Which fuse rating to use in a plug

[JohnW2]

You not like the words, but ease of maintenance, and improved reliability of supply.

'Ease of maintenance' can be addressed by some means of isolation. As for reliability ....

If your lights, plugs or what ever, trip on a fault, and cannot be reset due to the fault, your heating system will continue to function.

I wouldn't have that problem in my house. The heating system is usually fed from one of the sockets circuits, but it is supplied by a plug/socket, so that it can be plugged into my genny supply should the need arise (only 'in anger' 2 or 3 times in 40+ years!) - so, if just the one sockets circuit was lost, I could plug it into a different circuit, using an extension lead if necessary (but probably not necessary, since there are sockets on two different circuits close to where the heating plugs in.

If work needs to be done on your boiler circuit, then that can likewise be completely isolated, leaving your plugs/lights etc., all in working order.

As above, that merely needs 'a means of isolation' - in my case just a matter of 'pulling the oplug (and one can't get better isolation than that!)

 

[flameport]

As a a matter of interest, why do you feel that a gas heating system would "be far better off" with a dedicated circuit?

The same reasons that any other devices have their own circuit.
Attaching it to a circuit intended for socket outlets is neither desirable or necessary.

 

[JohnW2]

The same reasons that any other devices have their own circuit. .... Attaching it to a circuit intended for socket outlets is neither desirable or necessary.

With respect, "neither desirable or necessary" is hardly explicit enough to be a useful answer to my question.

Are you suggesting that every single bit of electrical/electronic equipment which does not need 'to be moved around' (which would obviously require connection by plug/socket) should have its own dedicated circuit?

What do you regard as 'undesirable' about the supply to my heating system I described in my last post?

 

[Harry Bloomfield]

I wouldn't have that problem in my house. The heating system is usually fed from one of the sockets circuits, but it is supplied by a plug/socket, so that it can be plugged into my genny supply should the need arise (only 'in anger' 2 or 3 times in 40+ years!) - so, if just the one sockets circuit was lost, I could plug it into a different circuit, using an extension lead if necessary (but probably not necessary, since there are sockets on two different circuits close to where the heating plugs in.

Then, why not take it to the extreme, of doing away with your CU completely? You can scatter your means of isolation, and circuit breakers around the house.

Me, I like things centralised, I go to one CU, of two, which are very well-marked, and I can isolate what-ever circuit I might need to isolate.

 

[Deleted member 142255]

Then, why not take it to the extreme, of doing away with your CU completely? You can scatter your means of isolation, and circuit breakers around the house.

Me, I like things centralised, I go to one CU, of two, which are very well-marked, and I can isolate what-ever circuit I might need to isolate.

He does like to bang on doesn't he lol.

 

[JohnW2]

Then, why not take it to the extreme, of doing away with your CU completely? You can scatter your means of isolation, and circuit breakers around the house.

That's a bit silly for most things - to where would I 'scatter my means of isolation' for things like sockets and lighting circuits?

Having said that, for things like boilers, there is clearly some merit in having a means of isolation fairly local to (at least,within eyesight of') whatever it is isolating

Me, I like things centralised, I go to one CU, of two, which are very well-marked, and I can isolate what-ever circuit I might need to isolate.

Strictly speaking (per BS7671), I can't do that, unless I switch off an RCD (hence killing several circuits -most of my CUs are 'dual-RCD' ones), since I have a TT installation and SP MCBs. If it were TN, I could, and would in most cases, do exactly that - although I would still like a 'means of isolation within eyesight of the boiler' (which my CU wouldn't be).

 

[Harry Bloomfield]

Strictly speaking (per BS7671), I can't do that, unless I switch off an RCD (hence killing several circuits -most of my CUs are 'dual-RCD' ones), since I have a TT installation and SP MCBs. If it were TN, I could, and would in most cases, do exactly that - although I would still like a 'means of isolation within eyesight of the boiler' (which my CU wouldn't be).

My boiler/heating circuit, has a DP isolator, local to it in the kitchen, which only removes power from the boiler. In the airing cupboard, is another DP isolator, which removes power from the boiler, and the entire heating systems controls, under the stairs, is the CU, with a separate MCB just for the heating.

