Graham007 Posted July 20 Share Posted July 20 Hi, I have a boxer 65 can anyone tell me what the mains fuse size is as the original lead has gone missing. Thanks for any help Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 20 Share Posted July 20 There should be an ampere draw rating on the back of the amp near the mains cord plug socket. 1 Quote Link to comment Share on other sites More sharing options...
PaulWarning Posted July 20 Share Posted July 20 3 amp would be safe enough Quote Link to comment Share on other sites More sharing options...
BigRedX Posted July 20 Share Posted July 20 If this is the fuse in the plug of mains lead for the amp it should be rated to protect the lead, not the amp. The amp itself should have a separate fuse. Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted July 20 Share Posted July 20 16 minutes ago, BigRedX said: If this is the fuse in the plug of mains lead for the amp it should be rated to protect the lead, not the amp. The amp itself should have a separate fuse. The same cable and kettle connector is used with an unfused plug in Europe, where the house wiring could be a 20 Amp radial feed. If that is safe in Europe, do we need to worry about 13A/10A/5A/3A fusing for cable protection in the UK? David Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted July 20 Share Posted July 20 (edited) 41 minutes ago, Mottlefeeder said: The same cable and kettle connector is used with an unfused plug in Europe, where the house wiring could be a 20 Amp radial feed. If that is safe in Europe, do we need to worry about 13A/10A/5A/3A fusing for cable protection in the UK? David I wonder how many fires have been started by such cavalier thinking!! What happens in Europe does not comply with the UK's electrical code! Edited July 20 by BassmanPaul 1 Quote Link to comment Share on other sites More sharing options...
tegs07 Posted July 20 Share Posted July 20 1 hour ago, Mottlefeeder said: The same cable and kettle connector is used with an unfused plug in Europe, where the house wiring could be a 20 Amp radial feed. If that is safe in Europe, do we need to worry about 13A/10A/5A/3A fusing for cable protection in the UK? David I’m no wiring expert but the UK has ring mains with multiple outlets and a higher rated CB so the fuse in the plug is important. 2 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted July 20 Share Posted July 20 2 hours ago, Mottlefeeder said: The same cable and kettle connector is used with an unfused plug in Europe, where the house wiring could be a 20 Amp radial feed. If that is safe in Europe, do we need to worry about 13A/10A/5A/3A fusing for cable protection in the UK? David It's not a kettle lead. It doesn't fit any kettle and just as well because your typical amplifier mains cable is not rated sufficiently high enough to take the current draw of a kettle. 1 Quote Link to comment Share on other sites More sharing options...
PaulWarning Posted July 20 Share Posted July 20 (edited) Always amuses me, kettle's don't have kettle leads these days 😀 Am I going to get an apostrophe alert? Edited July 20 by PaulWarning Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted July 20 Share Posted July 20 2 hours ago, tegs07 said: I’m no wiring expert but the UK has ring mains with multiple outlets and a higher rated CB so the fuse in the plug is important. Typically, UK domestic and pub wiring will be a 30A ring main, which is why we have a fuse in the plug. Having said that, if the cable and connector can withstand the forces and heat monentarily generated while blowing a 20A fuse in Europe, does it matter what size of fuse (up to 13A) you fit in the plug in the UK? David Quote Link to comment Share on other sites More sharing options...
tegs07 Posted July 20 Share Posted July 20 56 minutes ago, Mottlefeeder said: Typically, UK domestic and pub wiring will be a 30A ring main, which is why we have a fuse in the plug. Having said that, if the cable and connector can withstand the forces and heat monentarily generated while blowing a 20A fuse in Europe, does it matter what size of fuse (up to 13A) you fit in the plug in the UK? David probably a question for a sparky. Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 20 Share Posted July 20 There are two DIFFERENT fuses for 2 DIFFERENT reasons. I have to deal with this stuff whenever submitting products for international/CB certification testing. The first (in the UK) is the fuse in the "13A" (BS-1363) plug cap, also referred to colloquially as a kettle cord. This fuse is sized based on the wire size in the mains lead wire. This is because of the unique 30A ring circuit in the UK (and some UK colonized locations) where each receptacle is fed from 2 circuits simultaneously configured in a ring type distribution. This is an efficient way (less copper) to deliver power, but inconvenient for protecting because of the higher available fault current. The UK approved fuse style is BS-1362 which has specific opening and clearing characteristics to comply with the regulations. The second is the equipment protection fuse that is used to protect user, the equipment and external wiring from overload and fire in the event of a fault within the equipment. If it's and external fuse that is intended for user replacement, the fuse value must be printed in a specific format on the back of the equipment (the type, voltage and current... like T3A/250V) which says that it's a 5mm x 20mm time delay fuse, 3 amps, suitable for up to 250 volt operation). There may also be an L or H which signifies low or high clearing capacity. If L or H is not present, either L or H rated fuses may be used. The lowest approved plug cap fuse that I have seen is 3A 3 Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted July 20 Share Posted July 20 Thanks @agedhorse. So, from the table, for a 0.75mm^2 conductor (commonly used with moulded on 'kettle connectors' and rated at 6A) you can use a 10A fuse in a rewirable plug and a 13A fuse in a moulded on plug. David 1 Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 21 Share Posted July 21 1 hour ago, Mottlefeeder said: Thanks @agedhorse. So, from the table, for a 0.75mm^2 conductor (commonly used with moulded on 'kettle connectors' and rated at 6A) you can use a 10A fuse in a rewirable plug and a 13A fuse in a moulded on plug. David That's what the regulations say, I am not sure of the date of this data though. .75mm^2 is equivalent to our 19 AWG, and our 18 AWG (slightly larger) cordsets are permitted to be used on 20A branch circuits. This is specifically to prevent fire due to a fault in the cordset, it's not best practice for sizing to a load. In our industry, this is addressed under the safety regulations by providing an equipment located fuse or breaker (called an overcurrent protection device) that is sized in conjunction with the specified IEC cordset size. Since most equipment that we are talking about here is typically protected by a T6.3A or smaller fuse, and will work plenty fine (and safely) with a 75 mm^2 cordset. There are a lot of quirky elements to this topic as you can see. Other countries and regions are even more convoluted. 1 Quote Link to comment Share on other sites More sharing options...
