Immersion fuse or MCB?

[mainline]

This reminds me of the threads John-SJW used to create. Where he just kept enticing people to reply to them even though he was just spouting the same (and often wrong) stuff the whole time.

I think it must class as entertainment?

Entertainment as in court jester

 

[davesparks]

A double pole MCB could be used in a small local enclosure isolating and protecting an appliance. Far better, but it is not one-shot and instantly re-settable.

How is it far better?

 

[Steve-S]

Double pole mcb in its own enclosure jezzzzz

Yes. Few know you can have a 16A load off a final ring. Needs to be fixed wiring, overcurrent protection and a switch. A double pole MCB covers it all off the ring and being the isolator for the 16A appliance.

But a 13A MCB can be used as well for 13A appliances instead of an FCU. Which gives superior dp protection.

 

[davesparks]

If a cable is constantly warm the insulation will deteriorate far quicker than always staying cool.

Standard cables used in the UK are designed to operate with a conductor temperature of 70 degrees C.
Current ratings given in the regulations are based on that conductor operating temperature and have tolerance already built in to them to ensure this is not exceeded when installed in accordance with the regulations.

 

[Steve-S]

How is it far better?

As James wrote: "In general an mcb (of the right trip characteristics) is better for most applications". dp even better.

 

[davesparks]

Yes. Few know you can have a 16A load off a final ring.

Can you support that with evidence?
This was certainly true under previous versions of the regulations but as far as I can remember it has not been permitted for a number of years.

. Wich gives superior dp protection.

DP protection is not needed in standard UK domestic wiring fed from the public supply. It is not in any way superior in that situation.

 

[davesparks]

As James wrote: "In general an mcb (of the right trip characteristics) is better for most applications". dp even better.

I'll ask again, how is it better?

How is DP better?

 

[Steve-S]

So now fuses are better if they're provided with sufficient air circulation? You had the answer all along

Nope.

 

[Steve-S]

How is it far better?

You need to ask that?

 

[James]

Yes. Few know you can have a 16A load off a final ring. Needs to be fixed wiring, overcurrent protection and a switch. A double pole MCB covers it all off the ring and being the isolator for the 16A appliance.

But a 13A MCB can be used as well for 13A appliances instead of an FCU. Which gives superior dp protection.

I would have to check that but thought that if not prohibited it is certainly discouraged.

I don't understand why you are pushing a solution to a problem that rarely exists and more often than not, a better solution is available.

 

[DPG]

You need to ask that?

Just answer the question. You seem to struggle with that.

 

[James]

I'll ask again, how is it better?

How is DP better?

I prefer an mcb in MOST applications as you have a better control over the trip characteristics.

please don't take that as one is better than the other, they both have there uses and should be chosen correctly depending on that.

 

[davesparks]

I prefer an mcb in MOST applications as you have a better control over the trip characteristics.

please don't take that as one is better than the other, they both have there uses and should be chosen correctly depending on that.

I know you know the answers, I'm trying to get the OPs answer to try to understand what their point is

 

[davesparks]

You need to ask that?

Yes because I don't see any reason, for the type of circuit being discussed here,why DP protection is any better than SP protection.

I am trying to understand your point but cannot do that without you actually explaining it in a way that makes sense. If you cannot offer a clear, technical explanation of your side of the discussion then there's no point having the discussion.

 

[mainline]

Can you support that with evidence?
This was certainly true under previous versions of the regulations but as far as I can remember it has not been permitted for a number of years.

It's likely a 16A MCB fed from a ring could still comply with all of BS 7671's requirements.

DP protection is not needed in standard UK domestic wiring fed from the public supply. It is not in any way superior in that situation.

DP is superior in many ways as it gives safe isolation, guards against polarity reversal and also isolates neutral to earth faults.