Joining electrical conduit

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gzt

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#311959 1-Mar-2024 11:19

I'm running conduit outside for network cable. How is conduit usually joined?

I'm likely to use 4 meter length Deta conduit from Bunnings.

Two pieces fit together no need for a joiner. Do I need to seal with silicon or something like that?

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#3201953 1-Mar-2024 11:32

It's been a while since I've done this, but a 'solvent cement' was used to basically melt the fitted parts together and keep out the elements.

https://www.bunnings.co.nz/products/bathroom-plumbing/plumbing/plumbing-parts-tools/pvc-solvent-cement

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neb

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#3201970 1-Mar-2024 12:31

If you're getting it from Bunnings look for the generic tubes of solvent cement which from memory are under $10, not the obscenely overpriced Marley ones. Also if you've only got one or two to join you can try model glue, which is also a solvent-based cement.

Edited to add: And if you're using long straight runs you need to drop in an expansion joint every 6m, they're rubbery concertina-style connectors that deal with the conduit getting longer/shorter with temperature variations.

Edited a second time: It looks like poly cement, used for plastic models, isn't the same as PVC cement, reports on model-making sites are that it'll hold together fine when used but proper PVC cement is recommended.

richms

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#3202093 1-Mar-2024 15:05

Its not the white stuff that guttering uses either, that is different and seems to not stick conduit uPVC at all.

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gzt

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#3202141 1-Mar-2024 16:56

I didn't see anything specific in the Deta area. Nothing found on Bunnings web yet.

richms

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#3202145 1-Mar-2024 17:01

You can get ados at mitre10 too.

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neb

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#3202147 1-Mar-2024 17:08

richms:
Its not the white stuff that guttering uses either, that is different and seems to not stick conduit uPVC at all.

Hmm, the Bunnings folks, and in this case an older tradie-type not one of the younger staff, said to use that.

For the OP, it's not near the conduit, you need to go to the plumbing section. At least at the local Bunnings it was in three different locations, overpriced Marley pots of it near the drainage stuff, overpriced Marley tubes by the downpipe stuff, and then a sole box of the cheaper one off to one side somewhere.

Edited to add: Just did a quick Google and sites like The Spruce tell you to use PVC cement. Could it be that you hit a bad/old batch?

neb

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#3202154 1-Mar-2024 17:16

gzt: I didn't see anything specific in the Deta area. Nothing found on Bunnings web yet.

The web site only shows the generic stuff carried by all stores and may not even show that, e.g. the cable clips that mdf suggested in another thread aren't shown on their site. It's possible that the cheaper tube I got may have been a local-store-only special, it was a while back that I got it.

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richms

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#3202159 1-Mar-2024 17:26

neb:
richms:

Its not the white stuff that guttering uses either, that is different and seems to not stick conduit uPVC at all.

Hmm, the Bunnings folks, and in this case an older tradie-type not one of the younger staff, said to use that. For the OP, it's not near the conduit, you need to go to the plumbing section. At least at the local Bunnings it was in three different locations, overpriced Marley pots of it near the drainage stuff, overpriced Marley tubes by the downpipe stuff, and then a sole box of the cheaper one off to one side somewhere. Edited to add: Just did a quick Google and sites like The Spruce tell you to use PVC cement. Could it be that you hit a bad/old batch?

The white stuff seems to be made to fill the gaps between spouting and the joiners etc and act as a sealant as well as a glue, when I used it on normal grey conduit it pulled apart where I had the sweep elbow on it when I was yanking on the draw wire. I scraped it all off and used the yellowy transparent stuff with the brush in the lid and that stuck really well.

Richard rich.ms

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#3202179 1-Mar-2024 17:58

I used the generic uPVC white cement from Bunnings on my Deta Conduit run, and my sparky uses the same. After joining it, I wasn't getting it apart again!

tweake

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#3202241 1-Mar-2024 21:04

if you using the plumbing pvc cement your meant to use the primer first (which is acetone). however many sparkies just use silicone. i would recommend a polymer sealant like sellys all clear. that will glue it pretty well.

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#3202243 1-Mar-2024 21:19

tweake:
if you using the plumbing pvc cement your meant to use the primer first (which is acetone).

I asked a plumber friend a while back and he said it's required for pipes carrying liquid but (and I hope I'm not misquoting him here) not others. So for conduit it could just be an unnecessary expense. Worst-case you're paying $30 for Marley primer and another $30 for PVC cement to join a few lengths of $7 Deta conduit.

While I was looking for primer prices I noticed that M10 has Ados PVC cement for $14, that's probably the cheapest you're likely to find, and only costs as much as two 4-metre lengths of conduit.

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#3202259 2-Mar-2024 00:48

tweake:

if you using the plumbing pvc cement your meant to use the primer first (which is acetone). however many sparkies just use silicone. i would recommend a polymer sealant like sellys all clear. that will glue it pretty well.

Silicon often doesn't last that long before it fails, and sometimes doesn't stick well to plastics from my own experiences. Don't plumbers use PVC cement when joining PVC waste pipes, as is essentially welds the PVC surfaces toegther. So would have thought conduit would be the same. https://pvcfittingstore.com/pages/two-ways-to-connect-pvc-pipe-and-fittings

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#3202283 2-Mar-2024 10:17

You don't need primer. The Ados PVC pipe cement will be fine.

tweake

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#3202345 2-Mar-2024 11:32

neb:
tweake:

if you using the plumbing pvc cement your meant to use the primer first (which is acetone).

I asked a plumber friend a while back and he said it's required for pipes carrying liquid but (and I hope I'm not misquoting him here) not others. So for conduit it could just be an unnecessary expense. Worst-case you're paying $30 for Marley primer and another $30 for PVC cement to join a few lengths of $7 Deta conduit. While I was looking for primer prices I noticed that M10 has Ados PVC cement for $14, that's probably the cheapest you're likely to find, and only costs as much as two 4-metre lengths of conduit.

its required for certed applications. eg fire alarm guys use it for conduit. in fact they replace the bottle each day, so we got a few half empty bottles given to us. its just acetone which you probably have at home already. it helps clean the plastic as well so you don't get failed joins. edit: it wouldn't hurt to clean it with acetone regardless of what you glue it with. just to make sure its clean.

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#3202346 2-Mar-2024 11:35

mattwnz:

tweake:

if you using the plumbing pvc cement your meant to use the primer first (which is acetone). however many sparkies just use silicone. i would recommend a polymer sealant like sellys all clear. that will glue it pretty well.

Silicon often doesn't last that long before it fails, and sometimes doesn't stick well to plastics from my own experiences. Don't plumbers use PVC cement when joining PVC waste pipes, as is essentially welds the PVC surfaces toegther. So would have thought conduit would be the same. https://pvcfittingstore.com/pages/two-ways-to-connect-pvc-pipe-and-fittings

correct.

thats why polymer sealant is better because it tends to glue well and it doesn't crack. plus you may already have it at home.

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