New wiki article: Terminating MICC / Pyro

[Dave Plowman (News)]

After much bollock scratching I've manage to upload a few pics. Please hurl the usual derision.

[Cicero]

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Bicycle pump - also pretty good for clearing dust from computer internals.

Cic.

[Phil Addison]

Further browsing of that site reveals some nice exploded illustrations of the gland assembly on page 12 of

and an

8-step Terminating Procedure on P13.

Also on P13 is a cross-section drawing of an assembled gland/cable. This shows that the spacing of the two bare wires increases as they pass through the gland seal, and the seal itself does NOT guarantee separation of the wires within the gland, so Dave's step of pulling them straight (but splayed out a little) is worth emphasising.

Actually, wouldn't it be better to put that step at the beginning of "Fit the seal" rather than the end, so you can still see if the wires are straight or not in the critical area where the seal will go.

Phil

[John Rumm]

Ah, that's better ;-)

Now reading between the lines, and comparing your pictures to those on the TLC web site; I would guess that your pots are designed to be used only with a gland since they don't include any explicit way of making an earth connection and one would have to rely on the mechanical clamping of the gland to a conductive box, or the use of a piranha style backnut to get the earth connection (as with SWA). Whereas the ones pictured on the TLC site:

soldered on tails for the purpose...

(talking about said picture - any idea what the black round thing on the left is?)

[Dave Plowman (News)]

You don't need anything other than a straight pull as the seal has quite long tubes on it so they can only go in one direction. See the latest pics. I also mentioned marking the pot with the position of the wires so you don't introduce a twist. Also why I emphasised being careful removing the scrap sheath - even with the correct tool it's possible to twist the conductors together.

[Dave Plowman (News)]

Yes. Never actually used those but knew they existed.

My assumption was that most here would likely use pyro in something like a conservatory etc with bare brick walls. In which case switches and sockets etc would be steel surface mount. Or BESA box fittings. But I can't see anything against soldering an earth wire to the outside of a pot

- before fitting it - or using a clamp on the sheath - if the termination is used elsewhere.

I remember ages ago installing a 2H16 riser on a house conversion to flats where it had (practically) to be surface mount and this was the neatest solution. And work hardening was something else pulling it through a tortuous route. So it just had to be jointed at one point. Made a very neat job using a BESA box - but the LEB inspector insisted on an external earth bond between the sections, even although it tested perfectly.

Not a clue. Weird.

Wonder how old the pic is by the sleeve colours? Mostly terminations come (came) with just black sleeving so you had to identify them afterwards.

[Phil Addison]

Solder alone on a surface does not make a sound mechanical joint, it can easily be torn off, which is why the ones in the TLC pic are (or appear to be) soldered into holes drilled through the pot. Would be even stronger if the ends were splayed out in a countersunk hole where we can see the solder.

Phil

[Dave Plowman (News)]

IMHO soldering a piece of 1.5mm along the length of the pot would be plenty strong - it's not going to be subject to any stress once installed. But you could use a clamp instead.

[Phil Addison]

In a straight pull, yes, but if there is any peeling action it wouldn't stand a chance, even if they managed a perfectly soldered joint on that chunk of brass. I'm pretty sure unaided solder is against some reg or other, it was certainly bannned by Engineering and QC where I worked.

I would just mention the clamp option - anyone that's good enough at soldering can make their own decision to do otherwise.

Phil

[Dave Plowman (News)]

Don't think so. If anyone needs a termination with earth wire these can be bought - as John described

I'm quite happy 'inventing' such things for my own use in my own place - but wouldn't recommend it in such an article. I think I'm already pushing my luck by giving a method to fit the termination without using the special tools. Remembering dribble and the hacksaw...

FWIW, I've never really come across a situation where such an earth wire is needed. If the feeds to your pyro installation are in TW&E, use a BESA box as the JB, and connect the TW&E earth to that - there's a threaded hole provided for an earth screw.

[Phil Addison]

Agreed, I was just picking up on the bit where you said you could use a clamp instead.

Fair enough, and me to :)

Not at all, I found it really useful - I have a small garden workshop on my wish list and I'm now in a much better position to weigh-up pyro as an option to get power out there.

Indeed, but did you look at page 13 of

Phil

[Dave Plowman (News)]

It was only really for interest. Don't expect many to make use of it.

To get power to an outbuilding I'd say SWA a better option. And cheaper, as well as more readily available. Inside the workshop, my choice would be steel conduit and steel surface mount accessories.

Pyro has largely gone out of use because there are easier and cheaper alternatives. As I said at the start of the article it's only really worth using for cosmetic reasons in most domestic situations. Like running across an exposed oak beam. Or brickwork in a conservatory, etc.

[Phil Addison]

Whoa, I didn't say pyro's my chosen option!! You've helped me decide NOT to choose it, LOL. It's marketed as a fireproof cabling system which it does appear to excel at.

Phil