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Djlelectrical
Hi All, Right here goes..
I have been asked to attend a Manchester city centre job where I have been asked to wire an upstairs flat which is currently fed from a old rewirable fuse board.. Which is fed with 2.5MM cable which is fed from a three phase board. (Needless to say I won’t be connecting anything to that and disconnecting the feed from the db) the new flat is only to have two circuits – Lights (6a) Sockets (20a) 20 due to the wiring method for this install.
First job.. Condemn the board that is currently feeding the upstairs and advice that they need to supply the upstairs flat from another source.
They currently have a single phase board which is used to power the lights and sockets in the shop ( Light use as after putting everything on and using a clamp meter its barely pulling 15a) The unit is fed using 16mm meter tails and wired directly into the 3 phase db. This unit is directly under where the CCU is to be fitted in the flat.
What I am proposing is downgrading the 100a main breaker currently used on the single phase board (Fed straight from Main 3phase board) to a 40a and then installing an additional DB in the flat upstairs again using a 40a fuse on the same 16mm tails, Thus limiting the max current pulled to 80 and therefore keeps the max current under the limits for 16mm tails.
Now then.. Making sure the phases are balanced…. Before I start the current pulled from each phase will be checked and recorded accordingly, Making sure that the extra demand will not affect the balance of the phases. However at what point would you say the system was unbalanced? The system can be checked prior to the install however at the time they could be balanced later in day this might not be the case. Is there a tolerance you can use or what would be a sensible figure to use when determine whether the system is balanced?
The customer was advised that a new supply cable should be installed, However as the run required was 50+ meters (Due to Nicely decorated restraint) from board to flat they refused to pay the cost of the cable to supply the new board
On another note.. After seeing the condition of takeaway kitchens I’m thinking the wife’s cooking is not that bad after all!
I have been asked to attend a Manchester city centre job where I have been asked to wire an upstairs flat which is currently fed from a old rewirable fuse board.. Which is fed with 2.5MM cable which is fed from a three phase board. (Needless to say I won’t be connecting anything to that and disconnecting the feed from the db) the new flat is only to have two circuits – Lights (6a) Sockets (20a) 20 due to the wiring method for this install.
First job.. Condemn the board that is currently feeding the upstairs and advice that they need to supply the upstairs flat from another source.
They currently have a single phase board which is used to power the lights and sockets in the shop ( Light use as after putting everything on and using a clamp meter its barely pulling 15a) The unit is fed using 16mm meter tails and wired directly into the 3 phase db. This unit is directly under where the CCU is to be fitted in the flat.
What I am proposing is downgrading the 100a main breaker currently used on the single phase board (Fed straight from Main 3phase board) to a 40a and then installing an additional DB in the flat upstairs again using a 40a fuse on the same 16mm tails, Thus limiting the max current pulled to 80 and therefore keeps the max current under the limits for 16mm tails.
Now then.. Making sure the phases are balanced…. Before I start the current pulled from each phase will be checked and recorded accordingly, Making sure that the extra demand will not affect the balance of the phases. However at what point would you say the system was unbalanced? The system can be checked prior to the install however at the time they could be balanced later in day this might not be the case. Is there a tolerance you can use or what would be a sensible figure to use when determine whether the system is balanced?
The customer was advised that a new supply cable should be installed, However as the run required was 50+ meters (Due to Nicely decorated restraint) from board to flat they refused to pay the cost of the cable to supply the new board
On another note.. After seeing the condition of takeaway kitchens I’m thinking the wife’s cooking is not that bad after all!
