Use of THW outside

[MJCM]

I am going to use THW 16mm² in HDPE conduit outside, but for the last 1-2 meters it will be outside of the HDPE.

 

(In those 1-2 last meters) It will be little exposed to the elements (no Rain but some sunshine could hit it), so my question is, can I use THW in this situation or do I need to switch over to NYY?

 

Thx

[MJCM]

Reading the PDF about THW I think I need to go with NYY because of this warning

 

Quote

 Do not install in duct in ground or direct burial in ground

210531_450!750V 70C 60227 IEC 01 (THW)-REV 04.pdf

[sometimewoodworker]

1 hour ago, MJCM said:

Reading the PDF about THW I think I need to go with NYY because of this warning

 

210531_450!750V 70C 60227 IEC 01 (THW)-REV 04.pdf 284.46 kB · 2 downloads

That depends of @MJCM is going to bury the HDPE or not. If not in ground the THW is ok

[MJCM]

19 minutes ago, sometimewoodworker said:

That depends of @MJCM is going to bury the HDPE or not. If not in ground the THW is ok

Yes that was our intention to bury the HDPE the first 10-15 meters and then it will come up and then to it's intended location above ground.

 

So THW won't be any good for this. Too bad!

[MJCM]

Now also the hunt is on for NYY 2x1,5mm² for the CT cable ???? was also thinking of using THW for that

 

Edit: Question please is there any other cable that is suitable for burying in HDPE that is NOT NYY?

 

[Crossy]

4 minutes ago, MJCM said:

Now also the hunt is on for NYY 2x1,5mm² for the CT cable ???? was also thinking of using THW for that

 

For your CT (low voltage, low current) regular insulated and sheathed (flex) would be fine.

 

The issue with THW is that it's only single-insulated and PVC isn't totally waterproof. Underground conduit WILL fill with water whatever you do. After an indeterminate period your THW would go leaky and at mains voltages fizzing may occur.

[MJCM]

thx @Crossy

 

May I ask what do you mean by this?

 

13 minutes ago, Crossy said:

regular insulated and sheathed (flex) would be fine.

We just asked our suppliers and NYY 2x1,5mm² is NOT available the only one available is 2x2.5mm²

 

And what about VCT? (Even worse then THW??)

 

The HDPE we are going to use is originally for water (blue stripe) as we have ... loads of it left and we were told that the Blue Stripe is stronger then the one for Electric (red stripe) but I guess YMMV.

[Crossy]

2 minutes ago, MJCM said:

May I ask what do you mean by this?

 

VCT, but NOT for mains voltage!!!

 

[MJCM]

13 minutes ago, Crossy said:

 

VCT, but NOT for mains voltage!!!

 

Only used for the CT from the inverter to the house

 

Main cables will be NYY!

[bluejets]

In all my years as a lecky, I have never used building cable (single insulated) underground.

Reason being, I have seen too many blow up as the insulation deteriorates (especially the red insulated) and as water creep in.

Insulation goes like that of a dry clay creek bed.

Most that do use it are simply trying to save some bucks without considering the long term effect.

 

Double insulated (TPS) best approach if you want it to last.

If any low voltage cabling is run in the same conduit, it to should be mains rated insulated and sheathed cable.

Any comms should be a separate conduit entirely and spaced some 300mm horizontally away from mains conduits.

[MJCM]

42 minutes ago, bluejets said:

Any comms should be a separate conduit entirely and spaced some 300mm horizontally away from mains conduits.

Thx, So you are saying that I need to pull another HDPE Conduit just for the CT cable (which is going to be VCT 2x1.5mm²)??

[sometimewoodworker]

2 hours ago, MJCM said:

Thx, So you are saying that I need to pull another HDPE Conduit just for the CT cable (which is going to be VCT 2x1.5mm²)??

@MJCM bluejets is giving you a summary of the way that will virtually guarantee no interference and is in all the guides to cabling.

He is missing the point that very many people ignore the guides have both data and mains cables running side by side and see no significant, or any, signal degradation. Now if you are not using twisted pair (you aren’t) this makes interference much more likely though still not certain.

 

My inclination would be to run the cables together (assuming the HDPE is above ground) and see if there is a problem. You can always run another length of HDPE and VCT 2x1.5mm² (neither of these are very expensive ) to cure the problem.

[MJCM]

Thx @sometimewoodworker

 

1 hour ago, sometimewoodworker said:

My inclination would be to run the cables together (assuming the HDPE is above ground) and see if there is a problem.

The problem is that it has to be underground!

 

I will be running 2x HDPE (all preparations like holes drilled etc etc have already been done)

 

1st HDPE - Will have 1x10 mm² NYY plus the VCT 2 x 1,5mm²

2nd HDPE - Will have only 1x10mm² NYY

 

Why not both NYY in 1 HDPE you may ask? This in case I want to upgrade and use 16mm² NYY and 2 of those will NOT fit into 1 HDPE.

