Can an appliance rely on the circuit OPD for O/L protection?

[LoveRocket]

Following on from this thread, I have heard it said that manufacturers CANNOT rely on the circuit OPD to protect their appliance from overload - ie the plugtop fuse on a toaster of the MCB in the CU for a cooker CANNOT be used as part of the manufacturer's design for overload protection.

Put simply, the MCB is there to protect the supply cable, the plugtop fuse is to protect the flex; if an appliance needs overload protection, it MUST be incorporated internally.

(I hope that makes sense)

Is this correct, or just site-talk *******s?[/url]

 

[holmslaw]

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[Taylortwocities]

I have heard it said that manufacturers CANNOT rely on the circuit OPD to protect their appliance from overload

Of course it can.

I am about to provide a 20A radial for a local hotel.It will power a Moderna Expresso Machine. Power loading 3.9KW.

20A MCB in Square D KQ Loadmaster board. 2.5mm cable to DP switched isolator.

That's it.

Appliance protected by CPD in the DB.

 

[LoveRocket]

I have heard it said that manufacturers CANNOT rely on the circuit OPD to protect their appliance from overload

Of course it can.

I am about to provide a 20A radial for a local hotel.It will power a Moderna Expresso Machine. Power loading 3.9KW.

20A MCB in Square D KQ Loadmaster board. 2.5mm cable to DP switched isolator.

That's it.

Appliance protected by CPD in the DB.

Do the MI state that? Are they saying that the supply must be fused at 20a?

Could you supply that machine on a 63a radial? What do the MI actually say?

 

[Taylortwocities]

View media item 23771

 

[ericmark]

Following on from this thread, I have heard it said that manufacturers CANNOT rely on the circuit OPD to protect their appliance from overload - ie the plugtop fuse on a toaster of the MCB in the CU for a cooker CANNOT be used as part of the manufacturer's design for overload protection.

Put simply, the MCB is there to protect the supply cable, the plugtop fuse is to protect the flex; if an appliance needs overload protection, it MUST be incorporated internally.

(I hope that makes sense)

Is this correct, or just site-talk b*****s?

For a 13A plug supplied non built in appliance yes the manufacture should not rely on fuse in plug or MCB on ring main.

However when built in i.e. not fitted with 13A plug then he can specify what external protection is required. A induction hob manufacture could specify a supply protected by a 20A Semi-conductor fuse and if you wanted to keep warranty valid you would need to fit them.

Although not seen Semi-conductor fuses specified I have seen supply size specified at 32A and supply with 45A and splitting at cooker outlet for oven as well is not permitted. If you did then you would be libel for any damage which if it resulted in death could mean a manslaughter charge.

As to if the courts would uphold that no one knows as far as I know there as not been a case brought. However no amount on insurance will cover one for that and so it is important to read instructions.