Ovens and heat resistant cable

[stem]

I have had a new kitchen fitted. There are two ovens mounted one above the other. One is a standard single oven and the other is a combination microwave.

In anticipation of this I installed two a separate circuits, one for each oven from its own 16A MCB via a 20A DP switch. The final connection to each oven was a length of 2.5mm heat resistant cable (as used for immersion heaters)

I expected the ovens to have a set of terminals that the flex would simply connect to. When they arrived, they were fitted with moulded 13A plugs attached to a very short length of flex terminated inside the oven like a normal counter top microwave. (The oven instructions refer to this cable as heat resistant also)

My initial thoughts are;

1) Terminating the HR flex at two 13A sockets directly behind the ovens inside the cabinet carcase and plugging the ovens in. (How heat resistant is a 13A socket?) Problem here, is that to access the 13A fuse, the oven must be removed.

2) Cutting the plug off and connecting directly to the HR flex. (Is there a suitably rated heat resistant jbox with cable clamps for this purpose?) This will also loose the protection of the 13A fuse for direct connection to a 16A MCB. Is this OK?

The Building inspector is inspecting the electrical installation later this week, so I need to get it right.

Thanks in anticipation

 

[Adam_151]

You could just plug them in to sockets fitted on the feeds from the switches, I dont think ovens and microwaves blow fuses for no reason, if the fuse blows chances are you'd have to pull them out to fix the appliance anyway...

Or, change the 20A DP switches for FCUs and then while you could hardwire, I'd recommend BS546 15A roundpin plugs and sockets behind the appliances, these are unfused, so the ovens can be easily disconnected for maintainance purposes

 

[JohnD]

I'd go with sockets behind, controlled by your 20A switch. That way they will be easy to take out if they need to be repaired or replaced.

The switch will isolate it if required.

The chance of a fuse blowing is only very slightly above nil, and if it does, there is probably a fault that means the oven will have to be taken out for repair or chucked in the skip (edited: As Adam says).

I wouldn't bother going for round-pin sockets and plugs when you already have a perfectly serviceable plug supplied.

If you are using 13A fused plugs, then don't use FCUs. That would mean you would have two fuses for the same appliance. No point, and it doubles your fault-find-and-fix effort if one or both blows.

 

[Diyisfun]

Stem said

Terminating the HR flex at two 13A sockets directly behind the ovens inside the cabinet carcase and plugging the ovens in. (How heat resistant is a 13A socket?) Problem here, is that to access the 13A fuse, the oven must be removed.

Couldyou not fit the 13amp sockets in the cupboard as against behind the ovens. As has been said the chances of the fuse blowing is slight, but its about having to remove the oven to check.

 

[JohnD]

p.s. As you have a 15A MCB you do not really need a 13A fuse at all, either in an FCU or a plug.

It's just that the plug is so much more common and familiar, and will be supplied with the next microwave you buy, so in my view it's convenient to keep it.

But if you don't use a 13A plug, there's no need to fit a FCU with a 13A fuse.

I am sure your BCO would have no objection to any of the methods described, they are all safe.

 

[Adam_151]

Interesting read here John, http://www.theiet.org/forums/forum/...did=8812&highlight_key=y&keyword1=overvoltage

In reality there is going to be no difference between whether the 13A fuse is there or not, but is this a case that if you want to do things properly then you should keep it? It seems somewhat absurd to me, but oh well...

Just something to think about

 

[JohnD]

Thanks, Adam!

Can't see any reason for keeping it, except the convenience of having a plug already fitted, though.

 

[stem]

Thanks everyone. I was hoping for a quick response due to pending inspection. Some good logic with all of those comments.

I'll go with the sockets at the back based on if the 13A fuse blows then there will be a good reason for it and it's easier to remove a plugged in appliance if it needs service or repair.