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SIP Compressor blowing breaker long before pressure is reached.


Colin Lindsay

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  • 3 weeks later...

...and just to adjust the above, slightly, it now hates plugs too. 30 minutes sandblasting today saw it shut off and not restart, so once again I had to start at the pressure switch (just replaced with a new unit as of a fortnight ago) and work back to the plug, which looks like this:

6162F7CC-9B38-4486-B04B-6F39436BCEBA_1_105_c.jpg.10099ef96a0df2cacc2a1eed3d3dd35a.jpg

The resistance now appears to be at the plug end, not the motor. I'm starting to get seriously peed off with it.

 

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Hi Colin,

 That should never happen. Suspect, there is damage to the socket as well?

To move on: Get a proper BS1363 plug, BS1362 fuse & a new quality socket.

And wire the new plug checking all is tight. Fold over the wire in the plug contacts if you can. Make sure you do not damage the conductors when stripping. 
Use the strain relief on the outer conductor, not the wires.

Cause? I need to see a closer picture of the plug.

If you follow the above it will not happen again.

Have fun,

Iain.

 

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Hi,

 If the CSA of the cable is >1.5mm2 you should really use a BS60309 plug & socket. 2.5mm2 in a BS1363 plug will not cause a problem it is just a fail if it was ever PAT tested.

BS60309 plugs do look more pro & capable of 16A. If you were pulling more than the rating of the 13A BS1362 fuse it should have just blown & not tried to burn the garage down.

Cheers,

Iain.

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Commando plug is the commonly used name.... I am not sure what area of electrical work you are in (big commercial?) but domestic and small commercial users would use commando.

Colin, that plug is a liability. Looks to be a cheap and nasty plug, clamped on the conductors not the outer sheath and so on. The live conductor looks like it may have suffered damage? Or maybe a loose screw terminal?

Cut the cable back a bit and a quality plug should see you back up and running. But  dedicated 16A breaker and a commando plug/socket setup would be preferable.

 

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16 minutes ago, clive said:

Commando plug is the commonly used name.... I am not sure what area of electrical work you are in (big commercial?) but domestic and small commercial users would use commando.

Colin, that plug is a liability. Looks to be a cheap and nasty plug, clamped on the conductors not the outer sheath and so on. The live conductor looks like it may have suffered damage? Or maybe a loose screw terminal?

Cut the cable back a bit and a quality plug should see you back up and running. But  dedicated 16A breaker and a commando plug/socket setup would be preferable.

 

+1

The term "Commando" in this context is actually a trademarked name of the MK Electric range of IEC 60309 plugs and sockets.

Despite being a Trademark, it has effectively become the norm for referring to an IEC 60309 plug or socket. 

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10 hours ago, clive said:

Colin, that plug is a liability. Looks to be a cheap and nasty plug, clamped on the conductors not the outer sheath and so on. The live conductor looks like it may have suffered damage? Or maybe a loose screw terminal?

Probably a 99p fantastic from the local hardware outlet, but then good quality plugs are hard to find these days.

The live (brown) wire was perfect a few days ago when the fuse was replaced (it wasn't the fuse but the pressure switch that ended up being replaced) so this overheating has happened in the course of one afternoon's blasting work.

I have one dedicated heavy circuit in the garage, for the lift, so may have to splice into that for the compressor which is, as it always happens, at the other end of the garage. The rest are just standard sockets.

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Agreed quality plug tops are rarer, guess as everything comes with an attached plug now. But do you have screwfix/toolstation etc near you? they sell some quality stuff (as well as cheap tat) 

I would expect the brown wire had some internal damage to some of the strands creating a hotspot. Or as above, screw terminal had got a little loose. (I keep seeing that on electric shower connections, the conductor must compress over time as teh terminals are often loose, then you get burn marks, eventually failure from overheating. Not good )

If you run the compressor off a commando plug (good idea) I would want it "fused" to 16A in the supply/consumer unit as those plugs are not fused. You don't want a fault and the compressor cable catching fire.... or worse.

