Switch fuse for tails

[ringer]

New position of replacement Consumer Unit for my customer is now going to be 7m away from the supply head. DNO fuse is 100A BS1361 and this is a large house so I still need a (potential) 100A supply. I believe that I am supposed to fit a switch fuse if tails are over 3m long. Firstly, am unclear if this is a regulation or just an undocumented 'DNO requirement'. Secondly, can anyone recommend a make and model of switchfuse suitable for use in a domestic environment? Am concerned about aesthetics (it might have to be on show) and cost - I see some commercial/industrial ones cost £100s. Presumably the enclosure would have to be of metal construction, though that is not clear either. Which ones have you fitted and what is your opinion of them? One other point - if I fit a 100A switchfuse, how will that discriminate (select?) before the DNO supply head fuse?

 

[MDJ]

New position of replacement Consumer Unit for my customer is now going to be 7m away from the supply head. DNO fuse is 100A BS1361 and this is a large house so I still need a (potential) 100A supply. I believe that I am supposed to fit a switch fuse if tails are over 3m long. Firstly, am unclear if this is a regulation or just an undocumented 'DNO requirement'. Secondly, can anyone recommend a make and model of switchfuse suitable for use in a domestic environment? Am concerned about aesthetics (it might have to be on show) and cost - I see some commercial/industrial ones cost £100s. Presumably the enclosure would have to be of metal construction, though that is not clear either. Which ones have you fitted and what is your opinion of them? One other point - if I fit a 100A switchfuse, how will that discriminate (select?) before the DNO supply head fuse?

I agree a switch fuse is a good idea, I like Schnieder but you will have plenty of choice, speak to your wholesaler mate.

 

[Wilko]

Hi - could try this Wylex one
Wylex 100 Amp SP&N Switchfuses - https://www.tlc-direct.co.uk/Manufacturers/Wylex/Switchfuse_SP_and_N/index.html

 

[ringer]

To MDJ - Oh dear - is this now going to turn into a slanging match? I hope not. A genuine contractor here asking a genuine question about a real-life on-the-job scenario. As a sole-trader it is at times difficult to know exactly what to do for the best in some circumstances, hence my question. If you do not have a sensible answer then please refrain from muddying the waters further with your unhelpful response.

 

[MDJ]

To MDJ - Oh dear - is this now going to turn into a slanging match? I hope not. A genuine contractor here asking a genuine question about a real-life on-the-job scenario. As a sole-trader it is at times difficult to know exactly what to do for the best in some circumstances, hence my question. If you do not have a sensible answer then please refrain from muddying the waters further with your unhelpful response.

Not at all it was a bit of fun, and I gave you a answer afterwards, I thought your question was a good one, you have now had 2 answers, regarding the 2nd one, the wylex unit is also decent, there are dozens of types, I prefer the type where there is room around the busbar, in general these switch fuses are tight and seem to get smaller, not sure about BG which is the cheaper option, at 7 mtrs of tails a switch fuse is a requirement.

 

[ringer]

Thank you for a now helpful response. Someone else suggested Schneider but no model name given. Yes, I can ask my wholesaler but they are only likely to suggest whatever they have in stock. I am looking for recommendations of what others have successfully used. A model number would be useful so I can google it and see what they look like.

 

[MDJ]

Thank you for a now helpful response. Someone else suggested Schneider but no model name given. Yes, I can ask my wholesaler but they are only likely to suggest whatever they have in stock. I am looking for recommendations of what others have successfully used. A model number would be useful so I can google it and see what they look like.

How much room have you got in the area where the switch fuse will be fitted?

 

[SparkyChick]

New position of replacement Consumer Unit for my customer is now going to be 7m away from the supply head. DNO fuse is 100A BS1361 and this is a large house so I still need a (potential) 100A supply. I believe that I am supposed to fit a switch fuse if tails are over 3m long. Firstly, am unclear if this is a regulation or just an undocumented 'DNO requirement'. Secondly, can anyone recommend a make and model of switchfuse suitable for use in a domestic environment? Am concerned about aesthetics (it might have to be on show) and cost - I see some commercial/industrial ones cost £100s. Presumably the enclosure would have to be of metal construction, though that is not clear either. Which ones have you fitted and what is your opinion of them? One other point - if I fit a 100A switchfuse, how will that discriminate (select?) before the DNO supply head fuse?

