Problems starting up compressor

[martlewis]

Hi all,

Having a bit of a problem and not sure where to post but here goes.

My Bandit compressor worked fine until recently when I moved it out into the new workshop. Now it struggles to start, the best explanation is that it sounds like it isn't turning over!? I know of issues running compressors on extensions and power drain or whatever the tech term is.

The feed to the workshop is from 100A consumer unit via 20ft SWA into a 30A consumer unit. From there is a ring main of about 40ft. Anyone on this site electrically minded in amongst all the sawdust that could advise me please? Was wondering if there is anything I can add to compressor to get it to start?

Many thanks,

Martin

 

[Blister]

What HP is the compressor motor

and what amp cable from the 100amp consumer unit to the 30amp consumer unit , also what amp cable round the ring main ?

 

[RogerS]

Martin

Take it back to where it was working and see if it's still OK. If it is then there is something wrong with your electrics. If it isn't then it's the compressor.

Roger

 

[Fecn]

Hi Martin,

A few months ago, I had a Clarke bandit compressor which seemed to have the same problem - In my case, it was the pressure-switch/of/off bit that was causing the problem... Compressor tried to start, and the initial kick caused a loose connection to work looser so the compressor stopped again.

When it happened to me, the compressor was only a couple of hours old... so it went straight back to the shop.

I found that tapping the black control box with the end of a screwdriver got the compressor running for a while.

 

[Fecn]

Hi Martin,

A few months ago, I had a Clarke bandit compressor which seemed to have the same problem - In my case, it was the pressure-switch/of/off bit that was causing the problem... Compressor tried to start, and the initial kick caused a loose connection to work looser so the compressor stopped again.

When it happened to me, the compressor was only a couple of hours old... so it went straight back to the shop.

I found that tapping the black control box with the end of a screwdriver got the compressor running for a while.

 

[davy_owen_88]

If it works fine on the supply at the house end the issue is due to voltage drop. During startup motors draw far more than their rated current which for the bandit is 4.5amps rated current. This causes the voltage to drop if the cable isn't suitably sized and since motors don't react well to undervoltage they may not start.

Did a qualified electrician install the electrics? If so he should have calculated the voltage drops (assuming he knew it was going to be used for a workshop that is).

If you let me know what size cable was installed I can tell you if that is the problem.

Davy

 

[Chris Knight]

Temperature affects mine greatly. Hard to start on a cold morning and often trips the cutout on the unit - a warm day and no problems. I guess the oil thickens up a lot or something.

 

[martlewis]

electrician did the work. he used 4mm swa cable from a 32a rcd in the house by the looks of it.

 

[davy_owen_88]

Have you tried it back in the house to see if it works? Although 4mm^" cable is undersized for a workshop, depending on the other electrical items you have running at the same time it is unlikely that the compressor (1.25HP/1kw/4.3A) is causing unacceptable voltage drop.

Ofcourse the voltage drop is affected by the total current drawn through the SWA so if you had lots of other things on it might be enough to cause problems.

Davy

 

[martlewis]

The only other things on when the compressor tries to start are 3 8ft lights and the radio. Only a very small home workshop and he worked out the loads required. I have since upgraded to a SIP t/s and 1hp dust extractor so maybe need to upgrade the swa.

The compressor seems ok when used in the house but swmbo doesn't seem to want me to keep it running indoors for some reason, some complaint about noise or something :roll:

 

[RogerS]

So have you actually carried it back to the house to try it there as Davy-owen and I suggested?

 

[paulm]

What Davy Owen and Roger said - I had a similar effect when trying to use a different make of compressor in the garden last summer, on an electrical extension lead.

The voltage drop over the lead must have been considerable (it was about 30 m long !), and the compressor struggled to turn over. Back in the workshop it was fine.

Not really relevant to yourself, but I ended up putting the compressor in a wheelbarrow, filling the tank back at the workshop and then wheeling it to the other end of the garden to use till the pressure dropped, then back to the workshop again......... :lol: Worked a treat though !

Cheers, Paul.

 

[davy_owen_88]

Try plugging the compressor in at the socket closest to the garage consumer unit and see if that makes any difference. Voltage drop occurs everywhere until it reaches the appliance, so if you have 6m of SWA and then 10m of twin and earth and then a very long service cable you might well be over the 4% max. for VD.


Davy

 

[martlewis]

I tried it in the house and it worked fine. When he wired he did it as a ring main, running twin and earth right round the shop and back to the cu. Would that make a difference? The socket for the compressor is only about 6ft cable from the cu.

 

[RogerS]

I reckon you've got a high resistance somewhere in our circuit. A connection not done up tight enough.

Have you tried a different socket in your workshop?

My cable is also 4mm to the workshop and my Bandit starts fine..as does my large table saw/bandsaw/spindle moulder etc.

 

[martlewis]

If I get chance tomorrow I'll try a socket the other side of the cu and see if that helps.

 

[Offcut]

Have you checked the oil recently?

Could be low in oil or no oil, the temperature could be a factor.

House warm - Shed cold?


Andy

 

[martlewis]

Just got in from work, not had chance to test another socket yet. As for the oil it is fine.

Martin