So much for consulting the rating plate !

[SimonH2]

Testing/inspecting the appliances in the house I've just bought, all went well until the last item - a microwave in the kitchen. Turn it round to get the details from the rating plate, and this is what I found

Untitled

• SimonH2
• 21 Mar 2011
• 1

The mind boggles at how they came up with quite so many ratings.

I figure it's 850W or 900W (230V or 240V) as a microwave, 1300W or 1500W as a grill, and 2800W max overall. Except that 900+1500 came to 2400 when I was at school - so dunno where the 2800 comes from.


But at least I had one proper fault to fix - I reckon a 170W freezer shouldn't have a 13A fuse in it's plug, although it's cable does look like it's sized for it.

 

[skenk]

1500w microwave, 1300w as a grill, 2800 max, 850w/900w refers to the output power it would appear

 

[STI]

Agree with skenk.

Also on the freezer most come fitted with a 13a as per the manufacturers specs. Start up currents, defrost cucles etc, Same with fridges and most TVs on paper dont need a 10A fuse for an 85watt power consumption but thats what you get.

 

[ajrobb]

Some people go to town on freezer supplies; SWA cable to socket and no RCD. A 'protective' device tripping can cost £100s in damaged food or poisoning. If the cable is 1.5mm², wouldn't that be right for a 13 A fuse?

 

[SgtTrojan]

So the million dollar question is:

What is the design current?

 

[ericmark]

I was taught the fuse in the plug protects the cable. All appliances must be designed for whole of Europe and any fuse to protect the appliance under 16A should be fitted in the appliance not the plug.

Where an appliance is designed not to be portable as with built in stuff this does not apply and a gas hob or bathroom fan for example can stipulate that a 3A fuse is fitted.

The 3A fuse in the plug is purely to allow items like bedside lamps, TV, etc. to have a power cable under 1.25 mm sq. There are two preferred fuse sizes 3A and 13A. So 0.75 mm sq cable has a 3A fuse. Table 52.3 shows 0.75 as smallest permitted but table 4F3A starts at 0.5 mm sq rated 3 A.

0.75 mm sq is rated 6A so could use a 5A fuse and 1 mm sq rated at 10A.

Having said that I have whole range 1, 2, 3, 5, 7, 10, and 13 amp and most standard lamps do have 1A fitted in my house. However when PAT testing I had just 3, 10 and 13 the latter seemed to build up as removed from items. The 10 A is not a preferred size but since there are items wired in 1 mm sq cable I question that?

But early in my apprenticeship I realised that reading the rating plate with items with motors and transformers was not a good idea when selecting a fuse. Today modern switch mode can also cause a problem and so better not to try and fuse to min but to fuse according to feed cable.

 

[SimonH2]

I was taught the fuse in the plug protects the cable. All appliances must be designed for whole of Europe and any fuse to protect the appliance under 16A should be fitted in the appliance not the plug.

Sounds about right.

Where an appliance is designed not to be portable as with built in stuff this does not apply and a gas hob or bathroom fan for example can stipulate that a 3A fuse is fitted.

And then the plumber or kitchen fitter can wire it directly to the CCU with only a 32A breaker protecting it

 

[ericmark]

I was taught the fuse in the plug protects the cable. All appliances must be designed for whole of Europe and any fuse to protect the appliance under 16A should be fitted in the appliance not the plug.

Sounds about right.

Where an appliance is designed not to be portable as with built in stuff this does not apply and a gas hob or bathroom fan for example can stipulate that a 3A fuse is fitted.

And then the plumber or kitchen fitter can wire it directly to the CCU with only a 32A breaker protecting it

Anybody can work on electrics but in a kitchen to do it legal then either you need to be qualified to be able to join a scheme or have everything checked by the LABC. We can't stop illegal work but that is down to the owner of the house. No completion certificate no pay.

The problem that an oven, hob, or any other built in appliance can be plugged in is also covered. In a kitchen any "Fixed" wiring must be notified so simply nailing some cable cleats in to tidy up an extension lead needs notifying under Part P. Since the oven is fixed even if plugged in still needs notifying so the only item which could have wrong fuse is fan in loo or utility room. For some reason Utility room and loo although they have water are deemed not special locations but any food preparation areas are.

Don't ask me why. Ask labour government who put in Part P.

 

[SimonH2]

The problem that an oven, hob, or any other built in appliance can be plugged in is also covered. In a kitchen any "Fixed" wiring must be notified so simply nailing some cable cleats in to tidy up an extension lead needs notifying under Part P. Since the oven is fixed even if plugged in still needs notifying so the only item which could have wrong fuse is fan in loo or utility room.

In this case, almost certainly done pre-Part-P.

I also noticed when I pulled the oven for a look that the sticker on the top says to use rigid piping and use of a flexible hose will invalidate the warranty - so it's connected with a flexible hose which actually makes sense as it would be physically impractical to do it in rigid pipe.

 

[1john]

The problem that an oven, hob, or any other built in appliance can be plugged in is also covered. In a kitchen any "Fixed" wiring must be notified so simply nailing some cable cleats in to tidy up an extension lead needs notifying under Part P. Since the oven is fixed even if plugged in still needs notifying so the only item which could have wrong fuse is fan in loo or utility room.

In this case, almost certainly done pre-Part-P.

I also noticed when I pulled the oven for a look that the sticker on the top says to use rigid piping and use of a flexible hose will invalidate the warranty - so it's connected with a flexible hose which actually makes sense as it would be physically impractical to do it in rigid pipe.

I think that refers to a gas supply.

 

[SimonH2]

The problem that an oven, hob, or any other built in appliance can be plugged in is also covered. In a kitchen any "Fixed" wiring must be notified so simply nailing some cable cleats in to tidy up an extension lead needs notifying under Part P. Since the oven is fixed even if plugged in still needs notifying so the only item which could have wrong fuse is fan in loo or utility room.

In this case, almost certainly done pre-Part-P.

And I've just checked, it's not notifiable as it doesn't involve any fixed wiring. I don't believe the flex from the CCU to the appliance is defined as fixed wiring.

Schedule 4 (non-notifiable work) says :
1. Work consisting of—
(a) replacing any fixed electrical equipment which does not include the provision of—
(i) any new fixed cabling, or
(ii) a consumer unit;

and Part P itself says in general guidance :
The fitting and replacement of cookers and electric showers is not notifiable unless a new circuit is required.

I think that refers to a gas supply.

Perhaps I should have mentioned that it's a gas oven