When to use AFDD’s

[craigbanham]

We currently install industrial washing machines, driers and finishing equipment. These can be three phase and single phase. Normally no greater than 32 amps.

When on a commando socket we will install an AFDD.

If we remove the commando socket and install a standard rotary isolator, do we still need to install the AFDD ?

 

[littlespark]

AFDDs are usually put in at the source, at the fuse board and would cover all circuits.

If AFDDs are specified, then it won’t matter if it’s an isolator, or a plug/socket… it should still be fitted.

Can you give us the make and model number of the AFDD you normally fit?

 

[craigbanham]

AFDDs are usually put in at the source, at the fuse board and would cover all circuits.

If AFDDs are specified, then it won’t matter if it’s an isolator, or a plug/socket… it should still be fitted.

Can you give us the make and model number of the AFDD you normally fit?

Thank you for your reply, we connect to the services provided on site, these range from Wylex, Proteus.

The issue we have is our machines can trip the AFDD’s due to contractors, elements activating.

I understand the requirement in occupied premises but I was under the impression it was on socket outlets only.

 

[littlespark]

Yes. Sorry. You’re spot on.

Extract from OSG below.

However, to me, these property types are for living accommodation.
Industrial machines may be the laundry rooms of these properties, but not where people live.

If the machines are tripping the AFDDs, then maybe they are not required in the first place?

I take it domestic style washing machines don’t cause the same issue?



It’s just strange that an actual fault that AFDDs are designed to detect could go unnoticed just because the appliance has been hard wired instead of plugged in…. Presumably to save the cost of an AFDD by the installer.

 

[craigbanham]

Yes. Sorry. You’re spot on.

Extract from OSG below.

View attachment 118752


However, to me, these property types are for living accommodation.
Industrial machines may be the laundry rooms of these properties, but not where people live.

If the machines are tripping the AFDDs, then maybe they are not required in the first place?

I take it domestic style washing machines don’t cause the same issue?



It’s just strange that an actual fault that AFDDs are designed to detect could go unnoticed just because the appliance has been hard wired instead of plugged in…. Presumably to save the cost of an AFDD by the installer.

This is my point, as the on site guide specifies a socket outlet we install hard wired rotary isolators only. In my opinion no need for the AFDD.

There is no fault with the machine, I think it’s the load that is being switched by the contactor, sometimes this load for heating can be 25 amps plus. The AFDD is doing its job correctly but obviously becoming an issue as the machines can’t be used. I am looking for an opinion and reason for each side of the argument. Which you have kindly provided

 

[littlespark]

The problem is that AFDDs have been a knee-jerk reaction to a tower block fire… supposedly caused by an arc in a kitchen appliance.
They rushed them through to regs without fully investigating these shortfalls.

It was the same with RCDs. They thought an rcd mainswitch would be fine, but no one considered cumulative earth leakage across several circuits.

 

[EalingBadger]

This is my point, as the on site guide specifies a socket outlet we install hard wired rotary isolators only. In my opinion no need for the AFDD.

There is no fault with the machine, I think it’s the load that is being switched by the contactor, sometimes this load for heating can be 25 amps plus. The AFDD is doing its job correctly but obviously becoming an issue as the machines can’t be used. I am looking for an opinion and reason for each side of the argument. Which you have kindly provided

I don't see that it makes a difference whether there is a socket at the end of the circuit or not.

They might be more common on socketed circuits but a loose connection is a loose connection and can appear anywhere.