itu Posted July 21 Share Posted July 21 (edited) T = Träge = slow blow F = Flink = fast These are originally German terms. About the diameter of a cable: Usually it is safer to use slightly larger diameteter than that specified, if the cable is in active use. Here active means gigging round the country (and for some of you: the world). As cables will be bent a lot, at some time the copper will be chipped to smaller pieces and the ability to carry the specified current will be less. I have been amazed pretty often that so many bands have invested to equipment, but not to functional cables. When I joined one band long ago, their cables were just a mess in two or three plastic bags. Some cable was always missing, and the usage was harsh. I asked for a permission to buy new cables and some usable bag for them. The price tag made them thinking that these are serious stuff, and should be treated equally. I also love Velcros, as cables are much easier to handle individually than as a tangled mess. Edited July 21 by itu Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 21 Share Posted July 21 Another way to look at it is that the lead fuse reveals the current capacity of the wire, which must be equal to or higher than the current draw of the amp. That means you want the lead fuse rating equal to or higher than the amp fuse rating. You can't really go too high, but there's no point in going more than twice the amp fuse rating either. You can feel confident in ignoring the performance claims made by purveyors of leads that resemble fire hoses. 1 Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted July 21 Share Posted July 21 While I agree that there may be a marginal increase in safety if you fuse the cable to suit the equipment, the downside is that if you use that cable with another item of equipment, you run the risk of blowing that fuse at power up, and then having to fault-find while you are already stressed about setting up and sound checks. On that basis, I would fuse each cable to suit the equipment with the largest current draw, so you can swap them around without worry. David Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 21 Share Posted July 21 My assumption with a lead for an amp is it would be the only piece using it and dedicated to it. Which begs the question as to how the OP lost his. Maybe the missus is using it on the coffee pot? 🤥 1 1 Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 23 Share Posted July 23 On 21/07/2024 at 04:50, itu said: T = Träge = slow blow F = Flink = fast These are originally German terms. About the diameter of a cable: Usually it is safer to use slightly larger diameteter than that specified, if the cable is in active use. Here active means gigging round the country (and for some of you: the world). As cables will be bent a lot, at some time the copper will be chipped to smaller pieces and the ability to carry the specified current will be less. I have been amazed pretty often that so many bands have invested to equipment, but not to functional cables. When I joined one band long ago, their cables were just a mess in two or three plastic bags. Some cable was always missing, and the usage was harsh. I asked for a permission to buy new cables and some usable bag for them. The price tag made them thinking that these are serious stuff, and should be treated equally. I also love Velcros, as cables are much easier to handle individually than as a tangled mess. My understanding is that T is the designator for time lag or time delay or timed opening fuses. Looking at the IEC standards, there are T, TT (even slower opening), F and FF (even faster opening) but the TT and FF are specialty products that we won't see in the MI industry. These only apply to the 5mm x 20mm fuse type, the 6.3mm x 32mm fuses use different designators. 1 Quote Link to comment Share on other sites More sharing options...
itu Posted July 23 Share Posted July 23 2 hours ago, agedhorse said: My understanding is that T is the designator for time lag or time delay or timed opening fuses. What I remember from some age old papers, and collegial comments (when I was working in a broadcasting company), fuses had these abbreviations from German. I think there were some old norms/standards (DIN = Deutsche Institut für Normung) that were originally DIN and have been later updated to Europäische Norm (EN). That time lag sounds good, and easier to remember than Träge. My colleagues used the term slow blow, although that is probably not a standardized term. Quote Link to comment Share on other sites More sharing options...
BigRedX Posted July 23 Share Posted July 23 I think we've scared the OP off... 1 1 Quote Link to comment Share on other sites More sharing options...
BassAdder60 Posted July 23 Share Posted July 23 28 minutes ago, BigRedX said: I think we've scared the OP off... He’s blown a fuse 😂 1 Quote Link to comment Share on other sites More sharing options...
PaulWarning Posted July 23 Share Posted July 23 51 minutes ago, BigRedX said: I think we've scared the OP off... I'm not surprised, all they asked was a simple question, talk about making life difficult 🙂 1 Quote Link to comment Share on other sites More sharing options...
bremen Posted July 23 Share Posted July 23 Mr Horse's post was useful reference and should be pinned somewhere. Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 23 Share Posted July 23 11 hours ago, PaulWarning said: I'm not surprised, all they asked was a simple question, talk about making life difficult 🙂 What’s difficult about his question or the information that was provided? Often, a seemingly simple question doesn’t have a simple accurate answer and since the wrong answer (of an answer that’s out of context) can be dangerous, the additional information is in fact important. 2 Quote Link to comment Share on other sites More sharing options...
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