Putting a 16A commando socket in my garage

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Hello everyone,

I have a single phase MIG welder which when run on full power draws just a little bit too much current for a 13A plug and it tends to use fuses if I don't weld in very short bursts. I intend to put a 16A commando plug on it instead.

Can I put a 16A socket as a spur off the 13A socket on the ring main in the garage?

Alternatively, the consumer unit is in the garage so it would be just as convenient to go from there instead. Can I add it to the 15A breaker for the immersion heater? Is that legitimate diversity, I'm unlikely to use the immersion and the welder at the same time.

Presumably, the 16A socket needs to be RCD protected? If I come off the ring main, that's already done but if I come off the immersion heater breaker then I'll mount the socket on a box with an rdc on it, yes?

2.5mm^2 T&E for this and steel trunking and boxes, yes?

Is this notifiable under part P?

Lots of questions! I did a degree in Electrical Engineering but they never taught us anything useful like the wiring regs!

Thanks everyone!
 
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You mustn't put it on a ring because the overcurrent protection is not suitable.

Putting it on the immersion circuit is also less than ideal, you say you are unlikely to use both at the same time but it's easy for something like an immersion heater to get left on every so often. If the immersion heater is only used as an emergency backup i'd say it's probablly ok but still less than ideal.

Also if the breaker on the immersion heater circuit is a type B (or the old equivilent of a type B) you may have trouble with it tripping when using the welder.

What is the layout of your consumer unit? is it a type you can still get breakers etc for?

Adding it on it's own circuit. Adding it on the immersion circuit is open to interpretation (is the immersion circuit a radial circuit? i'd say no it's a single applicance circuit).
 
you avoided mentioning the input power rating of the welder. what does it say on the makers plate and the instruction book?
 
Welding equipment generates large amounts of electrical noise which you need contain in the garage wiring as far a possible. It can play havoc with reception of digital TV and radio if it gets anywhere near the wiring ( power or aerial ) for the TV.

So connecting to cable that also supply the house is NOT a good idea.

The cable to the immmersion heater would be more of a problem as the earth in that cable is connected the tank and pipe work. That connection forms a path for electrical noise on the welder's earth wire to flow to earth through the house. Not a safety hazard in any way but it could possibly increase disruption to radio and TV reception.
 
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Hey, thanks for the replies.

Welder is rated at 15A and (from memory) the manual recommends hard wiring or using a 16/32A plug

Just been out to have a look and the ring in the garage is on a 16A mcb so looks like it would be suitable as regards protection for a 16A socket but not a good idea as I have a washing machine and air compressor on that circuit too.


I am sufficiently confident that I'll never use the welder and the immersion at the same time to make it a viable option but there is a single slot left for a new breaker and looks like I can still get them. RS have a 16A Type C which will match. (Although I never had any nuisance tripping from the 16A Type B it was on before so should I stick to Type B?)

The other complication is that the board doesn't have any RCD protection (when I posted last night from memory I assumed there would be) so should I try and find an RCBO that will fit the CU or can I use an RCD at the box with the socket mounted on it? I'm assuming 17th ed says it has to have RCD protection at the CU, not at the socket. Is that correct?


Good point re: RF interference in the ring but if I come off the immersion circuit straight from the CU then that is no different RF-wise than having a separate circuit.

What I propose to do is share the 16A immersion breaker and fit an RCD at the socket unless anyone has any thoughts why this is definitely a no-no.

Alternatively, I fit a 16A RCBO (or MCB with an RCD at the socket?) for a new circuit but that means lots of dicking around in the CU to make space for it - it's a bit of a rat's nest in there.

Thanks again.
 
I think a new 16A type C breaker is the way to go - there's no point installing a type B when you know that there's the potential for high inrush currents, and as it's a new circuit, achieving the required Zs shouldn't be particularly difficult.

How far is it from consumer unit to the proposed location of the 16A outlet?

As for RCD protection, it depends on a number of factors. The 17th Ed. requires all socket outlets rated at 20A or less and intended for general use to be protected, although I don't think you'd really fall foul of this one. All cables concealed in a wall at a depth of <50mm also need to be RCD protected unless run in SWA or have an equivalent earthed metallic protection, such as galv metal conduit. If the cable is to be clipped direct or in trunking/conduit, RCD protection is not required.
 
If it's not required to have RCD protection then I'll put a new 16A Type C in and and rcd on the socket. Was reluctant to use RCBO because it looks a bit crowded in the CU.

Only about 2 metres from the CU to the new socket so Zs should be pretty low.
 
Er you have of course got permission from your DNO to connect welding load to your supply?
 
Do you need to? I've got 16A and 32A sockets in my garage which get used for welding as well as some other big inductive loads. :confused:
 
Er you have of course got permission from your DNO to connect welding load to your supply?

Is this really a requirement for small welding loads? It's news to me. In any case, I can't imagine many people are going to bother, especially as you can pop down to your local B&Q or Argos and buy a portable welder these days.
 
Is this really a requirement for small welding loads

Unfortunately yes, as well as all single phase motors over 1hp. (the motor in some Dysons is higher than this!!)

Does it need to be? I don't know. Put we have had complaints of flickering lights from customers living next door to someone using a plug in welder from B&Q
 
They're having a laugh if they think I'm going to write to them for permission to run a portable air compressor, welder, or even a large hoover on my supply..
 

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