3 Phase Cable

[Tungsten Sharpener]

Earthing on SY braid is a secondary protection to the main cpc, i always tie it in to the earth, if there is mechanical damage which causes a short between a conductor and the braid you will get a trip and avoid a possible danger. Belt and braces.

TS

 

[madkayaker]

defiantly especial when you think SY is used in very harsh environments

 

[theoss]

for SWA you have to work out the earth size needed through Adiabatic Equations or there is charts out there.

Someone did all that on a paper elsewhere, that's where the 95mm comes from, what this bloke deduced..

I might still have it if anyone would like it.

 

[madkayaker]

i have the table from the NICEIC somewhere in my highly organised bomb crater. Would be worth posting on here if you could

 

[theoss]

It was sent to me as an email, not sure if I can post that up in that format?

For the first time ever, I have installed SWA today without an earth core... farmer had some 2 core in a pile... can we use that he said...

 

[madkayaker]

i was doing a farm job tonight 4x4swa and for the first time using a RCD for fault protection instead of trying to get low enough ZS for a D type

 

[theoss]

i was doing a farm job tonight 4x4swa and for the first time using a RCD for fault protection instead of trying to get low enough ZS for a D type

Drifting the topic I suppose...

I love agri work.

I assume it might be feeding a motor if you have a D type? We had issues with suppies installed by others through RCDs last year as we were wiring grain driers and the inverter kept blowing the RCD (installed due to being a TN supply, which took a lot of the farm out...

 

[madkayaker]

no its the feed to my new unit and stick welder. Not heard of inverters tripping RCD but i can see issues with all the electronics in them. Farms have supposed to have a 300mA RCD for the whole installation but most haven't. Went to one job to change a motor and reported to farmer that the new installation hadn't got one and the NICEIC firm that did the job turned round and said that the RCD would INCREASE the fire risk!!

 

[theoss]

it's a leakage thing... invertors naturally lead to earth and my guess was that was the problem... never heard the conclusion though, But basically when the fans were running or starting, there was a risk the RCD would randomly trip...

SO it is either invertor problem (or it's choke)

RCD too sensitive ( I tested it)

Or RCD not appropriate for this application

 

[madkayaker]

it could just be that the inverter leaks that amount and the cumulative effect of the motor also leaking etc was to much. Farms are a bit Leakey at the best of times. Harmonics can play hell with RCD as well.

 

[theoss]

it could just be that the inverter leaks that amount and the cumulative effect of the motor also leaking etc was to much. Farms are a bit Leakey at the best of times. Harmonics can play hell with RCD as well.

Aye, I was a bit suprised the installer didn't think of discrimination and inconvience to suppy and all that... but I was just a doormat subbie

 

[madkayaker]

it take skill and knowledge to do farm work there is lots of variable. Most of the lads doing the electrics ain't much brighter than the stock but some are very good and worth there salt

 

[theoss]

it take skill and knowledge to do farm work there is lots of variable. Most of the lads doing the electrics ain't much brighter than the stock but some are very good and worth there salt

I must be crap then cos I am selling up due to lack of work having not had a proper contract since late November.

But agri is hard, if you try to follow every reg on a smallholding you would be there forever hence bankrupting the farmer... but this place today had a TE running around a pig unit and stuff was rottern. Everthing you touch just breaks.

 

[madkayaker]

you just have to do your best with what you can.

 

[simon718]

and with the limited funds the farmers are willing to provide

 

[madkayaker]

tight buggers.

 

[Luke]

The drive itself shouldn't leak to earth, but any choke or filter will. often, drives have built in filters, which would then make the 'drive' appear to leak.

 

[BILLMJM]

can some one help me i have a soenen hendriks 3 heand welder for makeing upvc windows it is 8.5kw and 32amp 3phase and i want to run of a generator

what size generator do i need
thank you

 

[madkayaker]

17kva would be my recomendation