Question regarding my AM2

[Uplight99]

I have my AM2 coming up next week but something is puzzling me and I’m hoping someone can help me out.

So there is some SY cable coming out of the DOL into the 3 phase motor. From my understanding they provide 4 core SY.

I’m a bit confused as to where I’m supposed to get the CPC from as from my understanding you cannot use the braiding as the CPC with SY cable. The 4 cores will pick up my phases and neutral.

I know someone who just passed his AM2 and he said he used a piranha nut and took a fly lead off that into the motor, which means he used the braiding as the CPC. He passed first time so clearly the invigilator deemed this OK which makes no sense to me as you can’t do that in the real world

Can anyone clarify this for me please?

 

[loz2754]

Hi. A 3 phase motor wouldn't normally need a neutral connection. So your 4 core cable would be L1, L2, L3 and CPC.
Although you're not allowed to use the braid of SY cable as a CPC, it still needs a connection to earth using an SY gland and either a banjo, or an earthing nut.

 

[Dustydazzler]

As above the braid needs 'earthing' but must not be used as a CPC.
I have seen it used plenty times as a CPC but this is not correct and Rough as a BAdgers

 

[oscar21]

Thought SY cable couldn't be used for power and was a signal only cable.

 

[nicebutdim]

Thought SY cable couldn't be used for power and was a signal only cable.

What makes you think that?

 

[James]

What makes you think that?

The “Y” series of cable, YY, SY, CY are all described as control cables.
a bit misleading in my opinion as they can be used for power.
however, they are not listed in the wiring regs and you have therefore got to either prove compliance or list as a departure if you are using them for fixed wiring.
or at least that is how I understand it.

it’s one thing knowing that it will do the job, another thing proving it.

 

[MJPD29]

It doesn’t need a neutral. 4th core will be earth. Make sure to use correct sy glands that they provide you with

 

[Uplight99]

It doesn’t need a neutral. 4th core will be earth. Make sure to use correct sy glands that they provide you with

Thank you.

On the refresher course they said the SY glands are the ones with 2 rings where you sort of clamp the braiding between them. I wasn’t aware there were different glands for this

 

[Uplight99]

Hi. A 3 phase motor wouldn't normally need a neutral connection. So your 4 core cable would be L1, L2, L3 and CPC.
Although you're not allowed to use the braid of SY cable as a CPC, it still needs a connection to earth using an SY gland and either a banjo, or an earthing nut.

Thank you for clearing that up

 

[Aaron b]

Remember to leave the conductors long so you can bypass the contactor for testing, check the order of the phases and swap the wiring back before checking the rotation. They used an old type Schneider one when I done mine and it was wired L3, L2, L1. Of course it makes you a better electrician by making you pay to do the whole section because of that though...

 

[Uplight99]

Remember to leave the conductors long so you can bypass the contactor for testing, check the order of the phases and swap the wiring back before checking the rotation. They used an old type Schneider one when I done mine and it was wired L3, L2, L1. Of course it makes you a better electrician by making you pay to do the whole section because of that though...

We were told to test from DB to the supply side of contactor then test from load side of contactor to the motor for the dead tests. I suppose I could just take them out of the contactor, connect them together and test that way?

 

[Aaron b]

We were told to test from DB to the supply side of contactor then test from load side of contactor to the motor for the dead tests. I suppose I could just take them out of the contactor, connect them together and test that way?

That's how I did it but I can't see why either wouldn't be acceptable.