Vintage Bulgin mains connectors & safety

[Tony L]

I was watching this video from Rift Amps yesterday (I own one of their combos) and the point was made that Bulgin connectors are now effectively illegal as they will fail any PAT test. Chris was very forceful on this point in the video implying that if he returned any amp to a customer with one he could be legally liable.

I’ve since googled this and he appears to be correct. The reason being that a Bulgin mains plug can be unscrewed without tools when live (even when fitted in the back of an amp).

I’ve always felt they were highly dangerous and would never use a guitar amp with one for gigging. In fact one of my earliest memories of guitar amps was getting electrocuted from a cracked Bulgin plug on the back of some ancient amp head (not mine, can’t remember what it was). I think we need to work on the assumption that it is illegal to sell equipment fitted with Bulgin mains plugs as working. Still ok to sell as ‘parts/for restoration’ etc, but I have a feeling there is potential liability for selling kit as working.

This applies to so many vintage amps and I assume not only the full-sized Bulgin plugs used on Leaks, Quad ESLs, Radfords etc but also the mini-Bulgins used on Quad 3-Series, Naim 120s etc.

Conversion is not hard. There are some IEC mains sockets that will fit into a Bulgin cut-out without drilling, and mini-Bulgin could be converted to captive mains lead with nothing more the appropriate size cable gland/clamp, i.e. in a non-destructive reversible way.

Certainly something to think about. That said I’m still happy to use ones I have built and fully inspected myself at home. If I had kids or anyone else messing around with my stuff etc I’d change them.

PS There is a possibility that the side-entry type of mini-Bulgin plugs (often used with Quad 303s etc) may still be legal as they are held together with screws, i.e. they can not be opened by hand. I still don’t think they’d pass a PAT test as I don’t think they are even on the list of things to test, but conceptually they are certainly better.

 

[Nagraboy]

Isn’t there a newer type of Bulgin plug that’s legal up to a few amps rating? Designable sell them.

 

[Barrymagrec]

There were later versions of the mini-Bulgins that had screw fitted shrouds and cable strain relief, both right angle and straight but that doesn`t get over the small finger pokability issue.

Personally I won`t be changing them on any equipment I have but then I don`t have any small kids floating about.

As an aside, standard Bulgin`s get very hot and eventually disintegrate if used to power a triple deck 16mm mag film recorder and associated Siemens projector - not recommended.

 

[ampedup]

With my Bulgin connectors (Quad II), I wrapped the body and two inches of cable with stretch silicon black tape, which provides strain relief and make them impervious to being fiddled with.

 

[Tony L]

I’m absolutely confident in mine (pictured above). They have the very seldom seen military rubber cable strain-relief, which is a very tight fit over the cable I used and has an integral grommet that keeps it locked firmly in the bakelite part. As such the cable can’t pull out of the plug, so it only fails safety on a child unscrewing it level, which couldn’t be more irrelevant to me.

My concern here is as someone with a view to the conservation of vintage audio and other electronic devices (computers, vintage test gear etc). This effectively condemns them to landfill if donated to charity etc. If it fails a PAT test it goes in the skip. Be very aware of that and make sure you only leave such kit to people who understand it, can make it safe etc. Conversion is easy. You don’t even need to drill the case. I don’t want to do mine now as it poses zero risk to me and I like the vintage aesthetic. As I say if I had kids, my cat grew thumbs or whatever I’d think differently. If I ever sold them I’d convert them as I’d obviously want to sell as fully restored and working, which Chris (the Rift Amps guy) suggests is no longer legal.

PS A Bulgin mains connector is IIRC a 5A rating. The mini-Bulgin I think a 3A. It should never get hot! I’ve certainly never seen one even get warm, even in big guitar amps (i.e. no warmer than the surrounding amp casework). Hi-fi kit such as the Leaks, Quads, ESLs draw an Amp or two max. I have 1A fuses in my TL12 Plus amps and 3A in the mains plug. The 303s have a 2A internal fuse and 3A in the plug. None of this is high current stuff. If a mains connector is getting hot anywhere something else is very wrong IMO.

 

[Barrymagrec]

PS A Bulgin mains connector is IIRC a 5A rating. The mini-Bulgin I think a 3A. It should never get hot! I’ve certainly never seen one even get warm, even in big guitar amps (i.e. no warmer than the surrounding amp casework). Hi-fi kit such as the Leaks, Quads, ESLs draw an Amp or two max. I have 1A fuses in my TL12 Plus amps and 3A in the mains plug. The 303s have a 2A internal fuse and 3A in the plug. None of this is high current stuff. If a mains connector is getting hot anywhere something else is very wrong IMO.

Yes, I was being a little facetious, the problem in this case was a very badly thought out system that ran the projector with it`s 1000 watt lamp through the same mains input as the film recorder with a total of 7 largish motors plus the electronics and a pair of selsyns.

 

[Beobloke]

I was watching this video from Rift Amps yesterday (I own one of their combos) and the point was made that Bulgin connectors are now effectively illegal as they will fail any PAT test.

