Rcd Protection For Supply To A Transformer On Construction Site?

[silver surfer]

Providing 10kva 400v/110v transformers on site and not sure if i need to protect the SWA feeding the TX with RCD.
Comments please.

 

[Marvo]

I don't know what the UK regs say about it but it would seem a pointless exercise and unnecessary expense.

 

[IQ Electrical]

Providing 10kva 400v/110v transformers on site and not sure if i need to protect the SWA feeding the TX with RCD.
Comments please.

There is no specific requirement in 704.

 

[davewdave]

what if the live cable falls out and touches the casing of the tx

 

[telectrix]

bang....

 

[davewdave]

ha.....so an rcd would come in handy then

 

[derek]

What do you think people used before RCDs were invented?

 

[itselectric]

The way I look at it the TX is an item of equipment so it needs to be fed safely. If the circuit calls for rcd protection then it should be used, before rcd's was also before 11ov on building sites and a lot of accidents happened, thus the implementation of transformers.
If the feed to the transformer is in another building then, if following regs an rcd should be fitted. thats the way I read it anyway.
I've got my blindfold on I've smoked my last cigarette, so fire away.lol

 

[davewdave]

do you get 110v from + and - ....or still only 55v.....................would you protect the transformer mcbs with an rcd, if so how would you test the rcd protecting the 110 circuits

 

[Knobhead]

As RoB suggested in you're other thread. Get someone that knows what they are doing, before you kill some innocent schmuck.

 

[telectrix]

think it's a hypothetical thread, tony. OP was nearly 2 years ago.

 

[davewdave]

i dont think you know what your going on about

 

[davewdave]

if you had an rcd protecting the aroured feeding the tx, and there was an earth fault on the 110 yellow cable would this trip the rcd

 

[UKMeterman]

As a site transformer should provide isolation between the primary and the centre earthed secondary, I will let you sketch the earth fault current and then present an answer.

 

[davewdave]

the l n are seperated but the earth flows back to source....so no.....so if the cable going into the tx is terminated into an rcd this is also primary side and also would not trip if same senario

 

[davewdave]

so ive found out that you can test at 55v and the rcd should be on the secondary side and the rcd really should be designed for 110 use, i got there in the end and all the doubters abviously didnt know this....thanks for the pro active comments, all i need to find out now is exactly how you test it

 

[ARK]

i had this the other year, rcd is not required, i had to resort to nic helpline to be sure lol

 

[davewdave]

is what i am saying right tho ark.....what situation did you have

 

[ARK]

yes you are right mate, its seperated so no point ot it,

 

[davewdave]

you can buy megger rcd testers that let you test 110v cte, and it enables longer lengths of cable curing efli measurements......not sure how effective they are as additional protection......or how you would test the 110v rcd....i suppose using the prongs on the l e and n at end of female plugs........i can understand protecting the armoured with an rcd as the breaker is 50a in my case, but i cant get an rcbo that size.....only saying this as its an electrical forum and if i said this to my mrs she would leave me....---