need some help with galv trunken?

[steviethespark]

hi,i have to run a leth ot 4inch trunken into a squre d board and i was wondering is it ok to stop it at the top of the board and put a copper bonding strip to earth it,some people say u have to flange it into the board ,not sure what thats means?

 

[Deleted member 9648]

A flange is a fabrication on the end of the trunking which is bolted to the DB....it can be made on site by slotting about 25mm down each corner of the trunking and bending with the aid of a vice to form a flange....alternatively manufactured ends are available.This is a better job than simply stopping the trunking,but as long as earth continuity is maintained either method is acceptable.

 

[nickblake]

the flange is a bracket that fits around the base of the trunking and screws to the board and trunking , but its not always nessesary as long as the trunking is secure and all sharp edges are protected so the cables will not be damaged during installation , you should earth it with an earth cable ,and with the safety electrical connection do not remove attached

 

[steviethespark]

So to make a flange i leave to slots down each side of trunken around 25 mm cut the back off,and bend both sides and bolt them to db,cutting the hole in the db the exact size of the trunken?

 

[steviethespark]

any pics of a man made flange plz?

 

[Deleted member 9648]

I usually use 2 squares of paxolin insulating sheet,one is sat on top of the DB with the flange on top of that,the other is inside the DB,the bolts go through all. Then put a large hole cutter through the centre...you will end up a hole through the 2 squares of paxolin and the DB, the edges of which are about 15mm thick and so form a bushed cable entry.

 

[ecclescake]

I usually use 2 squares of paxolin insulating sheet,one is sat on top of the DB with the flange on top of that,the other is inside the DB,the bolts go through all. Then put a large hole cutter through the centre...you will end up a hole through the 2 squares of paxolin and the DB, the edges of which are about 15mm thick and so form a bushed cable entry.

Total over kill would not use any just buy a flange and jig it out and then use a bit of grommit strip.

 

[Deleted member 9648]

Grommet strip never stays on.....it always comes adrift at some point leaving sharp edges....half a job in my opinion..

 

[malcolmsanford]

I have to admit depending on the size of the board it's either slot or bushes for me.

If it's a substantial 32 way TP & N board I would slot the trunking and board, then board between the trunking and the board. I would cut the board slot about a couple of mm outside the trunking and board slots to give a smooth edge, and then bolt through.

If it's a smaller board or a single phase board then a couple of 2" long bushes and hex nuts for me. Hole the trunking, bush into trunking and fixed with a locking nut to give you gap for putting on the lid. Hole the board and fit, locknut the board onto the bush.

 

[Deleted member 9648]

I have to admit depending on the size of the board it's either slot or bushes for me.

If it's a substantial 32 way TP & N board I would slot the trunking and board, then board between the trunking and the board. I would cut the board slot about a couple of mm outside the trunking and board slots to give a smooth edge, and then bolt through.

If it's a smaller board or a single phase board then a couple of 2" long bushes and hex nuts for me. Hole the trunking, bush into trunking and fixed with a locking nut to give you gap for putting on the lid. Hole the board and fit, locknut the board onto the bush.

Yep...done that as well.....anything but grommet strip.
One thing worth pointing out as well is to always ensure whatever method you use the entry is of sufficient size for all the cables that are ever likely to go into the DB.....Nothing more irritating than a half filled 36 way DB with a large almost empty trunking coming into,only to find an inadequate entry has been formed and i'ts already stuffed.....enlarging it at a later date is next to impossible.

 

[malcolmsanford]

Yep...done that as well.....anything but grommet strip.
One thing worth pointing out as well is to always ensure whatever method you use the entry is of sufficient size for all the cables that are ever likely to go into the DB.....Nothing more irritating than a half filled 36 way DB with a large almost empty trunking coming into,only to find an inadequate entry has been formed and i'ts already stuffed.....enlarging it at a later date is next to impossible.

Ah but that is why nature gave us tallow .................nothing like a bit of tallow, and a few expletives, to encourage another few cables into those nice snug bushes.