Immersion fuse or MCB?

[DPG]

Now read H5 which makes this thread pointless.

Could you paste it in the thread Westy - in case we haven't got books with us

 

[westward10]

Could you paste it in the thread Westy - in case we haven't got books with us

 

[Steve-S]

The 16A breaker off a ring is mentioned in the OSG in the 17th edition. A double socket is designed to run at 20A which can be off a final ring. So there can be a point off a ring drawing more that 13A. A 16A MCB off a ring draws less.

 

[DPG]

I predict the thread will take another tangent now.

 

[littlespark]

I predict the thread will take another tangent now.

Straight in the bin?

 

[westward10]

The 16A breaker off a ring is mentioned in the OSG in the 17th edition. A double socket is designed to run at 20A which can be off a final ring. So there can be a point off a ring drawing more that 13A. A 16A MCB off a ring draws less.

Where does it say this in the 17th Ed.
You are happy to quote H2.5 from the OSG but ignore H5 which as I said makes this thread of no consequence.

 

[Steve-S]

So immersions over 15ltrs of vessel in capacity have to be on a radial. In 15th.

If one is on a ring with the ring being there for a long while that is fine. Replacing an FCU switch is still fine and replacing the FCU with an MCB is fine as it is just maintenance of existing equipment.

 

[timhoward]

So…..

Did you play the black knight in Monty Python and the holy grail?
Have a beer, stick some music on and think of something else to worry about. The immersion heater won’t work anyway by the time someone wants it to.

 

[mainline]

A 16A MCB off a ring draws less.

The current draw will remain the same whether it's a 13amp fuse or a 16amp mcb.

 

[mainline]

Of course not, but I thought that went without saying. In the average UK installation on the public supply single pole isolation is acceptable and safe.



No, the question was around the OPs statement that DP MCBs offer superior protection to SP MCBs.

Obvious why? In the average UK installation, where the neutral is reliably and solidly connected to earth at source, there is little advantage to DP over SP isolation.
I'd wager that the majority of DP isolators are installed purely due to that being the only kind available rather than any technical requirement to break the neutral.

Any advantage, no matter how small, would make a DP superior to SP.
One advantage would be safe local isolation.
There are other advantages, but I really can't be bothered arguing about the obvious.

 

[Steve-S]

The current draw will remain the same whether it's a 13amp fuse or a 16amp mcb.

No it will not. A double socket is rated to draw 20A (it can draw 26A), yet they are are ubiquitous on rings. That is one point off a final ring. A 16A MCB, one point off a final ring, draws less than a common double socket.

 

[DPG]

No it will not. A double socket is rated to draw 20A (it can draw 26A), yet they are are ubiquitous on rings. That is one point off a final ring. A 16A MCB, one point off a final ring, draws less than a common double socket.

But that's not what you said is it John.

 

[Steve-S]

Any advantage, no matter how small, would make a DP superior to SP.
One advantage would be safe local isolation.
There are other advantages, but I really can't be bothered arguing about the obvious.

On the Continent all breakers in the CU are dp. It is abundantly obvious dp is superior.

 

[mainline]

No it will not. A double socket is rated to draw 20A (it can draw 26A), yet they are are ubiquitous on rings. That is one point off a final ring. A 16A MCB, one point off a final ring, draws less than a common double socket.

If you plug a 3 amp load into a 100 amp circuit, it will draw 3 amps

If you plug the same 3 amp load into a 200 amp circuit, it will draw exactly the same.

 

[mainline]

No it will not. A double socket is rated to draw 20A (it can draw 26A), yet they are are ubiquitous on rings. That is one point off a final ring. A 16A MCB, one point off a final ring, draws less than a common double socket.

The outlet doesn't draw anything, it's the appliance that draws the current.