it.

Cable drawn nicely of the reel will push down conduit a lot easier than kinked and straightened out cable (it never properly straightens). This can make a huge difference.

For 6mm2 T&E, I'd likely use separate 20mm oval conduits, one for each of the two cables, but I'd guess you'd need 32mm oval conduit it you really wanted to put both in one length.

For 4mm2 T&E, you can fit two cables in a 25mm oval conduit, or a single cable in 16mm oval conduit.

Is the oven big & industrial, just wondering why you need 6mm2 cable, most domestic ovens would be wired in 2.5mm2 or 4mm2.

If you are buying conduit yourself, avoid some of the cheap and nastly types (e.g. Screwfix), which are not very robust and easily crack. They are cheap for a reason. I find TLC seem to do a reasonable type.

 

[tvrulesme]

I'm not aware of a simple table.

Mostly I'd use 16, 20 and 25mm oval conduit (actually they are the only sizes I keep).
What you can push down a length depends (a) on how long a length, and (b) how straight the cable it.

Cable drawn nicely of the reel will push down conduit a lot easier than kinked and straightened out cable (it never properly straightens). This can make a huge difference.

For 6mm2 T&E, I'd likely use separate 20mm oval conduits, one for each of the two cables, but I'd guess you'd need 32mm oval conduit it you really wanted to put both in one length.

For 4mm2 T&E, you can fit two cables in a 25mm oval conduit, or a single cable in 16mm oval conduit.

Is the oven big & industrial, just wondering why you need 6mm2 cable, most domestic ovens would be wired in 2.5mm2 or 4mm2.

If you are buying conduit yourself, avoid some of the cheap and nastly types (e.g. Screwfix), which are not very robust and easily crack. They are cheap for a reason. I find TLC seem to do a reasonable type.

Perfect, thank you so much. Exactly what I was looking for. Yes I use TLC for everything. There's one just down the road

Oven wise I will leave the cabling up to the Spark, just interested in the possible at the moment. I'd rather pay extra and oversize with 6mm even if the oven could comfortably be in 4mm. I have tonnes of spares in the consumer unit so it's really just a few pounds more for 4/5m of cable between 4mm and 6mm

 

[HappyHippyDad]

I'm not aware of a simple table.

Mostly I'd use 16, 20 and 25mm oval conduit (actually they are the only sizes I keep).
What you can push down a length depends (a) on how long a length, and (b) how straight the cable it.

Cable drawn nicely of the reel will push down conduit a lot easier than kinked and straightened out cable (it never properly straightens). This can make a huge difference.

For 6mm2 T&E, I'd likely use separate 20mm oval conduits, one for each of the two cables, but I'd guess you'd need 32mm oval conduit it you really wanted to put both in one length.

For 4mm2 T&E, you can fit two cables in a 25mm oval conduit, or a single cable in 16mm oval conduit.

Is the oven big & industrial, just wondering why you need 6mm2 cable, most domestic ovens would be wired in 2.5mm2 or 4mm2.

If you are buying conduit yourself, avoid some of the cheap and nastly types (e.g. Screwfix), which are not very robust and easily crack. They are cheap for a reason. I find TLC seem to do a reasonable type.

Well done for answering the question

 

[telectrix]

myearlierpostgave a size for 2 x 2.5mm; 2 x 6.0mm. always better a bit too big than too small.. at least, that's what'er indoors says.and she knows nowt about electrics except that if i fit it, her appliances work.