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-   -   BT Dropwire Terminal Boxes (https://www.vintage-radio.net/forum/showthread.php?t=162031)

pmmunro 8th Dec 2019 8:54 pm

BT Dropwire Terminal Boxes
 
I would like some guidance on telephone dropwire boxes please.

A few years ago, probably about 10, BT or possibly by that time Openreach, needed to change the dropwire from the local wood pole to our house. There was no problem with our service so something at the pole end must have needed attention.

The existing dropwire terminal box was a well sealed enclosure but it seems this had to be changed for the current standard issue item which was a cylindrical plastic shell closed by cable ties and made by Scotch. It looked much poorer quality than its predecessor and in fact failed by filling with water after about 2 to 3 years. This has now happened at least 3 times.

The Scotch junction box now seems to have been superseded by a Dex Green 2/4 https://www.bcedirect.co.uk/products...verhead-cables. I don't know if this is the Scotch item under a different name; can anyone say please?

If the Dex Green 2/4 is not just the Scotch terminal box under a different name is it reliable?

I would also be interested to know what the predecessors to these were and if they are still available.

PMM

Sean Williams 8th Dec 2019 10:35 pm

Re: BT Dropwire Terminal Boxes
 
I would have thought that the jelly locks inside the box would have kept any moisture out of the actual joint.

That being said, you cant beat a proper junction box with some nice 4BA screws, not too sure ADSL or VDSL will appreciate the significant capacitance the older boxes will create though.

Pellseinydd 8th Dec 2019 11:19 pm

Re: BT Dropwire Terminal Boxes
 
Quote:

Originally Posted by Sean Williams (Post 1197787)
I would have thought that the jelly locks inside the box would have kept any moisture out of the actual joint.

That being said, you cant beat a proper junction box with some nice 4BA screws, not too sure ADSL or VDSL will appreciate the significant capacitance the older boxes will create though.

One junction box was the 3pair/5pair BT Block Terminal 66B - usually came as an empty box to which a three pair terminal strip and 2 pair terminal strips could be added but often just used to protect two or three dropwires/internal wiring crimped with 'Connectors 8A' or 8B.

Then there was the later BT16A which was a small box to accommodate up to three crimped dropwires - came in various colours - white BT16A - or brown

Hope that is of some use?

Ian

G6Tanuki 9th Dec 2019 3:26 pm

Re: BT Dropwire Terminal Boxes
 
When I had a landline/ADSL-type broadband, originally there was a BT66B but there were interference issues (junction box was full of spiders....) and Openreach replaced it with a new wire from the pole and one of the black sausage-type junction boxes with the clip-on cover.

Jelly-crimps should be waterproof - I've seen plenty of instances where they have been underwater for weeks/months without problems.

Oldcodger 9th Dec 2019 10:14 pm

Re: BT Dropwire Terminal Boxes
 
Quote:

Originally Posted by Sean Williams (Post 1197787)
I would have thought that the jelly locks inside the box would have kept any moisture out of the actual joint.

That being said, you cant beat a proper junction box with some nice 4BA screws, not too sure ADSL or VDSL will appreciate the significant capacitance the older boxes will create though.

An old problem with the jelly crimps was that whilst the wires inside the crimp remained pure, corrosion crept inside the crimp and the copper /etc corroded away. It's a discussion I've had many a time with telecomms blokes from the time when jelly crimps were brought out.
However, I've got a joint to my rear security light that has not suffered over the last five years.
The monkeys doing the external cladding almost destroyed the original light and left me with a short end of the original cable, so I had to provide an external waterproof mains joint. I crimped the cables, then added tape to bulk out the cable to the shrunk heat shrink size, and heated a glue coated heat shrink to size. In older years, we would make off a joint and then add either an epoxy compound or simply add silicone to make the joint.

McMurdo 10th Dec 2019 11:44 pm

Re: BT Dropwire Terminal Boxes
 
I'm sure I saw a BT engineering memo which mentioned the phasing out of one brand of jelly crimp in favour of another due to 'ongoing corrosion problems'. I forget the brand going out and coming in but names mentioned were well known ones such as Tyco Telsplice or 3M Scotchlok or Kauden etc. Can't even remember where I saw it. (might've been Dexgreen)

Test Desk 11th Dec 2019 9:39 am

Re: BT Dropwire Terminal Boxes
 
I think current dropwire terminal boxes employing jelly locks to make the connection to internal house wiring are more about appearance than anything else. As already stated here, a properly made jelly lock will exclude water very effectively but looks much nicer in an enclosure. Ours is a small black box about 3 by 2 inches and looks the business. I have seen flooded footpath chambers with jelly joints in, and circuits were unaffected. At the pole end, the old grey dropwire number 2 was intended to be terminated under screws without stripping the cable ends using " insulation displacement " technology, but most engineers didn't trust them so stripped back anyway:-)


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