Voltage drop and me new workshop.....

[georgetheforge]

Hi guys....

righty ho..... i know one of you guys is a sparky....!!! I'm putting in a new supply to my new workshop obviously i want to get a good amperage and not get too much voltage drop thingy...as its about 35/40 metres away...

I was thinking of running 4 core 6mm armoured would that do the 4th core being a spare live in case i wanna do any garden lighting etc ? I will also do a new earth rod down there as i presume that'd be a good idea....

basically wot i dont want is for the lights to flicker as i weld away...!!

g

 

[Debs.]

I`ve used this little application for my own workshop supply and always find it`s calculations helpful for cable-current limitation and voltage-drops:

http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

*Use the drop down boxes on the page for cable size/type/load and length etc.

 

[Sparkey]

Hi george! you could send a pm to Madkayaker! he's a sparky!
But i think he will show up some time tonight to reply on your question;..

 

[piman]

Hello George,

the fourth core will not be any use so just use three core.

Googled this and came up with 56 amp rated and 7.3milliviolt per amp per metre, so 56 amps at 40 metres equals about 16 volts about 6%. However I doubt if you will be using anything like the 56 amps so the drop will be proportional, 8 volts at 28 amps so it depends on what you are running?

Alec

 

[Welderpaul]

A spare live is useless without a spare neutral and a spare earth.

Need to see about getting a bigger supply into our unit. We're in danger of overloading the 3 phase system at the moment. The streetlights go dim when we fire up in a morning!!

 

[simon718]

how many sets do u have running would doubt it will be cheap to upgrade mate

 

[georgetheforge]

thanks guys.... surely the neutral and earth are common....and not necessarily curcuit dependant, as per your consumer unit, the neutrals all go to a termination bar that isn't split anywhere......

 

[Omniata]

If your using RCD's and the load is unbalanced they'll trip...
They work across live and neutral...

Also if you try to put double the load down one neutral it'll over heat...

Earth it common but again needs to be of sufficient size to cope with, or exceed, the maximum load that is likely to be sent down the cable...

An armoured 16mm² XPLE cable like the one I'm planning to install will allow you to run up to 65A at 40m, that should be enough unless you plan to draw more than 15kW...

 

[madkayaker]

hi george Don't bother using 4 core as it is a no no robbing N conductors. How much kit are you using in garage? Also a photo of supply head will help me work out the cable size. Be suspicious of most of the online cable cals as the values have all changed and they only work out half the story.

 

[georgetheforge]

Hi Mad...

its a brand new mk consumer unit on a 100a overhead supply,

was gonna run an inverter tig, old fashioned arc, maybe a 320a mig, maybe a lathe... but luckily i've only got 2 arms so wont be running it all at once....!! some lighting..... and maybe a pond pump...!!!

is it worth running in a duct do you think for comms etc think i might just pull a cat 5 thro for t'interweb in my shed.......errr hum....!!

 

[georgetheforge]

sorry forgot as it's over head theres a main rcd trip 100amp 100milli amp by the looks of things

 

[madkayaker]

would be worth running a duct but technically comms is supposed to be 150mm from power. and that just leaves the question of why you want interweb in shed. The question about supply was to determine if its TT, TNCS, PME as it alters the calcs. The 10mA main RCD is concerning as that is an indicator of TT especial with over head. Do you have an earth spike?

 

[georgetheforge]

yeah got one out the front.... tt does ring a bell.... unfort the cameras busted....

 

[madkayaker]

in that case then its not a DIY job. Sub mains on TT require real thought and with out measuring ground resistance etc can not really advise cable size.

 

[georgetheforge]

thanks mate,

yeah think it worth having someone round.....

 

[madkayaker]

defiantly TT is unforgiving let me know what they recommend and i can translate!