Why would a 4 HP compressor state it needs a 40A supply?

[rcx132]

The compressor is 4HP, 200 litres, Clarke, single phase. Specs say it is 3000 W. Specs also say it needs a minimum 40A supply. At 3000 W isn't 13 Amps enough? My garage is on a 40A supply and has its own consumer unit so I could put in a 40A socket (though I'm only aware of 16A and 32A sockets).

 

[knighty]

inrush current when it's starting up

it'll pop a 13amp fuse in a plug... but it'll be a lot less than 40amps... I think they're just covering their arses for people wanting to run them from a 3pin plug

 

[Robotstar5]

The compressor is 4HP, 200 litres, Clarke, single phase. Specs say it is 3000 W. Specs also say it needs a minimum 40A supply. At 3000 W isn't 13 Amps enough? My garage is on a 40A supply and has its own consumer unit so I could put in a 40A socks (though I'm only aware of 16A and 32A sockets).

The next size up is 63A

 

[brightspark]

wire it in direct and it wont need a plug just an isolator switch

 

[123hotchef]

12.5 amps

 

[brightspark]

starting current will be over 50 amps my 3hp comp is

 

[123hotchef]

that a lot of current

 

[brightspark]

that a lot of current

put on a c type breaker its only a few seconds starting load

 

[rcx132]

Does P=VI work with AC? I.e. if this compressor is 3000 W then current = 3000/230 = 13.0 A.

starting current will be over 50 amps my 3hp comp is

My 3HP compressor only registers 13.0 A on my power meter, doesn't register any starting current. Might just be my meter, it's a digi one, so maybe has a delay.

12.5 amps

13 A at 230v
12.5A at 240v. We're supposed to be at 230v now, as apart of EU unification. Oh wait !

 

[123hotchef]

put on a c type breaker its only a few seconds starting load

my mig was tripping the 16amp breaker today with out even striking a arc would a c curve fix that?

 

[brightspark]

u need a clamp meter that can register inrush current on motors over a few seconds they cant register starting current on 1120v transformers though as the starting current is 2 fast and wont register

 

[brightspark]

my mig was tripping the 16amp breaker today with out even striking a arc would a c curve fix that?

if there transformer based it should do

 

[123hotchef]

if there transformer based it should do

indeed it is

 

[rcx132]

my mig was tripping the 16amp breaker today with out even striking a arc would a c curve fix that?

I think that's what the C curve MCBs are for.

 

[WorkshopChris]

You find they state 40a as it saved them lots of returns from inadequate supplies.

 

[Cobs]

I run a 4hp motor on my compressor on a dedicated blue 32 amp socket connected to a 20A C type breaker. Works fine

 

[brightspark]

my 180 amp oilcooled can knock a 30amp breaker out just on start up no load I'm to lazy to change it from a b type to a c the 110 trannys also trip it

 

[123hotchef]

i just pluged it ino the old ring in the garage on old school re wireable fuse

 

[rcx132]

I run a 4hp motor on my compressor on a dedicated blue 32 amp socket connected to a 20A C type breaker. Works fine

Thanks, that's good to know.

My compressor storage hut has a dedicated 40A supply on a 40A Type B RCBO and I already have a 3HP compressor in there, plus two DIY compressors. I may replace the DIY compressors with this new compressor if I win it at auction. If it doesn't cope then I can look for a Type C, assuming RCBOs exist in type C. I think it's legal to fit a socket on an MCB if it's for a specialist purpose, e.g. compressor, if the socket is labelled as being only for compressor.

 

[brightspark]

providing the board supply the earth there's no need for rcd protection on your compressor just an mcb