FP Cable Is Not Always Suitable

[tazz]

The reason I was taught not to blow in a pot is because the moisture from your breath can dampen the mineral - of which would be sealed in with the compound.

LOL, would soon dry out

 

[trev]

Shanky...are you using a cutting compound or oil when cutting....if you find this messy, old trick from an old sod...is use a candle, just as good, less mess and saves you joist blade

Or a tiny dab of vaseline

 

[shanky887614]

Shanky...are you using a cutting compound or oil when cutting....if you find this messy, old trick from an old sod...is use a candle, just as good, less mess and saves you joist blade

course not, I used an old musicians trick and put a bit of oil from face on first

 

[tazz]

course not, I used an old musicians trick and put a bit of oil from face on first

LOL....well if it saves you blade, go for it

 

[shanky887614]

LOL....well if it saves you blade, go for it

the blade itself had a lot of oil on it when I recieved it, tbh I tend to use 3in1 oil for everything even though I know I shouldn't.

the blade will soon get coated it that after it has been cleaned.

 

[tazz]

Joist blades, ware very quickly, if you use oil, wax or compound anything is fine...but nothing will result is 3-4 cuts, then some really bad snagging and a lot of swearing.

 

[micknew]

The reason you shouldn't blow dust etc out of a pot is because your breath contains moisture which will lower the IR test, obviously.
The moisture will never dry out after the seal is fitted, because it cannot escape.

 

[ipf]

Joist blades, ware very quickly, if you use oil, wax or compound anything is fine...but nothing will result is 3-4 cuts, then some really bad snagging and a lot of swearing.

Use a T bar, then, and a ringing tool....not an alarm for when you've stripped the right amount, by the way

 

[trev]

The reason you shouldn't blow dust etc out of a pot is because your breath contains moisture which will lower the IR test, obviously.
The moisture will never dry out after the seal is fitted, because it cannot escape.

You're going to blow on it (if you're daft enough) for a second or two, this will not give the insulant much moisture at all, any moisture it absorbs will disipate almost immediately.
How much residual moisture is in the air around us at any given time?

 

[ipf]

The reason you shouldn't blow dust etc out of a pot is because your breath contains moisture which will lower the IR test, obviously.
The moisture will never dry out after the seal is fitted, because it cannot escape.

Minor problem, done thousands with a short, sharp blow. Never straight after a brew, though :drool5:

 

[micknew]

You're going to blow on it (if you're daft enough) for a second or two, this will not give the insulant much moisture at all, any moisture it absorbs will disipate almost immediately.
How much residual moisture is in the air around us at any given time?

Quite a bit, try it.

 

[trev]

Quite a bit, try it.

The point is that as soon as you've stripped, the insulant is going to be absorbing moisture from the atmosphere. The tiny little bit from a short sharp blow is irrelevant.
I never blow on it but for a different reason

 

[ipf]

The point is that as soon as you've stripped, the insulant is going to be absorbing moisture from the atmosphere. The tiny little bit from a short sharp blow is irrelevant.
I never blow on it but for a different reason

Understandable.

 

[tazz]

The reason you shouldn't blow dust etc out of a pot is because your breath contains moisture which will lower the IR test, obviously.
The moisture will never dry out after the seal is fitted, because it cannot escape.

So what would you think the main content of potting compound is made of (oil & water perhaps), this is why ir readings are all over the place, until it drys out....!!

 

[stevethesparks]

So what would you think the main content of potting compound is made of (oil & water perhaps), this is why ir readings are all over the place, until it drys out....!!

It doesn't dry out, it cures. It certainly isn't made from water. Once sealed, how would it dry out, how many bottles of unopened water do you see drying out?
Its not like breathing on a mirror where the condensation dries almost immediately, the magnesium powder soaks up any such condensation and would be held there by said compound - as small as it may be. In my book, blowing into a pot is just a no go when making off micc ends.

 

[Guest77]

I am not lying if I say I have terminated thousands of ends, seriously thousands, and I blow the dust out of everyone, I rewired a childrens home 20 years ago in pyro and it is still working fine today lol

 

[Engineer54]

It doesn't dry out, it cures. It certainly isn't made from water. Once sealed, how would it dry out, how many bottles of unopened water do you see drying out?
Its not like breathing on a mirror where the condensation dries almost immediately, the magnesium powder soaks up any such condensation and would be held there by said compound - as small as it may be. In my book, blowing into a pot is just a no go when making off micc ends.

Never heard anything so ridiculous for a long time.....

If your hypothesis were correct, literary every pot ever made off, is sealing moisture into the cable from the time of termination.... Just how hydroscopic do you think the magnesium power is for gods sake?? Are you one of these people that think left unsealed for any amount of time, moisture will penetrate the the whole coil?? I'll give you a clue, it took years (around 6 years to be exact) for moisture to travel a couple of foot in a coil of MICC cable that got left at the end of the garden, semi open to the elements.

Some tap and some blow any mag dust or copper filings out of a pot prior to sealing, one things for sure blowing isn't going to matter one jot, and you can take that to the bank!!

 

[Guest111]

pyro was changed slightly in the early 80's I believe before this the filler was just a powder and it was common to have to leave about 2 foot spare for a termination especially outside as it did absorb moisture reasonably readily,however when it was modified a moisture repellant was added to the mag powder and it absorbed even less moisture,I think iirc that it was quoted as somewhere along the lines of less than 1 inch per week for open pyro in a damp environment and even then the application of a little gentle heat from a gas torch would soon dry this out,I think most of us that have worked with the stuff have blown out pots and not seen any problems.For me the most common cause of failure that I saw was the conductors touching within the pot,the best way to prevent this is careful alignment of the pot and seal and then after crimping to give a gentle pull on the conductors as this will ensure they have not been moved during crimping.

 

[Engineer54]

We were using MICC 240mm singles (Trefoil & N) with ultra high temp seals to supply the emergency power supply side of metro stationS (MTR) switchboards in Hong Kong. The humidity present underground during construction was almost unbearable. Like you would be working in a pair of shorts a hard hat and boots and that's it!! Sweat pouring off everyone, ....To my knowledge, not once did a problem arise from moisture entering the MICC cable during the termination processes, the tails of these cables all being in the region of around 600 to 800mm or thereabouts...

 

[stevethesparks]

I can only say I am a little surprised by the differing opinions. As said in my first post (#58) this is how I was taught, starting in the trade in 1972. Some things stick and this is one of them. Maybe phil d in post 78 has hit upon something that my early teachings stem from, who knows? Maybe its over the top twaddle?
I do admit to having a few blows myself in the past (strictly MICC you understand - nothing perverse), but not often and whether correct or twaddle I would still say it is good practice not to.
I don't think I suggested that the mineral insulation was anywhere near as absorbent as lets say talcum powder - as is isn't, but as said all down to good practice, and am a little surprised that E54 doesn't support that.
Either way, its not important, I haven't made an end off for a good 20 years or so now, but in my early days made them off in abundance. Should I come across an MICC installation before I retire, I shall try and refrain from blowing