Wiring for a compressor
- Thread starter dunny
- Start date
Sponsored Links
I'd rather listen to the compressor.
Hee hee
I too would rather listen to the compressor!!What do you think of swapping out CU though?
Thanks
D
The CU could do with upgrading, but it depends on what is happening down the line... if a rewire is planned then its a false eccomony to fit a new CU to the existing installation, fix problems to allow RCDs to hold in etc.
The point behind my comment in jest was aiming at, what is eventually going to happen to the compressor? My suggestion of a board in the garage was based on it being a small workshop, you could have this area sorted out and then not have it touched during the re-wire of the rest of the property, but if its to become a lounge then that changes things somewhat... you do not want a sub-board on the wall above your television!
The point behind my comment in jest was aiming at, what is eventually going to happen to the compressor? My suggestion of a board in the garage was based on it being a small workshop, you could have this area sorted out and then not have it touched during the re-wire of the rest of the property, but if its to become a lounge then that changes things somewhat... you do not want a sub-board on the wall above your television!
Sponsored Links
The whole thing (workshop) will move to another building so the compressor wiring would all just be removed. There is a heap of work to do in the conversion anyway so this in itself isnt an issue. Your point about havng to solve a load of issues after putting in a new CU is a good one though, I hadnt thought of that. As noted earlier there are some sockets on light circuits etc so I assume there is a good chance that things will trip a lot!!
D
1) You could do as planned then, and have a board in the workshop fed off the switchf use, and when the time comes to move compressor. Have the board moved along with it in what is to the the new workshop. And a new submain laid in from the switchfuse that is already present. One could even pre-empt this by having much of the installation to the workshop mounted on a piece of 18mm ply on the wall (ideally stood off it to avoid damp)., When the workshop is moved, the ply goes with it to the new one!
2) The other option I could see, would be to replace that MEM switchfuse with a new CU, with plenty of spare ways. Feed the two existing CUs on 40/50 AMP breakers, not on an RCD. When the re-wire goes ahead, the circuits can be added to the new board and the old boards can be cut off
2) The other option I could see, would be to replace that MEM switchfuse with a new CU, with plenty of spare ways. Feed the two existing CUs on 40/50 AMP breakers, not on an RCD. When the re-wire goes ahead, the circuits can be added to the new board and the old boards can be cut off
Option 2 looks like a good option partly because I have 1 room finished in the house but the sockets in this room are really ropey, e.g. 2 cables in the double socket but one has melted through at some point and is now completely disconnected. I could put in the start of a new ring in this room only and add that to the new CU. I could leave a loop ready to extend the circuit when we are ready. Is it acceptable to bring cables up from under a sub floor to a socket? I can ccess 3 walls from behind but one is the outside wall and now its all decorated I wouldnt want to disturb it all.
I think I will get tthe spark to come out and do option 2 but add a new partial ring manin that can be extended later.
Thanks
D
I think I will get tthe spark to come out and do option 2 but add a new partial ring manin that can be extended later.
Thanks
D
- Joined
- 27 Jan 2008
- Messages
- 24,928
- Reaction score
- 2,884
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
Each motor will take around 13A running depending on efficiency so to run you could likely work on a 32A fuse the problem is with starting. Using an inverter instead so reducing the inrush then it is possible you can run the compressor on a smaller supply. However from what you have said you have already got the compressor with a single phase motor. As to if you could swap for three phase or another compressor with smaller motor I don't know?
Compressors are odd beasts in that you need some method to deload the motor when starting. One would need to very carefully select a inverter which had the outputs to control the deloading. It will not be an easy job however you go about it. Even in industrial premises installing a compressor is not easy. One large problem is heat. All compressors produce heat so it is common to put them outside in a lean to reduce both noise and heat. In some cases there are arrangements to use the heat for heating the building.
Normally we do the planning before we buy anything. Although I have know where some one has built and ordered equipment without thought on place built 4 showers in a block fitted 4 x 10kW electric shower units then asked me to wire them up. They did not like my answer mainly as they had to admit to some one higher up they had made a mistake.
So what you need to do is work out best way around the problem. It may be down to simply only running one motor, it may be inverter drives, it may be loads of new wiring. You have to price up the options and decide which road to take. Maybe even petrol or diesel motors?
Oh just to clarify an inverter normally drives a three phase motor even when the supply to the inverter is single phase. Often small three phase motors are 400 volt star and 230 volt delta so they are configured to delta to run on an inverter on a single phase supply. The inverter has the ability to change the frequency so it starts slow and builds up speed more genitally than other starting methods. This also means less of a dip when the motor starts in the mains voltage. I have not seen an inverter used with a single phase motor. Also 4 HP = 3kW.
Compressors are odd beasts in that you need some method to deload the motor when starting. One would need to very carefully select a inverter which had the outputs to control the deloading. It will not be an easy job however you go about it. Even in industrial premises installing a compressor is not easy. One large problem is heat. All compressors produce heat so it is common to put them outside in a lean to reduce both noise and heat. In some cases there are arrangements to use the heat for heating the building.
Normally we do the planning before we buy anything. Although I have know where some one has built and ordered equipment without thought on place built 4 showers in a block fitted 4 x 10kW electric shower units then asked me to wire them up. They did not like my answer mainly as they had to admit to some one higher up they had made a mistake.
So what you need to do is work out best way around the problem. It may be down to simply only running one motor, it may be inverter drives, it may be loads of new wiring. You have to price up the options and decide which road to take. Maybe even petrol or diesel motors?
Oh just to clarify an inverter normally drives a three phase motor even when the supply to the inverter is single phase. Often small three phase motors are 400 volt star and 230 volt delta so they are configured to delta to run on an inverter on a single phase supply. The inverter has the ability to change the frequency so it starts slow and builds up speed more genitally than other starting methods. This also means less of a dip when the motor starts in the mains voltage. I have not seen an inverter used with a single phase motor. Also 4 HP = 3kW.
Typo/autocorrect fail of the year so far goes to Eric!
Even without the new stuff, is that not a 60 amp maximum switchfus, for the whole house
Even without the new stuff, is that not a 60 amp maximum switchfus, for the whole house
So a new CU replacing this switch is best approach?
D
If it is 60 amp, i may be wrong, did they make a 100 amp version.
Anything after that even a new CU would be limited to 60 amp, a new CU could possibly make that redundant and removable.
If the plans to keep that for now, then the new stuff would need to connect prior to that switchfuse possibly via henley blocks.
One decent Cu could eliminate all that and may be the best option long term, the loads you plan, get a good quality make.
Last edited:
How big can you go with a CU? Could I, for example, have 48 ways or is that just daft?
Do you then have to add up the ratings of all of the individual fuses and ay uner 100A or is it the loadings that is important?
Trying to work out what I should ask the spark to do as opposed to just get the compressor wired in.
D
Do you then have to add up the ratings of all of the individual fuses and ay uner 100A or is it the loadings that is important?
Trying to work out what I should ask the spark to do as opposed to just get the compressor wired in.
D
Some do opt for 36way or 48way 3 phase boards, then fit a single phase kit, so that it can be used on 1 phase, but a bit over the top.
Your still limited to your main fuse "Black one" which though says 100amp may bo only 60a or 80a ( dont attempt to check !)
Your still limited to your main fuse "Black one" which though says 100amp may bo only 60a or 80a ( dont attempt to check !)
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
