70mm SWA

[zeroberto]

Just connected a 70mm 3 core SWA sub main. I'm in the sticks, no Industrial work here at all so out of the ordinary for us (few farm buildings etc) & our usual swa size is 16 or 25mm. Sheltered life I know!

Anyway just want to tip my hat to you guys who work with this size of cable on a regular basis - what a beast to work with. Nice bit of job satisfaction when we finally got the glands on though.

Again, industrial guys I salute you!, hopefully never see this again for a few years.

cheers

 

[Engineer54]

If you use the heat shrink boots suggested by E54 with an external heat shrink sleeve it’s going to be as waterproof as you’ll ever get. The only weak point is where the gland meets the enclosure, if it’s misaligned you can distort the enclosure base plate. This is a point I would disagree with E54. a hefty cable glanded laid flat and then offered up will stress the cable and gland plate.

I first used HS boots on PILC cables as an apprentice, not adhesive lined, they used a hot melt tape. They were supplied with CMP lead lined glands. Brilliant things to work with, heat them up and the lining melted on to the lead sheath. I’d say probably better than a traditional plumbed termination.

RoB2 asked about them recently, no longer available!

Think your getting confused here, ''Boots'' cover and protect connections (normally MV/HV), ''Breakouts'' seal the ends/crotch of the cable after exposing the cores.

This very much depends on the location and how much room you have to work in. If your working out of a decent concrete cable trench under the switchboards, there shouldn't be any problem as far as not stressing the cable. More stress is put on the cable, when we've had to turn the cable for the cores to roughly line up with the terminations in the switch boards. It's also desirable to provide a cable support for heavy cables entering switchboards , panels and the like. Either way glanding off before or after the Top Hat gland has been fitted to the panel, it's a dam sight easier all round than glanding off with a typical SWA brass gland!!

Using glue lined crotch breakouts, with glue lined heat shrink tube, over the cable and gland (any gland type) will as Tony suggested make it about as waterproof as your ever going to get. We use this method all the time on all our external SWA cables...

 

[Engineer54]

I'm about do replace some glands on some cables that feed borehole pumps. The water company want the whole installation to be waterproofed. I don't know what glands they specified, but I don't think any gland will properly seal 100%, especially as in this instance, the cables don't enter the gland straight. They all pull to one side, and there's no way of securing them, as only the gland of the cable is above floor level, before the cable runs into the duct.
i suggested using glue lined heat shrink boots similar to those used on 11-33kv glands.
the water company use glue lined heat shrink for cable joints in submersible pumps, but I think our firm want something that they can say meets a BS for being waterproof. IP68 I reckon.

Well use whatever glands they specify and seal the lot (cable and gland) with glue lined heat shrink. Remember though, the thick walled glue lined heat shrink, will cool down to be as stiff and as hard as a solid plastic tube. They won't be at all flexible, i don't know if that will make a difference in your situation or not....

 

[johnboy6083]

The issue is that the JBs which connect the borehole pump flex to the SWA is in a flood plain. The water companies are spending lots of money protecting its water sources from floods. A contaminated aquifer costs a lot of money to put right.

the JBs are mounted about 100mm max from the floor level. The ducts run directly under the JB, the cable was glanded in an adjacent cable pit, and then pushed through the duct And into the JB. There's no slack to gain anywhere either.

I'm sure the glands they supply will be IP68, but only if the cable is supported, and enters the gland centrally and straight.
i think that of we use nylon or rubber sealing washers, along with glue lined shrouds, then we will eliminate one possible are of concern.
the next issue is the new JBs themselves, which I haven't seen yet.