 

1 hour ago, sometimewoodworker said:

You can always run another length of HDPE and VCT 2x1.5mm² (neither of these are very expensive ) to cure the problem.

HDPE we have ....loads but the preparations to have the HDPE (both)  exit and enter have already been done thus a lot more work for 1 extra HDPE just for that VCT 2x1.5mm². And again it must be underground.

 

If I could find 2x1.5mm² or even 2x2,5mm² NYY (not a Whole roll (need approx 30(ish)M only)

 

Maybe have found a lead to NYY 2x1.5mm²

[sometimewoodworker]

1 hour ago, MJCM said:

If I could find 2x1.5mm² or even 2x2,5mm² NYY (not a Whole roll (need approx 30(ish)M only)

 

@MJCM I am virtually certain that a really good electrical supply shop will be able to supply one if not both.
 

A competent quality supply shop will be holding stocks of the more common cables,  NYY is one of those, and they will cut to length. 
 

You have chosen to limit the information in your profile so I don’t know if I can give relevant information, AFIR you may have given it in one of your posts.

 

Note I am talking about a specialist electrical supply shop not one of the big chain stores.

[MJCM]

Thx @sometimewoodworker

 

I am in Buriram and I have called all the shops around (and in Surin) even talked to the sales at DoHome and our builders merchant and they only sell per 100m roll or don’t have it (for example dohome and builders merchant). 10mm and bigger no issue but smaller not, the sales advised me to use VCT ????

 

also contacted many sellers on Lazada and I may have one option, but they haven’t responded to our message yet. 

 

will go tmrw anyway to do some extra shopping (need some more HDPE connectors amongst other things) and I will visit Global and TW  and HP.

 

if that all fails I am going for VCT together with the 1x NYY in HDPE together and will seal the ends of the HDPE with a bit of PU foam to prevent any ingress. 

 

[sometimewoodworker]

27 minutes ago, MJCM said:

Thx @sometimewoodworker

 

I am in Buriram and I have called all the shops around (and in Surin) even talked to the sales at DoHome and our builders merchant and they only sell per 100m roll or don’t have it (for example dohome and builders merchant). 10mm and bigger no issue but smaller not, the sales advised me to use VCT ????

 

also contacted many sellers on Lazada and I may have one option, but they haven’t responded to our message yet. 

 

will go tmrw anyway to do some extra shopping (need some more HDPE connectors amongst other things) and I will visit Global and TW  and HP.

 

if that all fails I am going for VCT together with the 1x NYY in HDPE together and will seal the ends of the HDPE with a bit of PU foam to prevent any ingress. 

 

@MJCM That helps for this post, but filling in your profile will help for all of them.

 

I did specifically exclude the chain shops these include  dohome, global house, HomePro, Thai Watsadu, equally of no use are any shop that is NOT a specialist electrical supply shop and a reasonably sized one at that, naturally this includes builders merchants.

 

I do know of one, but that is hardly helpful as they are in Udon Thani. Personally I doubt that the kind of shop you need will have a significant online presence and they are unlikely to sell indirectly. It is also unlikely that the suppliers on the various online platforms will cut to length in my experience.

[bluejets]

4 hours ago, sometimewoodworker said:

bluejets is giving you a summary of the way that will virtually guarantee no interference and is in all the guides to cabling.

He is missing the point that very many people ignore the guides have both data and mains cables running side by side and see no significant, or any, signal degradation.

It has that property but the separation also covers against underground blow ups.

The last thing one wants is mains supply down a comms cable and worse yet, injected into comms company gear as they WILL track you and hold you responsible for any damage to their gear.

[MJCM]

59 minutes ago, sometimewoodworker said:

I did specifically exclude the chain shops these include  dohome, global house, HomePro, Thai Watsadu, equally of no use are any shop that is NOT a specialist electrical supply shop and a reasonably sized one at that, naturally this includes builders merchants.

I know you did, but I want no stone left unturned if you know what I mean.

 

I found a store in Buriram that MAY have it, will go and visit them tmrw.

(Found them by calling all electric shops (that Google brought up) in Buriram

 

39 THB per Meter. NYY 2x1.5mm²

 

Will report back!

 

 

[MJCM]

46 minutes ago, bluejets said:

It has that property but the separation also covers against underground blow ups.

The last thing one wants is mains supply down a comms cable and worse yet, injected into comms company gear as they WILL track you and hold you responsible for any damage to their gear.

Thx for the warning.

 

But may I ask if a mains cable blows (the 10mm²) won't it also damage the separate HDPE with the 2x1.5mm² as well as it's laying almost next to it or are you saying we have to separate that 3rd HDPE to a location somewhere else.

 

And could cause a CT cable that much damage to their gear??

