AM2 Help

[kiwilee]

Hello all!

First up I'd like to say what a great forum this is.

Let me introduce myself, my name is Lee & Im an apprentice electrician on the Isle of Wight, I've almost finished my time as an apprentice & got my AM2coming up soon.

So i've been looking around this site for a few months now to gather up some info about it & what to expect. I have come across some helpful posts, Barge, Andy & sparky 999 spring to mind.

So I was hoping if anyone out there could tell me, with the M.I circiut, I know the outer sheath is to be used as the earth, and I heard the pots they give you to use dont have a earth conductor on them

So does this mean that you have to use a banjo at either end of the M.I cable as you do with the SWA? .

Or is the M.I earthed via the chassis of the D/B, is this a sufficient enough earth?.

Sorry if this sounds like a dumb question!!, I like most sparks out there just dont get to work with the stuff. So I am unsure!

Thanks people I hope you can help

Cheers

Lee

 

[Zeespark]

Hia Lee,

Just a quick question, have you undertaken a pyro termination at all? The reason I ask is that what I am about to say will make more sense if you have.

An MI cable more often than not uses its sheath as CPC, though using a seperate conductor for earth is not unheard of.

Once the outer sheath is stripped back, the pot that you install with an olive (colleges like to reuse MI gland packs so dont install the olive) the olive then provides the earth continuity, or you could use the fly lead specially designed for MI pots.

Hope this helps Lee, any other info you are after just shout.

AndyGuinness

 

[Andy™]

the pyro ends dont have the flying lead attached. you just terminate onto DB and thats it - no banjo's like the SWA

 

[Evans Electric]

Welcome to Forum .

Long time since I was in college Kiwi , so I assume you have to make off a pyro end for the exam / test. ? As said above , the sheath is always the earth, the glands & L/nuts have to be tight. Tips when making ends off is when you screw the pot on ,(a) stop when cable sheath is level with bottom of the pot, (B) a small torch is good to look into the pot to make sure there is not a spiral of brass from the thread, shorting out the cores. ( Seen it 100,s of times) © don't blow into the pot before pushing the compound in (moisture) and (d) push in compound from one side only to prevent trapped air, keep stick of compound in pocket if weather is cold.

Oh and the most common apprentice cock-up is to make off an end, all very nice , then notice that shroud has been forgotten. We all did it. I assume its PVC covered.

So, Slide shroud on first, then gland, then screw on pot, check for spirals,slide the seal down the cores to keep them from twisting, take compound from pocket and fill pot slightly higher than rim, push seal down, clamp it up with the crimping tool making sure you don't let it twist the pot, slide PVC sleeving onto cores and megger it on M/Ohms .

Deke

 

[kiwilee]

Hi guys!

Geez! thanks for the quick replys.

Yes! Zeespark i've done M.I terminations before, done a few on the Am2 refresher, and have been practicing recently, but never done them in anger before, so as you said, never terminated with the olive before.

Thanks evans for your M.I termination pointers I shall print em off & take em into account.

Thanks also Andy! so no need for banjos then, just terminate at D/B & TP&N isolator, lock nuts tight , glands tight with olive fitted. And this will provide the earth continuity

 

[oldtimespark]

Hi did have a video on termination of micc (Pyro) will try to find it and no its not Betamax if I do will ask admin if it can be uploaded more info at this link it goes to tycothermal they now own Pyrotenex by the looks of it.