installing temporary 110v supply for a transformer

[kyranocat]

hi guys could really use some help have been given task on my practical course of installing a temporary supply for a 110 tranny, i am either thinking too much or really thick at getting my head around it, i thought seeing as there is a spare consumer unit in the test rig i would install a 32amp mcb with rcd protection and one socket in 2.5mm2 radial. does this sound like its protected enough i mean with a 110v tranny the current carrying capacity should be enough? or am i stupid?
any help would be appreciated.

 

[Marvo]

What is the KVA rating of the transformer and does it have a fuses on primary or secondary winding?

 

[Golden_Boy]

hi guys could really use some help have been given task on my practical course of installing a temporary supply for a 110 tranny, i am either thinking too much or really thick at getting my head around it, i thought seeing as there is a spare consumer unit in the test rig i would install a 32amp mcb with rcd protection and one socket in 2.5mm2 radial. does this sound like its protected enough i mean with a 110v tranny the current carrying capacity should be enough? or am i stupid?
any help would be appreciated.

What will be the expected demand from the supply?

 

[Marvo]

Start with the load which is the transformer and work backwards to the CU. The transformer size will determine the cable size and the cable size will determine the MCB size in the CU.

 

[spark 68]

32amp mcb with rcd protection and one socket in 2.5mm2 radial.

I would have said 16A MCB for 2.5mm or 32A MCB and 4mm radial, both C-type for the current in rush.

 

[Golden_Boy]

How "temporary"??? is it to be.

 

[kyranocat]

sorry guys all the details given are a 110v portable tranny and a tn cs supply,only required temp for hand tools.

 

[Marvo]

The details are too vague. You need to know the KVA rating of the Tx at least.

 

[kyranocat]

sorry missed it out its 3.3 KVA

 

[kyranocat]

sorry must have missed that 3.3kva

 

[Marvo]

3.3KVA is fine on a 2.5mm cable between the Tx and the CU. A 20A MCB would be appropriate.

If the socket is 13Amp rated it's a bit shy, you could install a 16Amp Euro type socket or it might be better to connect the Tx via a fused DP switch unit or DP isolator. I'm sure one of the UK guys will give you the best option.

 

[Golden_Boy]

3.3KVA is fine on a 2.5mm cable between the Tx and the CU. A 20A MCB would be appropriate.

If the socket is 13Amp rated it's a bit shy, you could install a 16Amp Euro type socket or it might be better to connect the Tx via a fused DP switch unit or DP isolator. I'm sure one of the UK guys will give you the best option.

Unless its loaded right up to its maximum the OP may just get away with an extension cable from a standard RCD protected socket. Always allowing for coiled cables etc.
Come to think of it thats what I use on site most of the time....:smilewinkgrin:

 

[telectrix]

my 3.3kVA site tranny almost invariably trips a 16A type B on switch on surge. a16A or 20A type C is what i recommend, on a 2.5mm radial.

 

[kyranocat]

thanks guys i appreciate the help its already mentioned at the back of the wiring regs for a 20amp breaker on 2.5 mill cable for radial but i just wanted to make sure , i was going to start with design current etc and work it out to be sure but no idea what the wattage etc is gonna work out to unless i assume an approx amount then again its hand tools that need powering unless the cheeky ******* plans on powering a factory with it in which case it seems fine.