 

And what about the protection at the Inverter (CU Box) etc etc won't that prevent it?

[sometimewoodworker]

19 minutes ago, MJCM said:

Thx for the warning.

 

But may I ask if a mains cable blows (the 10mm²) won't it also damage the separate HDPE with the 2x1.5mm² as well as it's laying almost next to it or are you saying we have to separate that 3rd HDPE to a location somewhere else.

 

And could cause a CT cable that much damage to their gear??

 

And what about the protection at the Inverter (CU Box) etc etc won't that prevent it?

The ideal is a 300 mm separation as BJ said above so if you are going to the trouble of separating then that’s what you need.

 

A cable fault is highly unlikely to actually “blow” though it could. It’s much more likely for the insulation to deteriorate with potentially arcing between conductors. 
 

For your CT (I’m not really clear on the use of that) certainly if it’s designed for 12V and you stick 220v down it there is a good chance of damage even more so if you shove some significant amount of amps via a fault.

 

It is certainly possible to design for the 12V equipment to be tolerant of high voltage and current, the problem is that nobody does that as it costs money. Though is quite possible that military equipment might be designed for that at a unit cost of 100 times the civilian stuff.

[MJCM]

Thx @sometimewoodworker

 

You are very helpful.

 

We could bury the HDPE 300mm apart but at the starting point they will be close together. Look at this picture on the left you will see 2 HDPE sticking out of the wall (which is the starting point for the Cable to go to the House)

 

 

The whole exercise is about to connect a Solar Inverter to the House (via the 10mm² NYY) and In this instance the CT clamps on the incoming grid connection (near the CU in the House) and monitors the grid energy flow and is connected to the Inverter

[sometimewoodworker]

5 hours ago, MJCM said:

We could bury the HDPE 300mm apart but at the starting point they will be close together. Look at this picture on the left you will see 2 HDPE sticking out of the wall (which is the starting point for the Cable to go to the House)

You do the best you can with what you have. If it later turns out there is a problem then you can deal with it then. 
 

Bury 300mm apart as much as possible, ignore the end points closeness. Have a beer.

[MJCM]

8 hours ago, sometimewoodworker said:

Bury 300mm apart as much as possible, ignore the end points closeness.

Shall discuss it with our builder when he comes.

 

Will report back on the NYY.

 

 

[bluejets]

14 hours ago, MJCM said:

Look at this picture on the left you will see 2 HDPE sticking out of the wall (which is the starting point for the Cable to go to the House)

There is a minimum separation of 100mm there as well if you want to follow recommendations.

Hope is that you don't intend to include them both in the one mounting block or fitting.

 

 

[MJCM]

23 minutes ago, bluejets said:

There is a minimum separation of 100mm there as well if you want to follow recommendations.

Hope is that you don't intend to include them both in the one mounting block or fitting.

 

 

 

Outside (and underground) 300mm oke, but those fittings stay (not going to ..... the finished wall up)

 

Probably next you are going to say that I can't use HDPE BLUE stripe for Electric Cable

[sometimewoodworker]

1 hour ago, MJCM said:

Probably next you are going to say that I can't use HDPE BLUE stripe for Electric Cable

No. Why? It’s just black and blue not black and red. ????

 

[MJCM]

17 minutes ago, sometimewoodworker said:

No. Why? It’s just black and blue not black and red. ????

 

Question, do you know why HDPE Blue stripe is a lot more expensive then the HDPE Red Stripe? (same diameter)

 

The only answer I have gotten was that the Blue Stripe is much thicker to handle higher pressure from Water. Does that make any sense?

[longball53098]

I do not see any mention of his supply store. I member that I have not seen for a long time swore high and low this place could supply all a persons needs.

 

https://www.facebook.com/BuriramRuangsangthai/

 

They should have all the cables needed and the HPE too

[sometimewoodworker]

3 hours ago, MJCM said:

Question, do you know why HDPE Blue stripe is a lot more expensive then the HDPE Red Stripe? (same diameter)

 

The only answer I have gotten was that the Blue Stripe is much thicker to handle higher pressure from Water. Does that make any sense?

It certainly would make sense, I don’t have the 2 types so can’t comment, however as you are burying it you probably want the thicker one.

[MJCM]

4 hours ago, longball53098 said:

I do not see any mention of his supply store. I member that I have not seen for a long time swore high and low this place could supply all a persons needs.

 

https://www.facebook.com/BuriramRuangsangthai/

 

They should have all the cables needed and the HPE too

That was 1 of the first shops I called .No Have. I have been a Loyal customer of them and when Bob was still there we visited often. We now only call them and have them deliver stuff (as they don't charge for deliveries unlike the other ones)

 

  

4 hours ago, longball53098 said:

 

They should have all the cables needed and the HPE too

The HDPE I still have a couple rolls both Water and Electric Graded, so that is not an issue and never was