What size cable do I need?

[Darkwood]

When I did quick check on specs. It said 75kva total power. Somewhere in there it said 22kw rating

Read all my posts and look what i suspect is the 22kw reference ...please stop picking random suggestiond from domestic installers you are out of your depth big style with your feedback ... no offense learn to swim befor you jump in the deep end

 

[electricshock]

Read all my posts and look what i suspect is the 22kw reference ...please stop picking random suggestiond from domestic installers you are out of your depth big style with your feedback ... no offense learn to swim befor you jump in the deep end

I know you mentioned the 22kw very likely referring to the motor itself as it's a standard size.

 

[Darkwood]

75 kva is just short of 110 amps ... the 22kw is likely the motor reference approx 45 amps .... if the 75kva is the supply demand that is per phase hence 6mm will just melt away ... i cant stress how much this could go ---- up either we have misinformation here or your risking a total cockup ...

 

[Darkwood]

To end this tonight come back with pics of the rating plate or a link to the machine spec.. for installation -most of new machines have online links

 

[shanky887614]

what is the model and make of the machine, that is enough to get the information.

 

[electricshock]

No No Design current equals 1000 x kva divide it by square root 3 x line to neutral voltage.

So that's 75000 divide by 1.72 x 400

75000 / 688 = 109 amps

Grouping factor is 0.79 as there will be 3x 3phase circuits grouped together touching each other.

There is no ambient temperature factor as temperature will be aboutn room temperature and no insulation factor as it will be clipped direct to wall.

It will be protected by bs88 fuses, 1.25 fuse factor


Design current / factors
109amp/0.79x1.25= 110.37 amps

Volt drop can be only 5% of supply voltage for all except lighting which is 3%. So for 400v max volt drop 20volts.

Looking at table 4e4a I will need 25mm cable.


Volt drop for 25mm 3/4 core swa is 0.14 mv/a/m

I estimated about 30metres length so 30x110.37x0.14 = 463.55

463.55/ 1000 = 0.463 volts.

So that's well within the permitted volt drop.

I can't work out shock protection as I don't have ze value.

 

[Darkwood]

I believe I need 6mm cable. But I'm going to get the full specs first.

After your last post and quoting this one how will 6mm cope with this ampage?.... hence my replies!

Regarding your last post ...cable type and install methods are the same with volts drop reg's.
You quote your not sure if bs88's require a derating factor like 3036's?

When you come on the forum without supplying the expected info then giving posts of im 'not sure!' your coming across as been well out of your competent zone ...please listen regardless of other posts you are out of your depth and if your lucky you may wing it but carry on and you will be bitten hard ...Im not your enemy im trying to give you a reality check 'Know your limits'!

 

[electricshock]

After your post and quoting this one how will 6mm cope with this ampage?.... hence my replies!

Sorry. But my college days are all coming back to me. And I never knew cable calcs where so interesting.

 

[electricshock]

Does sheathed multicore pvc insulated come under swa cables?

 

[shanky887614]

Does sheathed multicore pvc insulated come under swa cables?

Look at table 4E4A in bgb

(I think page 384 ish, not sure if its same on phone as ive just had an updated pushed)

 

[Darkwood]

Sorry. But my college days are all coming back to me. And I never knew cable calcs where so interesting.

Really sorry but that reply is worthy of the DIY section ... you clearly haven't done a 3yr course with apprenticeship your replies are getting embarrassing .....My advice is forget this job and work with a competent person for at least 5yrs before taking this route... the problem with industrial is a desperate shortage of Electrical Engineers so they are turning to basic electricians to fill the gap hence why you are way out of your comfort zone ...where you go from here is your choice but ive tried help you then seen your later discussions and now believe your in too deep and should walk away from the job.... this is for an electrical engineer yet you struggle with BASIC cable calc you see in domestic!

 

[electricshock]

Really sorry but that reply is worthy of the DIY section ... you clearly haven't done a 3yr course with apprenticeship your replies are getting embarrassing .....My advice is forget this job and work with a competent person for at least 5yrs before taking this route... the problem with industrial is a desperate shortage of Electrical Engineers so they are turning to basic electricians to fill the gap hence why you are way out of your comfort zone ...where you go from here is your choice but ive tried help you then seen your later discussions and now believe your in too deep and should walk away from the job.... this is for an electrical engineer yet you struggle with BASIC cable calc you see in domestic!

Actually I have done 3 years 2330 with apprenticeship. And cable calcs are hardly needed in domestic jobs that's why I can't remember any of it. I just haven't done a lot of industrial work. But anyway I'm gonna carry on. I won't let anyone say what I can or can't do. It's all a learning process for me.

I will update how it goes. The machine is coming in about 3 weeks. I need to get everything ready by then.

 

[Darkwood]

Actually I have done 3 years 2330 with apprenticeship. And cable calcs are hardly needed in domestic jobs that's why I can't remember any of it. I just haven't done a lot of industrial work. But anyway I'm gonna carry on. I won't let anyone say what I can or can't do. It's all a learning process for me.

Good luck! .... then your running into a brick wall jumping from domestic to this - really wish you could realise that you will have only been trained to a domestic install level this job requires advanced courses in design and engineering and your clearly several yrs away from been competent ....i really hope you sort this out with no comebacks but if you do remember what ive tried to tell you if it does go ---- up well you were warned ....and no insurance will cover incompetence ... so expect a bill for your materials, factory loss on production and loss of business on the strength of it... im shocked how you are so at ease with your circumstances but hey! Its your life we aint trying to tell you what you can or can't do but you did ask for the help .... shame the truth 'reality check' isn't to your liking......

Check those who helped you post count and likes and thanks toll ... we don't get here with crap advice.

Have a good week

 

[D Skelton]

This guy is a menace! He needs physically stopping! He's going to kill someone one day!

electricshock, you are contravening BS 7671 by carrying on what you are doing without being competent to do so. You are also breaking the law as you are contravening The Electricity at Work Regulations 1989; regulation 16.

Stop what you are doing before you hurt someone and get a competent electrician to do the work, as you are not!

I for one cannot believe how so many people on here have helped this fella on his merry way, let alone been civil! I'm all for helping people to a certain extent, but this guy needs an education!!!

 

[electricshock]

Is it possible if someone can check if my calculations are right. Anything I missed. Let's just pretend I'm in class.