pdm
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 posted on 29/1/10 at 08:54 AM |
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single phase versus 3 phase
Hi
I have two questions about air compressors please.
In a normal house (well as normal as you get with wife and 2 kids !!) with normal electiricty supply at 240v can I run a single phase or 3 phase
compressor plugged into a normal socket ?
Do I need to worry about ampage and fuses in the fusebox ?
thanks
Paul
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nitram38
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| posted on 29/1/10 at 08:59 AM |
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Only single phase and limited to a 13A plug top, unless you buy a phase converter to create artificial 3 phase.
You can go higher than 13A if you put in a dedicated supply from your fuseboard, but ultimately your supply fuse and current house load is the
limiting factor
Running any heavy motor or welder will cause a volt drop on the rest of your house so expect lights to dip on start up.
[Edited on 29/1/2010 by nitram38]
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pdm
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| posted on 29/1/10 at 09:19 AM |
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Ok thanks
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bodger
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| posted on 29/1/10 at 09:58 AM |
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I'm not an electrician so this may not be completely by the book but this is what I've done & I think it is safe:
If you have a ring main to the garage (2.5mm2 cable looping around your sockets then both cables going back to a 32A breaker in your fuse box) you can
buy a 16A single phase socket & wire that into the loop via separate 16A breaker & then wire a 16A plug on to your compressor. Although I used
an old 16A circuit breaker I think you can get ones that have a delayed trip so they don't react to the surge you get when the compressor first
starts up. I also use the socket for my mig welder. My compressor is quite large, I think it's about the limit for a single phase one, & it
works fine.
Whether or not your allowed to do the wiring yourself these days is another matter. I think you're OK adding to an existing circuit in the
garage but not running a whole new one. I've been a very naughty boy 
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pdm
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| posted on 29/1/10 at 10:04 AM |
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cheers bodger.
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NigeEss
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| posted on 29/1/10 at 11:41 AM |
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I took a separate 6mm T&E from the consumer unit using a 32a breaker.
This feeds to a 16a socket in the garage ( which I use for the welder )
and a 3 phase inverter for the lathe.
[Edited on 29/1/10 by NigeEss]
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Stuart_B
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| posted on 30/1/10 at 04:00 PM |
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as said the on the older motors you can make them work with single phase by wiring them up to do so. it just takes the motor long to start so higher
start up current mean using type c or d breakers instead of type b, but as well you want a bigger enough supply to the gararge.
or even use of capactiors wired up to give artificial run phase.
i only have a 10mm t&e supply from a 40amp breaker. and i have 16amp plug for a few things.
stuart
black mk indy, 1.6pinto on cbr600 bike carb's.
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