Compressor states 40amp supply is required?

[flanajb]

Looking at a large compressor, and the spec states a 40amp supply is required. The supply to the garage is protected with a 40amp breaker on the non RCD side of the house CU. Just trying to work out why it's 40 amps and whether it will always draw 40 amp every time is kicks in. This will mean I will overload the system should I happen to be using the PT or Table saw.

Anyone got any thoughts here. 40amp for a single phase unit sounds a lot.

 

[OLD]

I think you are correct it will trip the breaker start up current under load is very high for a instant until the motor starts to move . If the feed cable is thick enough then its a breaker uprating job if not then a new feed cable say 2.5mm ( gives 27 extra amps ) in parallel with the existing will uprate the supply for lowest cost

 

[flanajb]

I think you are correct it will trip the breaker start up current under load is very high for a instant until the motor starts to move . If the feed cable is thick enough then its a breaker uprating job if not then a new feed cable say 2.5mm ( gives 27 extra amps ) in parallel with the existing will uprate the supply for lowest cost

Do you happen to know what the maximum amperage is for 10mm2 and 16mm2 armoured cable?

I know this depends on the voltage drop from the house to the garage, but will enable me to calculate whether I can just upgrade the breaker or whether the compressor is a no go.

 

[flying haggis]

1omm swa is 85amps capacity and 16mm is 110amps as you say it depends on volt drop and also distance

http://www.tlc-direct.co.uk/Technical/C ... eDrop.html

 

[flanajb]

1omm swa is 85amps capacity and 16mm is 110amps as you say it depends on volt drop and also distance

http://www.tlc-direct.co.uk/Technical/C ... eDrop.html

I had a look at that site earlier, but unfortunately, it does not tell you the max amperage for a given cable size / distance, but instead the required cable size for the given kw you want.

 

[OLD]

Current rating :- approx 4.2 amps equals a kW. also 746 watts equals a horse power so you can calc kW for the above TLC calc.

You can Google current rating, how the cable is installed and there for its ability to loose heat is a factor on current rating.

 

[flanajb]

Looking at these links and messing around with the voltage drop, a 10mm SWA cable installed underground with a 30M run has about a max amperage of ~ 45

The compressor requiring a 40 amp supply is quite close to the limit?

 

[flying haggis]

does this compressor require a run current of forty amps because if it does that is going to be one hell of a leccy bill to run it! or is the 40 amps just a start current, do you have any pics/details of the unit

 

[flanajb]

does this compressor require a run current of forty amps because if it does that is going to be one hell of a leccy bill to run it! or is the 40 amps just a start current, do you have any pics/details of the unit

https://www.machinemart.co.uk/shop/prod ... compressor

It's a 4HP motor, but I assume it's just for the start current

 

[finneyb]

Are you sure you want this compressor ' It is recommended that this air compressor is fitted with heavy-duty anti vibration floor mountings .... ' ' When fitted to the legs of the air receiver, they can often help reduce noise and vibration. '

Often help !!!!!! reduce noise - no certainty there then. I may be getting sensitive in my old age but if heavy duty anti vibration mountings only often help reduce noise I wouldn't want it same building I was in.

Just my sensitive 2p's worth

Brian

 

[Myfordman]

you could well need a C40 mcb fitted in the CU to prevent tripping.

 

[flanajb]

Are you sure you want this compressor ' It is recommended that this air compressor is fitted with heavy-duty anti vibration floor mountings .... ' ' When fitted to the legs of the air receiver, they can often help reduce noise and vibration. '

Often help !!!!!! reduce noise - no certainty there then. I may be getting sensitive in my old age but if heavy duty anti vibration mountings only often help reduce noise I wouldn't want it same building I was in.

Just my sensitive 2p's worth

Brian

I have a good pair of ear muffs. I might need to distribute a few pairs to the neigbours

 

[flanajb]

you could well need a C40 mcb fitted in the CU to prevent tripping.

I already have a 40 amp MCB fitted in the house CU, but I suspect that if I have the lights and heater on when I fire the compressor up it will cause the mcb to trip?

 

[woodfarmer]

I installed 6mm armoured cable to run my 5.5 hp log splitter motor. It is good for 53 amps up to 50 metres. without much voltage drop. I bought it from here and they were both helpful and efficient. be aware it is heavy Mine is buried across the yard from house to barn, when you lay it, zig zag it in the trench so if a heavy vehicle runs over it when the soil is wet and soft it has some slack and wont tension the cable , just straighten out the zig zag a little.

http://www.tlc-direct.co.uk/Products/SW6slash3.html

regards

 

[OLD]

Just a suggestion have a look at my post using two compressors which you could arrange to only switch on the second for heavy air requirement so ok for number one to auto cut in while using a machine.I would say that my choices do not have the machine quality you were proposing but there are lots of compressors to choose from.

air-compressor-what-to-buy-t85823.html

 

[Myfordman]

you could well need a C40 mcb fitted in the CU to prevent tripping.

I already have a 40 amp MCB fitted in the house CU, but I suspect that if I have the lights and heater on when I fire the compressor up it will cause the mcb to trip?

Are you sure it is a type c breaker?? Most domestic Mcb are type b