Terminating Outside circuits with SWA

[Roger440]

I need to run 4 outside supplies.

 

As they will all be going underground at some point, they will all be in (various sizes) SWA.

 

Obviously they will run up the side of the house. At this point, assuming this is all legit, i would enter a junction box, where the SWA outer will be terminated and an earth cable then run to the consumer unit through the wall from the back of the junction box.

 

The rest of the conductors, my intention was to strip back enough of the outer sheathe after the earth termination to run the conductors all the way to the relevant breaker.

 

Reading on the interweb, it suggests that once i have stripped back the sheathing, from that point the cable is no longer "as manufactured" so technically not correct. If i dont do this, i would need to terminate in the junction box and join it to short bits of twin and earth. Which seems daft. And another joint for no good purpose.

 

Is the considered wisdom that im OK with running the SWA conductors all the way to the consumer unit? Correctly terminating the SWA outer at the junction box? 

[Nickfromwales]

51 minutes ago, Roger440 said:

Is the considered wisdom that im OK with running the SWA conductors all the way to the consumer unit? Correctly terminating the SWA outer at the junction box? 

Normally I terminate the SWA outside in a good quality JB and then run twin and earth into the dwelling through the outside wall. Terminate the equipment end with aIP switch / socket or IP isolator? What are the runs feeding? Any heavy loads? 

[Roger440]

Just now, Nickfromwales said:

Normally I terminate the SWA outside in a good quality JB and then run twin and earth into the dwelling through the outside wall. Terminate the equipment end with aIP switch / socket or IP isolator? What are the runs feeding? Any heavy loads? 

 

One will be the garage, so thats going to be 16mm. The others are, outdoor lights, sewage treatment plant, and electric gates.

[Nickfromwales]

Ok. Cant you just run the 16.0mm2 to the garage and then feed the other outside stuff from the second CU?

[Roger440]

2 minutes ago, Nickfromwales said:

Ok. Cant you just run the 16.0mm2 to the garage and then feed the other outside stuff from the second CU?

 

Ive got a second CU. It used to supply storage heaters, so got bags of capacity. Its still connected on the incoming side, but not on the outgiong.

 

Terminating all these supplies in a box just to swap to twin and earth is going to get awfully busy! 

 

 

[Nickfromwales]

If you can get them in without any major effort then fine, but I was referring to the second CU as DB2 in the garage, so you'd then only be penetrating the house once with the 16.

[Nickfromwales]

SWA's can then come off the garage CU then, metal clad, with ease.

[Roger440]

Think we are talking cross purposes? As there is no garage yet, im only installing the cable to it while i can. So ALL the supplies need to come from the house.

 

[Nickfromwales]

7 minutes ago, Roger440 said:

Think we are talking cross purposes? As there is no garage yet, im only installing the cable to it while i can. So ALL the supplies need to come from the house.

 

Well hurry up and build the garage then, simples !  

[Nickfromwales]

You could make the 16 off into a temporary outside unit in anticipation? 

[PeterW]

Just double check you really need 16 to the garage too as you may get away with 10 or even 6 depending on what is going in there. 

[Roger440]

7 minutes ago, Nickfromwales said:

You could make the 16 off into a temporary outside unit in anticipation? 

 

Im not worried about the load end. Just the house end.

[Nickfromwales]

1 minute ago, Roger440 said:

 

Im not worried about the load end. Just the house end.

My point. Are you better off / would it be easier to just get the one 16mm into the house and do everything else from the ( assume it will be ) DB3 ?

[Roger440]

4 minutes ago, PeterW said:

Just double check you really need 16 to the garage too as you may get away with 10 or even 6 depending on what is going in there. 

 

Well 10 "might" be OK. But given the equipment likely to be in it, and the possible distance (depending where it ends up, 16mm buys me a bit of margin. 10, not so much.

 

To put it in perspective:

3hp compressor

Possible boiler

Lighting (lots

2 x 3kw fans

3kw parts washer

Ramp

And if it goes at the other end of the garden, 200 ft away

[Roger440]

1 minute ago, Nickfromwales said:

My point. Are you better off / would it be easier to just get the one 16mm into the house and do everything else from the ( assume it will be ) DB3 ?

 

Possibly. but logistically it makes no sense. Plus the summer house and sewage supplies are already in. But need re-doing. Neither comply with much in the way of regs, and the sewage supply has only just been put in! So much for Part p registered electricians!

[PeterW]

16 it is then with that lot ..!! 

[Ed Davies]

3 hours ago, Roger440 said:

Reading on the interweb, it suggests that once i have stripped back the sheathing, from that point the cable is no longer "as manufactured" so technically not correct.

 

Ask the manufacturer if the individual cores are to an appropriate standard for use like that?