I've just used a couple of Hamilton HLMFS. Significantly cheaper than the Wylex, seem to be good build quality, 100A maximum, comes with 63A, 80A and 100A fuses. Earth bar easily accommodates 16mm.

Nice units.

I wouldn't worry about discrimination. The switch fuse is there because the DNO won't guarantee their fuse will blow in time in the event of a fault on the tails if they are longer than 3m.

 

[Gavin John Hyde]

I have used the Lewden ones a bit in the past. not too pricey and most wholesalers can get them in, if you want to save money have a look at
Wylex Single Phase Switchfuses - Discount Electrical - http://www.discount-electrical.co.uk/section.php/108706/1/wylex-single-phase-switchfuses
you can get a wylex one for £60 inc of VAT. with free delivery.

 

[ringer]

How much room have you got in the area where the switch fuse will be fitted?

Potentially as much as I want - the room where it will sit is going to be remodelled - currently a kitchen it will end up as a bedroom.

 

[ringer]

Am assuming here it is would be unwise to try and fit it in the meter cupboard outside.

 

[MDJ]

well the more room the better, I have a single phase 100 amp MEM switch fuse if you want it, not sure what the P&P would cost but it is immaculate and never used, probably 7-8 years old and industrial but it is yours if the postage is not a problem. In fact I may be wrong it may be an isolator I will have a look.

 

[MDJ]

 

[MDJ]

Apologies it looks like an Isolator I will go and take a look and PM you if it is a Switch fuse.

 

[SparkyChick]

Am assuming here it is would be unwise to try and fit it in the meter cupboard outside.

I put the Hamilton one in a meter cupboard, no problem.

 

[ringer]

well the more room the better, I have a single phase 100 amp MEM switch fuse if you want it, not sure what the P&P would cost but it is immaculate and never used, probably 7-8 years old and industrial but it is yours if the postage is not a problem. In fact I may be wrong it may be an isolator I will have a look.

Thanks MDJ but they are just too industrial looking. I know I could potentially box it in, but really need something that looks 'ok' if on show in the house. Will probably end up near the ceiling in a bedroom. If it is hidden away I worry they might not realise it is there if the fuse blows - unlikely I know, but still possible.

 

[MDJ]

Thanks MDJ but they are just too industrial looking. I know I could potentially box it in, but really need something that looks 'ok' if on show in the house. Will probably end up near the ceiling in a bedroom. If it is hidden away I worry they might not realise it is there if the fuse blows - unlikely I know, but still possible.

Fair enough, the Wylex looks pretty small, you should get more replies later mate when the guys get home from work.

 

[Midwest]

I put in one of those a Wylex ones Wilko linked, in my own house as it happens. They don’t look half bad. Put in one of Lewden ones, and not a lot of room inside as I recall?

Just enough earth terminals in the Wylex one, also if I recall?

I’ve read here that some DNO/Suppliers get arsy with you putting stuff in ‘their’ meter cabinet, and the Wylex one is quite big, something to bear in mind.

 

[multimick]

where you buy the hamilton from SC ?

 

[SparkyChick]

where you buy the hamilton from SC ?

Local independent wholesaler. Went it trying to get hold of the Wylex at a price better than Screwfix and came out paying around half the price of the Wylex.

 

[SparkyChick]

I’ve read here that some DNO/Suppliers get arsy with you putting stuff in ‘their’ meter cabinet, and the Wylex one is quite big, something to bear in mind.

Where it went in a Western Power cupboard, they supplied the cupboard complete with the back board and there is space allocated on their back board if I recall for just such a purpose.

I suspect if it fell outside the allocation they might get the hump, but the Hamilton one fits nicely in the space they give you. SWA gland at the bottom was a bit tight, but other than that it was alright.

 

[Dobes_88]

Have only installed the Wylex types but would recommend them, plenty of room inside and look smart. You'll need to have an allen key set handy if you go for them as they've done away with the normal PZ/SL terminals.

 

[mattg4321]

Wylex one is far better than Lewden IMO

 

[stevels4]

Have you confirmed the cut out fuse is indeed 100A, fit a KMF and re-tail from there unless you fancy having a fight with 7 metres of 25mm split concentric

 

[coolsparx]

I’ve fitted a few of the Lewden ones (FS6380100) inside meter boxes & not had a problem.