Davisonp
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- Reaction score
- 92
Hi,
The background.
A church bought a derelict farm about 4 years ago. They demolished several non listed buildings and put up new wood buildings in their place. A new 100 Amp single phase supply was brought into one of those buildings and a henley block used to supply a local consumer unit, then two switch fuses that supply the two other big buildings.
Non of the new electrical work was certified.
The church need to move one of the buildings supplied by one of the switched fuses and have asked me to disconnect and make safe, then reconnect at it’s new location.
I have had a look and the supply cable to this building is 25mm 3 core SWA, and the building is 100 meters away. The consumer unit had a Maximum Demand of about 80 Amps
I looked at the switch fuse and it is 100 Amp.
Question 1)
My main concern is the current supply cable appears to be undersized. If it is expected that 100 Amps is going to be available for use at the end of the cable, then 50mm SWA should have been used to compensate for voltage drop.
So, Should I be changing the BS88 fuse to a 50 Amp fuse as 50 Amps over 100 meters will meet the voltage drop regulations, or what should I be doing in this situation?
Question 2)
The building is now moving a further 40 meters away from the supply, and they want a supply for building works at the end of the existing 100 meters (32 amp Cform and 16 amp Cform) and I am not sure how to proceed. I was thinking of a henley block feeding a local small cu for the builders supply and another length of SWA to the new building supply. Do I need another switched fuse before the new 40 meter SWA? And, do I calculate the cable size for the extra 40 meters as from the new Henley block, or from the supply 140 meters away?
Any Advice appreciated.
The background.
A church bought a derelict farm about 4 years ago. They demolished several non listed buildings and put up new wood buildings in their place. A new 100 Amp single phase supply was brought into one of those buildings and a henley block used to supply a local consumer unit, then two switch fuses that supply the two other big buildings.
Non of the new electrical work was certified.
The church need to move one of the buildings supplied by one of the switched fuses and have asked me to disconnect and make safe, then reconnect at it’s new location.
I have had a look and the supply cable to this building is 25mm 3 core SWA, and the building is 100 meters away. The consumer unit had a Maximum Demand of about 80 Amps
I looked at the switch fuse and it is 100 Amp.
Question 1)
My main concern is the current supply cable appears to be undersized. If it is expected that 100 Amps is going to be available for use at the end of the cable, then 50mm SWA should have been used to compensate for voltage drop.
So, Should I be changing the BS88 fuse to a 50 Amp fuse as 50 Amps over 100 meters will meet the voltage drop regulations, or what should I be doing in this situation?
Question 2)
The building is now moving a further 40 meters away from the supply, and they want a supply for building works at the end of the existing 100 meters (32 amp Cform and 16 amp Cform) and I am not sure how to proceed. I was thinking of a henley block feeding a local small cu for the builders supply and another length of SWA to the new building supply. Do I need another switched fuse before the new 40 meter SWA? And, do I calculate the cable size for the extra 40 meters as from the new Henley block, or from the supply 140 meters away?
Any Advice appreciated.