 

[JohnW2]

My boiler/heating circuit, has a DP isolator, local to it in the kitchen, which only removes power from the boiler. In the airing cupboard, is another DP isolator, which removes power from the boiler, and the entire heating systems controls, under the stairs, is the CU, with a separate MCB just for the heating.

Fair enough, but If you have other means of isolating boiler and the rest of the heating system, that does not, in itself, explain why you want it all on a dedicated circuit. I presume the dedicated circuit is because you don't want to lose the heating if some circuit it was fed from was lost - but is that any more likely than a dedicated heating circuit itself being 'lost' (particularly given that 'electricity and water don't mix')?

 

[Harry Bloomfield]

but is that any more likely than a dedicated heating circuit itself being 'lost' (particularly given that 'electricity and water don't mix')?

The likelihood, is of little interest to me, the point is that for little extra cost, circuits can gain independence, and minimise the chances of suffering loss.

 

[JohnW2]

The likelihood, is of little interest to me, the point is that for little extra cost, circuits can gain independence, and minimise the chances of suffering loss.

We have a different attitude to 'risks'. which is fine, and really a matter of "vive la difference" - it would be a boring world if everyone thought the same!

The one thing I would repeat, about my personal way of thinking, is that when it comes to things like alarms and freezers, .I regard the fact that some 'constantly used circuit' (be it lighting, a sockets circuit feeding the TV or whatever) would lose power (as either the 'effect' or the 'cause') when the alarm/freezer/whatever lost power as being a 'positive' thing - but I imagine you feel differently about that.

Kind Regards, John

 

[ericmark]

I have to agree with @JohnW2 I know it says loads over 2 kW to fixed equipment should be on a dedicated circuit, and over 18 kg and not on wheels makes it fixed, but to have a dedicated circuit for the tumble drier, dishwasher, washing machine, and immersion heater, is going OTT.

So we use some common sense, once the house is wired, adding circuits is expensive, the immersion is on a dedicated circuit, but the rest are plugged into one of the ring finals. Yes, I was careful to take the spur for washing machine from a different place as supply for tumble drier, but since drier is heat pump type, now no real need.

The splitting of a 3 kW supply (think 3 kW, not checked) to make separate circuits for the freezers and central heating seems daft. They will never add up to over 3 kW, and having one SWA around the outside of the house is bad enough, without a second one.

I can see the idea of a dedicated outlet,

using a cover, even if only a tie wrap, to stop someone unplugging the boiler would be a good idea, and using a FCU does the same, but can't see reason for a dedicated circuit in real life.

 

[Deleted member 142255]

I can see the idea of a dedicated outlet, View attachment 372405using a cover, even if only a tie wrap, to stop someone unplugging the boiler would be a good idea, and using a FCU does the same, but can't see reason for a dedicated circuit in real life.

It's in the regs. Division of installation.

 

[Deleted member 142255]

Edited

 

[JohnW2]

It's in the regs. Division of installation.

View attachment 372408

Whilst you've been busy elsewhere, over the years 314.2 had been discussed, debated and argued about here 'ad infinitum' on more occasions than I care too recall.

The bottom line is essentially that it is so vague as to be essentially meaningless, since no two people are going to interpret in the same way. It's 314.2(iii) which is usually the bit which has the widest range of interpretations, and readers are only asked to "take account of hazards that may arise from the failure of a single circuit such as a lighting circuit" - and you'd probably be hard-pressed to find two people who assessed "hazards that may arise" in the same way and/or "took them into account" in the same way!

One is really just left with 'common sense', for those who have some.

 

[Deleted member 142255]

Whilst you've been busy elsewhere, over the years 314.2 had been discussed, debated and argued about here 'ad infinitum' on more occasions than I care too recall.

The bottom line is essentially that it is so vague as to be essentially meaningless, since no two people are going to interpret in the same way. It's 314.2(iii) which is usually the bit which has the widest range of interpretations, and readers are only asked to "take account of hazards that may arise from the failure of a single circuit such as a lighting circuit" - and you'd probably be hard-pressed to find two people who assessed "hazards that may arise" in the same way and/or "took them into account" in the same way!

One is really just left with 'common sense', for those who have some.

OMG!

The IET really should pass all this by you before they publish.

Become a spark now while you know it all!