“Domestic” Cable for Motor Applications

[Dillb]

To be fair T&E type cable is domestic cable. It's really not designed for non-domestic use. Such use might be described as "value engineering".

Really? I have seen it used in many commercial and industrial installs.

 

[Risteard]

Really? I have seen it used in many commercial and industrial installs.

Value engineered ones.

 

[Dillb]

Value engineered ones.

No just ones where it is suitable for the enviroment installed in.

 

[Risteard]

No just ones where it is suitable for the enviroment installed in.

LOL. T&E cable standards specify it as a domestic cable. I will never accept that it has a place in non-domestic installation.

 

[Dillb]

LOL. T&E cable standards specify it as a domestic cable.

Wheres that then? Any BS standards mention it?

 

[Cadgey123]

You see that white LSF T & E lashed in Commercial projects all over the place.

 

[AJshep]

I'm not sure BS 6004 6242y twin and Earth is specified as domestic cable. But you definitely would usually expect to see it more in domestic settings.
Just like the low smoke version BS 7211 6242b you would usally expect to see more in a public building or commercial type setting.

Both are recognised in the BS7671 as technically better than YY SY cable that are non standard.

 

[Marvo]

We have stock of big sizes of twin and earth up to 25mm sq. From memory it's a single solid conductor up to 16mm sq, after that it has multistranded conductors sao maybe the solid conductor sizes are classed as domestic and the larger multistranded sizes are commercial. I think it might actually be available in sizes even larger than 25mm sq as well.

If the motors are run by inverters or drives or any kind of high frequency modulated supply you should avoid using solid conductor cables.

One limitation with twin and earth can be achieving disconnect times with the undersized CPC. Maybe that's why they class it as a domestic cable in the UK because with longer runs and higher potential fault currents in commercial installations it would certainly be a limiting factor.

 

[IAmSparkytus!]

I would like to know out of curiosity, westward10 - is that unheard of? Might be useful information in the future you never know.

And i’m not sure, just didn’t seem like it was good practice for some reason in my head. Can’t put a finger on it.

 

[IAmSparkytus!]

Each motor unit can be switched on and isolated by the rotary isolator adjacent to it.

Units are connected to the isolators by T&E cable as well.

No solid answers so far as to why it would be a bad idea to use twin and earth other than the install not looking as good as it maybe could have done.

 

[Rpa07]

Disconnection times referring to the undersized CPC in T +E.
Vibration issues in terminations of the final length Rotary to Motor control are the answers picked up from the responses so far.
A J - disconnect times
Marvo - undersized CPC
Everyone else - vibration issue

 

[Pete999]

Disconnection times referring to the undersized CPC in T +E.
Vibration issues in terminations of the final length Rotary to Motor control are the answers picked up from the responses so far.
A J - disconnect times
Marvo - undersized CPC
Everyone else - vibration issue

With regards to Vibration issues, I was one of those who supported that, but what about MICC that had solid core conductors, although Electricians sometimeput a loop in the cable to counter act vibration.

 

[IAmSparkytus!]

No problem with disconnection times and the earths all seem suitably sized. 6mm twin and earth is the largest in place. There has been 2 x 10mm SY cables installed as well where the earth is obviously the same size as the line conductor.

Regarding the vibration issue, unless I’m missing something or not thinking fully, what difference would a stranded core cable make to a solid core cable if both had a nice tight connection? Or is it not the cable coming loose which you are getting at?

Thanks.

 

[Dillb]

The name flexible cable will be the clue here, seeing as the motors will be vibrating a solid core cable is more liable to snap in the termination than a flexible one.

 

[IAmSparkytus!]

Excuse me if I’m being ignorant but what makes you think a solid core cable will snap with a bit of vibration unless the copper had been nicked or damaged?

 

[Pete999]

Excuse me if I’m being ignorant but what makes you think a solid core cable will snap with a bit of vibration unless the copper had been nicked or damaged?

Something that is of solid construction, is more prone to breakages than something that is flexible, especially solid conductors.

 

[westward10]

Any chance of knowing what cable is used for the final connection.

 

[Pete999]

Any chance of knowing what cable is used for the final connection.

Any chance of knowing what cable is used for the final connection.

Post#30 says the same cable as the supply is used to make the final connection

 

[westward10]

So it does Pete I missed that. More to this than meets the eye me thinks.

 

[Pete999]

So it does Pete I missed that. More to this than meets the eye me thinks.

Thinking the same Westy