Compressor Tripping Circuit Breaker

[JonnyAlpha]

Hi,

I fitted a new 20Amp Pressure Switch to my Burisch 3HP Compressor and have also had some new sockets fitted in my garage.
The original sockets that powered the Compressor are a fused spur on the ring main in the house.
This is the first time this compressor has been connected to the new sockets and as soon as I switched it on it tripped the breaker.
I then plugged it into an extension lead that I have used before and plugged that into a socket in my workshop - same problem.

The sockets in the garage are fed from a 16Amp Breaker, this is fed from a 16Amp breaker in the workshop which is fed from a 32Amp Breaker in the Consumer Unit in the house.
I was told by the electrician that 16Amp breaker can be swapped for a 20Amp Breaker.
Could it be that the compressor is drawing to much power at startup and causing the breaker to trip? Should I get the 16Amp swapped out with a 20Amp.

Here’s a pic of the breakers.

Tks

 

[Al Strachan]

Could it be that the compressor is drawing to much power at startup and causing the breaker to trip? Should I get the 16Amp swapped out with a 20Amp.

most likely the problem. Standard practice for motors/inductive loads is to fit a type C or D breaker which allows for motor starting.

20A might be fine, but depends if you have seperate motor overload protection and the wiring is suitable, so on the other side of a computer I'd say fit a type C or even D breaker.

 

[JonnyAlpha]

most likely the problem. Standard practice for motors/inductive loads is to fit a type C or D breaker which allows for motor starting.

20A might be fine, but depends if you have seperate motor overload protection and the wiring is suitable, so on the other side of a computer I'd say fit a type C or even D breaker.

So in the Consumer unit in the workshop, change the B16 for a C or D20 and change the B16 in the workshop (where the compressor is) change the B16 for a C or D16.

 

[JonnyAlpha]

I’m guessing I should try and stick to the same brand CPN. Think I can get them locally.

 

[Al Strachan]

just re-reading your original post. might be best if do a small sketch of your supplies.

The way i understand it, you are supplying a 16a breaker, from a 16a breaker, then from a 32 breaker? Whats the cable CSA's on all circuits (and approx lengths)?

a 16a type C for your compressor yes, but the circuit behind it should be man enough to not need motor rated breakers. and have a breaker suitable for the circuit.

 

[WorkshopChris]

So in the Consumer unit in the workshop, change the B16 for a C or D20 and change the B16 in the workshop (where the compressor is) change the B16 for a C or D16.

I would be thinking hard before recommending a D rating without giving some serious consideration to the earthing arrangements, cable type and existing installation methods.

 

[brightspark]

most likely the problem. Standard practice for motors/inductive loads is to fit a type C or D breaker which allows for motor starting.

20A might be fine, but depends if you have seperate motor overload protection and the wiring is suitable, so on the other side of a computer I'd say fit a type C or even D breaker.

don't be fitting a d type go for a c type 20amp 3hp motors run at about 12 full load amps but the starting load will be about 50 momentarily

 

[JonnyAlpha]

just re-reading your original post. might be best if do a small sketch of your supplies.

The way i understand it, you are supplying a 16a breaker, from a 16a breaker, then from a 32 breaker? Whats the cable CSA's on all circuits (and approx lengths)?

a 16a type C for your compressor yes, but the circuit behind it should be man enough to not need motor rated breakers. and have a breaker suitable for the circuit.

CSAs?

I’ll draw up a sketch later.

 

[brightspark]

csa cross sectional aeria of cable. if its 2.5mm and not a mile long it will carry 28 amps depending how installed

 

[JonnyAlpha]

CSAs?

I’ll draw up a sketch later.

csa cross sectional aeria of cable. if its 2.5mm and not a mile long it will carry 28 amps depending how installed

Doh!
It’s 30metres SWA from house CU to Wksp CU then 16A MCB to Garage CU via SWA (can’t remember the CSA of either of the SWA runs) then in the Wksp CU 16A MCB 2.5mm radial - about 5m run to Compressor socket.
Just plugged the compressor into the old garage fused spur to rule out the new pressure switch being a problem and it worked ok. Fused spur is off a 32A protected ring main.

 

[JonnyAlpha]

just re-reading your original post. might be best if do a small sketch of your supplies.

The way i understand it, you are supplying a 16a breaker, from a 16a breaker, then from a 32 breaker? Whats the cable CSA's on all circuits (and approx lengths)?

a 16a type C for your compressor yes, but the circuit behind it should be man enough to not need motor rated breakers. and have a breaker suitable for the circuit.

Doh!
It’s 30metres SWA from house CU to Wksp CU then 16A MCB to Garage CU via SWA (can’t remember the CSA of either of the SWA runs) then in the Wksp CU 16A MCB 2.5mm radial - about 5m run to Compressor socket.
Just plugged the compressor into the old garage fused spur to rule out the new pressure switch being a problem and it worked ok. Fused spur is off a 32A protected ring main.

 

[Al Strachan]

if your sparky says he can fit a 20, then go for it, but sound like a lot hanging off a 2.5mm back to your workshop. lights and a few other bits and pieces and you'll be tripping the 20a before the 16a type C in the garage (if i understand correctly). You don't really have much room for proper separation, but as long as each circuit is sufficiently protected it will be safe enough.

Apologies for type D faux pas folks

 

[JonnyAlpha]

if your sparky says he can fit a 20, then go for it, but sound like a lot hanging off a 2.5mm back to your workshop. lights and a few other bits and pieces and you'll be tripping the 20a before the 16a type C in the garage (if i understand correctly). You don't really have much room for proper separation, but as long as each circuit is sufficiently protected it will be safe enough.

Apologies for type D faux pas folks

Heres the rough sketch:

 

[Al Strachan]

I’m sure others might have some better ideas, but I’d be looking right back at the house, what cable goes out there and what the biggest breaker can be fitted, then maybe upgrading the 4m run to get a 32a or bigger than 20a breaker to the garage.

I think you’ll always get nuisance trips with a 16a type c and 20a supply, but possibly
Worth a try