The reason the amplifier will fail a PAT test is only because of the lack of connection between the mains connector and the main chassis, as it is reasonable to treat it as a Class I item given the exposed metal chassis at the rear. If you were to treat it as a Class II assembly, it would still pass in its original state (although I personally wouldn't do that!)

However, this is purely to do with the internal wiring configuration and nothing to do with the style of the connector and socket itself. The only steps taken at the beginning of a PAT test before the actual electrical tests are a visual inspection for condition and cleanliness of the item, plus a check for a correct fuse in either the equipment or the lead - it's this last one that many PAT testers miss! It must also be remembered that the lead and the item are treated as separate entities and both tested independently.

Therefore, if he had left the original Bulgin connector in there, but terminated the existing connector earth wire to the chassis and then added a new wire between chassis and connector, then both the item and the lead would pass a PAT test with no problems, assuming of course that the Bulgin socket on the lead is in good condition.

Obviously, the design of the socket on the lead is not exactly brilliant and being able to undo it whilst plugged in and live is one of those dodgy ideas that should be filed under 'experience to learn from', but as long as the connector is tightened up correctly, undamaged and in good condition, it will still pass a PAT test.

As an aside, one needs to be VERY careful about earthing things that were not originally earthed, even though it ostensibly seems sensible. Many Dansette type record players use a live chassis configuration for their internal amplifiers, and I've encountered people who have earthed them "for safety" and then wondered why their house RCD trips every time they plug the thing in.

 

[Tony L]

The reason the amplifier will fail a PAT test is only because of the lack of connection between the mains connector and the main chassis, as it is reasonable to treat it as a Class I item given the exposed metal chassis at the rear. If you were to treat it as a Class II assembly, it would still pass in its original state (although I personally wouldn't do that!)

I’m not convinced that is true as there is no conceptual difference between the way the Bulgin plug is secured to a chassis and a modern IEC connector. Both are electrically isolated and attached with two screws/bolts. The internal earthing is equipment specific.

My suspicion is the Bulgin socket (amp end) is absolutely fine, but it is the plug (cable end) that can’t possibly pass a PAT test as it can be easily opened whilst live with no tools. Without a legal plug the socket is obviously useless. Picture a situation with a pair of ESLs in a room with a small child. The top cap of the Bulgin plug could very easily be unscrewed by the child exposing live 240V terminals. No way in hell will that construction pass modern electrical safety legislation.

It is hard to find proper legislative evidence here. I can find a fair few music forums suggesting they are now illegal, but nothing pointing to legal paperwork. They are a very common connector on highly prized vintage Vox, Marshall, HiWatt, WEM etc guitar and bass amps.

If anyone has a link to current UK or EU regulation either proving or disproving this please post it! I’d really like to get the facts right here. My suspicion is Chris Fontana at Rift has this one exactly right. It is after all his job, his potential liability etc.

PS Following the above thinking I’d expect a one-piece moulded Bulgin cable similar to a modern one-piece moulded IEC cable would be perfectly legal. I’m surprised no one is making them! That would be the perfect solution to my mind as it would require no modification to the amp and the original plug could be retained for collector value.

 

[Barrymagrec]

PS Following the above thinking I’d expect a one-piece moulded Bulgin cable similar to a modern one-piece moulded IEC cable would be perfectly legal. I’m surprised no one is making them! That would be the perfect solution to my mind as it would require no modification to the amp and the original plug could be retained for collector value.

Such a cable would still not meet the exposed live conductor requirement.

 

[hp1]

I used these on a lighting gantry we had for our mobile disco, I was rushing a bit and as the L and E moulding bit was so crap wired them the wrong way around then proceeded to grab the gantry while the lights where on . I was stuck there getting a good dose of 240v for about a minute and my whole right arm ached for 3 days afterwards.

 

[Tony L]

Such a cable would still not meet the exposed live conductor requirement.

It isn’t exposed as such, but you could certainly stick something conductive in there as it is not recessed by much. Pretty sure they don’t make the earth connection in advance of live/neutral when being plugged in, and I bet that is a current regulation too.

 

[Beobloke]

I’m not convinced that is true as there is no conceptual difference between the way the Bulgin plug is secured to a chassis and a modern IEC connector. Both are electrically isolated and attached with two screws/bolts. The internal earthing is equipment specific.

Exactly, that’s why the internal wiring modification he did IS necessary to pass a PAT Test. It’s the wiring that is the issue, not the socketry.

 

[Beobloke]

My suspicion is the Bulgin socket (amp end) is absolutely fine, but it is the plug (cable end) that can’t possibly pass a PAT test as it can be easily opened whilst live with no tools.

it doesn’t matter if you can open it easily. The PAT test is not a design assessment or verification. It’s a functional safety test. If the Bulgin socket is in good condition, correctly wired and done up properly at the time of the test, then it will pass, by the rules of the test.

Whether it meets modern electrical safety regulations is a different issue.

 

[stevec67]

As a private individual you are a allowed to sell stuff that doesn't meet current regs. Not a trader. So furniture needs its fire retardant tags if a trader sells it second hand, but you or I can sell it because we aren't expected to know any better.