 

Would individual cores like this need to be in conduit through the wall and to the consumer unit as they're otherwise only single-insulated?

Edited December 9, 2018 by Ed Davies

[PeterW]

Other choice is to use three core and terminate the armouring in an adaptable box with something like a Piranha on the gland and then run the three core with its internal sheath through the wall. That would mean you have double protection on the cable a la T&E but have a separate earth running into the house for the armouring which only needs earthing at one end anyway if you use the 3rd core as the earth wire. This is what we did recently as had to run 16mm for a new feed and was quicker and cheaper than mucking about using the armouring tbh. 

[Jeremy Harris]

As long as you don't strip the individual wires from the second layer of encapsulating insulation it's OK to run that as if it were T&E.  It's still double insulated, and can be run from the SWA gland a short distance to another termination enclosure.  You just need to ensure that any cable (except a CPC) that can be touched without the use of tools to remove a cover is double insulated, be that by retaining the encapsulating insulation over any exposed length of cable, or running it in conduit.

[PeterW]

2 hours ago, Roger440 said:

3kw parts washer

 

Reminds me of a mate who like someone on this forum used to hoard and “repurpose” things and when the board went on their old dishwasher he took it into the workshop to turn into a parts washer - bear in mind this was a circa 1980’s dishwasher with an open element.......

 

According to the report, the door opened with such force that it bent the hinges and bowed the sides of the old dishwasher so it wouldn’t close again ... he’d used a mix of paraffin and “something else” to clean some old land rover bits, and put it on a 70c hot wash ... 

[Roger440]

1 hour ago, PeterW said:

Other choice is to use three core and terminate the armouring in an adaptable box with something like a Piranha on the gland and then run the three core with its internal sheath through the wall. That would mean you have double protection on the cable a la T&E but have a separate earth running into the house for the armouring which only needs earthing at one end anyway if you use the 3rd core as the earth wire. This is what we did recently as had to run 16mm for a new feed and was quicker and cheaper than mucking about using the armouring tbh. 

 

1 hour ago, JSHarris said:

As long as you don't strip the individual wires from the second layer of encapsulating insulation it's OK to run that as if it were T&E.  It's still double insulated, and can be run from the SWA gland a short distance to another termination enclosure.  You just need to ensure that any cable (except a CPC) that can be touched without the use of tools to remove a cover is double insulated, be that by retaining the encapsulating insulation over any exposed length of cable, or running it in conduit.

 

This is what i was trying to say.  So what you are suggesting you both believe to be acceptable?

 

If so, thats good

 

There is a school of thought on the electricians forum that it isn't. Using logic says its OK though.

 

[Roger440]

1 hour ago, PeterW said:

 

Reminds me of a mate who like someone on this forum used to hoard and “repurpose” things and when the board went on their old dishwasher he took it into the workshop to turn into a parts washer - bear in mind this was a circa 1980’s dishwasher with an open element.......

 

According to the report, the door opened with such force that it bent the hinges and bowed the sides of the old dishwasher so it wouldn’t close again ... he’d used a mix of paraffin and “something else” to clean some old land rover bits, and put it on a 70c hot wash ... 

Bet thestuff was clean though :):):)

 

The parts washer is actually purpose made with a waterbased cleaner. 

[Onoff]

Being pedantic but SWA in insulated and sheathed not double insulated. The insulation is only around the cores. There's then a sheath around those cores and the outer sheath over the armoured. Accepted that the sheaths have insulating properties.

[Roger440]

2 minutes ago, Onoff said:

Being pedantic but SWA in insulated and sheathed not double insulated. The insulation is only around the cores. There's then a sheath around those cores and the outer sheath over the armoured. Accepted that the sheaths have insulating properties.

 

Im guessing thats the basis for the argument?

[Jeremy Harris]

This photo of the 25mm² SWA core running up inside our meter cabinet shows what's OK.  We added a second layer of insulation (heat shrink sleeves) over the very short length of wire cores that were exposed where they went into the fused isolator to retain the double insulation that's mandatory:

 

 

6 minutes ago, Onoff said:

Being pedantic but SWA in insulated and sheathed not double insulated. The insulation is only around the cores. There's then a sheath around those cores and the outer sheath over the armoured. Accepted that the sheaths have insulating properties.

 

Accepted, but the intention behind the regulation is to ensure that there are two layers of insulation between the conductor and any area that could be accessed by a finger, without the use of tools.  As such, heat shrink over a single insulated conductor is acceptable, as is the internal encapsulating sheathing under the armour of SWA.  By the same token, the other end of that length of 25mm² SWA is terminated in an adaptable box with a gland, and the cores were fitted with grey heatshrink before being run to the consumer unit and to all intents and purposes are every bit as safe and robust as double insulated meter tails.