To put you in the picture and more info as possible, I have a 4mm SWA cable from the property CU to the summerhouse CU with 2 double socket on a ring mains + lights.The question is, I have a pergola behind the summerhouse which is all under cover with polycarbonate roofing sheets (no cable will be exposed to rain), I want to split the ring mains from the summerhouse to extend the ring with a JB in the roof area which is easily accessible and put in 2 more waterproof socket in the pergola area on the inside upright support (6"x3" timber) approx 500mm from ground level, can I carry on using t&e 2.5mm cable clip to the wood frame or put it in trunking or swa cable,flexible conduit etc, bearing in mind it's all undercover as the three sides are fenced off and only 1 side is open from entrance & no rain can get in.
Extending ring mains from summerhouse to pergola area.
- Thread starter masona
- Start date
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B
Big_Spark
Masona, firstly I hope that all the existing is protected at either end by RCD's, secondly, although people do, T&E is not designed for external use, being under a cover may keep the rain off, but it is still exposed to the elements, so should not really be used..in trunking or clipped direct.
You could use SWA, and realistically should, however should you choose that you do not want to use SWA there are a couple of alternatives.
First you could use FP200, this is cold weather rated.
Secondly, you could use Arctic Blue, in 2.5mm2. This is rated down to..I believe -25C, so will be more than capable of handling the exposure..the blue colour of the outer sheath may be an issue, but it is paintable..not solvent based paints though.
Those two may be a little on the expensive side for such a job though.
One way to make your life easier would be to buy SWA as a Four (4) core cable or Six (6) core cable. This would allow you to use only one single run out and incorporate both parts of the ring in one cable.
If the run is short, and you use the CORRECT glands (CW NOT BW), you can use the SWA as the CPC, hence 4 core, however if the cost is not significantly higher you could use 6 core to ensure two CPC's to make a conventional ring..one intersting point here, if you use SWA, you only need 1.5mm cores not 2.5mm cores. This is because SWA has a higher load rating than T&E.
You could use SWA, and realistically should, however should you choose that you do not want to use SWA there are a couple of alternatives.
First you could use FP200, this is cold weather rated.
Secondly, you could use Arctic Blue, in 2.5mm2. This is rated down to..I believe -25C, so will be more than capable of handling the exposure..the blue colour of the outer sheath may be an issue, but it is paintable..not solvent based paints though.
Those two may be a little on the expensive side for such a job though.
One way to make your life easier would be to buy SWA as a Four (4) core cable or Six (6) core cable. This would allow you to use only one single run out and incorporate both parts of the ring in one cable.
If the run is short, and you use the CORRECT glands (CW NOT BW), you can use the SWA as the CPC, hence 4 core, however if the cost is not significantly higher you could use 6 core to ensure two CPC's to make a conventional ring..one intersting point here, if you use SWA, you only need 1.5mm cores not 2.5mm cores. This is because SWA has a higher load rating than T&E.
Yes, they're both protected at both ends.FWL_Engineer said:
Thanks for that, nice to have a choice though !
ps: one last thing, would it be a good idea to put in a earth rod in, to the summerhouse CU as it would be the quickest route instead of earthing out back to the property CU ? or am'I going over the top ?
Thanks in advance.
B
Big_Spark
You need to be careful when putting Earth rods in.
Firstly they need to be put in and tested by someone with experience of this, it is not as simple as hammering a length of copper stack into the ground, wiring up and forgetting about it.
Secondly, they should always be installed in enclosures to ensure the connection does not corrode, I have found coating the connection with Graphite greece and covering with a plastic bag helps to preserve the connection from the elements..obviously after it has been tested.
Thirdly, you need to be careful about introducing parallel Earth paths, doing this could seriously effect how the protective devices operate and potentially could result in a dangerous situation.
Firstly they need to be put in and tested by someone with experience of this, it is not as simple as hammering a length of copper stack into the ground, wiring up and forgetting about it.
Secondly, they should always be installed in enclosures to ensure the connection does not corrode, I have found coating the connection with Graphite greece and covering with a plastic bag helps to preserve the connection from the elements..obviously after it has been tested.
Thirdly, you need to be careful about introducing parallel Earth paths, doing this could seriously effect how the protective devices operate and potentially could result in a dangerous situation.
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I understand how ring mains work, but how do you use a single run 4 core SWA cable to incorporate both parts of the ring in one cable to socket to socket using waterproof socket type ? Do you cut all four cable or only two at the socket ?FWL_Engineer said:
B
breezer
you have to cut the cable to fit the gland, so at each socket you have 8 wires.(red, yellow,(live) black & blue(neutral))
Join 4 back together (colour to colour, say yellow & blue)
that leaves 4
2 in 2 out (2 red 2 black) these get connected to socket as per "normal"
at last socket connect red to yellow
black to blue
connect as normal to socket.
obviously you should tape the yellow with red and the blue with black
this means you still have a ring, but idealy if you use 6 core you could do similar with earth wire
Join 4 back together (colour to colour, say yellow & blue)
that leaves 4
2 in 2 out (2 red 2 black) these get connected to socket as per "normal"
at last socket connect red to yellow
black to blue
connect as normal to socket.
obviously you should tape the yellow with red and the blue with black
this means you still have a ring, but idealy if you use 6 core you could do similar with earth wire
B
breezer
crimps, but decent ones and a good ratchet crimper
One more question,
What is the correct way of joining the 2.5mm2 t&e cable to 2.5mm2 SWA cable to extend the ring mains bearing in mind this will be inside the summerhouse roof section.A picture would be great, thanks in advance.
What is the correct way of joining the 2.5mm2 t&e cable to 2.5mm2 SWA cable to extend the ring mains bearing in mind this will be inside the summerhouse roof section.A picture would be great, thanks in advance.
B
breezer
masona said:
I have just re read your post, i did wonder why you wanted a picture of a summer house.
To connect the swa cable to a T & E you should "make off" the swa gland into a small adapatble box you should get an "Earth tag" with the swa cable, you can use this (it fits on gland before nut) to connect your earth wire to. (via crimp and small nut and bolt)
sorry i have no pictures of glands being made off, but tlc will have glands
B
breezer
but does the remiander answer your q?
B
Big_Spark
Masona, the PVC box is the better option as it will not corrode, however I would not buy the one in your picture, I would get one which you have to drill holes in, that way you have no rubber grommets that could pop out if the box were distrubed in someway..but that's just me 
You can get 5 core SWA, all the cores will likely be white and numbered one to five.
You can get 5 core SWA, all the cores will likely be white and numbered one to five.
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