Gym treadmill likely load

[littlespark]

Got an issue with gym equipment. ( I keep telling my wife I’m going to the gym, but she doesn’t believe me!)
The gym owner says the circuit for treadmills trips out every now and again.
I went there last week to find a 16A type C RCBO supplying 1x metal clad double 13A socket.
From here, there was 2 plugs.. each plug run in flex to another 13A double socket fixed to the floor.
One double ran 2 x treadmills… the other ran another treadmill and a stairclimber machine.

The stairclimber comes with what looks like a laptop power supply on an EIC lead.. so I don’t think that’s the problem.

I took out the flex, and extended the radial circuit to the 2 doubles… Just seemed a bit DIY to me.


Trying to find specs on the machines, and it suggests each one is a 9A load… which is going to mean another circuit.
I would assume some diversity as there is little chance all 4 machines will be running full speed at the same time.


The circuit tests ok, and the RCBO ramped at 23mA…. But I’m more inclined to think it’s overcurrent rather than earth fault.


One machine seemed to labour a little as the incline was adjusted… I did recommend he get them serviced.

 

[James]

keep out of the gym, i am convinced it does more harm than good!!

 

[littlespark]

keep out of the gym, i am convinced it does more harm than good!!

I’m getting paid for it though.

He was all ready to offer me free membership after I got his door entry system working properly.

 

[James]

Ha, ha, take the money and pass on the membership!

 

[Lucien Nunes]

Yes 9A is realistic as a peak load, because the motors are rated up to 2hp. They are not likely to run at this power for any length of time. They are usually DC motors fed from some kind of speed controller typically PWM from rectified mains. If they don't have active pfc, the power factor might be quite low over much of the output power range.

 

[littlespark]

Yes 9A is realistic as a peak load, because the motors are rated up to 2hp. They are not likely to run at this power for any length of time. They are usually DC motors fed from some kind of speed controller typically PWM from rectified mains. If they don't have active pfc, the power factor might be quite low over much of the output power range.

When I looked up the model no. (95T) I get details of 4hp up to 8…. Couldn’t be right for something on a 13A plug.

I don’t think upgrading the OCPD to 20A will make a lot of difference. I might have to suggest a second circuit.

 

[mainline]

When I looked up the model no. (95T) I get details of 4hp up to 8…. Couldn’t be right for something on a 13A plug.

I don’t think upgrading the OCPD to 20A will make a lot of difference. I might have to suggest a second circuit.

Maybe worth putting a clamp meter on the individual machines to check current and leakage.

 

[mainline]

I’m getting paid for it though.

He was all ready to offer me free membership after I got his door entry system working properly.

The only time I would take up a free membership to a gym is if they had a café

 

[littlespark]

The only time I would take up a free membership to a gym is if they had a café

No such luck.

There’s a vending machine full of energy drinks.

Could do with parking a burger van right outside.

 

[Taylortwocities]

Although its a C curve RCBO, I'll bet it is start up surge that is tripping it. As far as I read it, you have three treadmills and a stairclimber running from one 16A RCBO?
Probably when one or two machines are running, then the start-up surge for another will trip it.

Run a nice, new 4mm 32A radial.

 

[littlespark]

Exactly right, Taylor

I didn’t have the specs of the machine last week, but thought a proper radial would be better than the glorified extension leads they were using.

Still don’t have the exact specs, but overload was my first thought.

I’ll try and clamp one of the machines today.

 

[Taylortwocities]

Exactly right, Taylor

I didn’t have the specs of the machine last week, but thought a proper radial would be better than the glorified extension leads they were using.

Still don’t have the exact specs, but overload was my first thought.

I’ll try and clamp one of the machines today.

Yes, but the clamp probably wont tell you the surge, only the running current.

 

[mainline]

Yes, but the clamp probably wont tell you the surge, only the running current.

That would depend on what clamp meter you have, some can show the inrush.
Even so, it may show a deviation between machines that are the same and will obviously show the total load, which may help.

The other thing that we are not aware of is has this only started tripping recently or has is it only happening since another machine's been added etc.

It pretty much seems to be a case for a decent supply though.

 

[littlespark]

Even the running current, if high enough… knowing a momentary surge would take it past the 16A for long enough…. Or if 3 out of 4 machines running would be too much anyway.

One of them made a different noise when the incline was adjusted… so it may be straining the motor.
I did suggest to unplug this particular machine, see if it helps until I can be there to test them properly.