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1 hour ago, clive said:

I would expect the brown wire had some internal damage to some of the strands creating a hotspot. Or as above, screw terminal had got a little loose. (I keep seeing that on electric shower connections, the conductor must compress over time as teh terminals are often loose, then you get burn marks, eventually failure from overheating. Not good )

If you run the compressor off a commando plug (good idea) I would want it "fused" to 16A in the supply/consumer unit as those plugs are not fused. You don't want a fault and the compressor cable catching fire.... or worse.

Lol funny you should mention showers.... my ceiling pull-switch melted back in August; the electrician who had wired it four months previously came back again and blamed a cheap switch - which I had supplied, from Screwfix. I bought a heavy duty version locally and have had no problems since. The old one had a very heavy 'clunk' when pulled, the new one is very smooth.

I'll be in touch with the electrician who wired the new garage when it was built and see what options I have for stringing a heavier cable to the compressor. The strain that constant running for sandblasting puts on it is obviously becoming too much.

 

 

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May be a bit of a red herring blaming the plug, let alone the way you wired it (conductors crossedbover & compressed)

As said above, may be better to.'hard wire' a compressor via a panel like that for an electric cooker.    Idid this after the 13 A fuse in my three pin plug repeatedly blew.   A powerful electric motor that staryscslowly drawsca lot more current then than it does at speed.    This was blowing the fuses.    Now, as I have a breaker (&residual current) protected ring main in the garage, relies on that for protection, of both me and the wiring - and it never blows!

John

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21 hours ago, Spitfire6 said:

Hi thescrapman,

What industry are you from? Never heard anyone say the word Commando plug when talking about BS60309/BS4343 plugs. First time.

Cheers,

Iain.

I work in the Electricity distribution industry, but that is slightly misleading as I do IT support so the nearest I get to the big voltages is listenning to the transformers humming or (if running at over 100% capacity) rattling in the substations.

We do plug our UPS into commando sockets under the floor or on the suspended ceilings.

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15 hours ago, JohnD said:

May be a bit of a red herring blaming the plug, let alone the way you wired it (conductors crossedbover & compressed)

As said above, may be better to.'hard wire' a compressor via a panel like that for an electric cooker.    Idid this after the 13 A fuse in my three pin plug repeatedly blew.   A powerful electric motor that staryscslowly drawsca lot more current then than it does at speed.    This was blowing the fuses.    Now, as I have a breaker (&residual current) protected ring main in the garage, relies on that for protection, of both me and the wiring - and it never blows!

John

John, I hope the circuit you have the compressor on has a 16A breaker...

And trust me, cheap plugs, damaged cables, loose connections are all likely to cause issues. 

Remember a fuse/breaker is there to protect the cables (not the appliance).So the "fuse" must have a lower rating than any cable in that circuit. Your compressor cable rating is likely to be 16A.  Likewise for a compressor you want to be using a C type breaker.

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  • 1 year later...

Just to resurrect this topic after - yikes 22 months....!! The symptoms were still going on, lots of blown fuses and driving me up the walls, as if the motor was fighting against itself. No amount of ventilation or oil changes would help.

A chance visit to another TSSC member yesterday led to me inspecting his very similar but much newer compressor, and he reckoned that if mine was cutting off at the thermal cutout, with no hiss of escaping air through the exhaust pipeline, then when the compressor was restarting it was fighting against a piston full of air before it could start off. Once home I removed and cleaned the pipe, new olives on each end and replaced but no difference. HOWEVER it was the lack of the hiss of air that gave me the clue, now that I understood what it meant - a quick check of the air release valve soon revealed that the spring was twisted sideways and would work only under very extreme force, or if manually triggered.

Removed, cleaned, oiled and replaced, and adjusted to a few psi lower, we're working very well so far. I may replace it due to a suspicion that it's a cheap copy from some far off factory - I replaced the original which I still have, in a vain attempt to cure the problem years ago and may reuse it in case it's better quality.

Reading back through the entire thread there were a lot of close clues and very good tips, but it just took that understanding of how it works to finally click. 

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