MCB advice, B-type to C-type

[dannyp]

here is a odd breacker related question.

is there any reason why once youv've triped a breacker for some while after they seem very easy to trip again but if you leave it and go something else for an hour or so they are back to normal. the more expensive ones crabtree ect the diffrence is less noticable but some of the cheep ones, where you were say running just over 100A before it triped rod after rod you'll be down to 80-85 A after

 

[WorkshopChris]

Yes basically they are a an elcctro thermal device. the cheaper ones will hold the heat for longer so are more prone to a re trip sooner.
Yes definitely differences between makes.
Used to specify Merlin Gerin, now Schneider.

 

[gaz_moose]

I bought a clamp meter, set it to A~ 200 and clamped it on the brown wire from the welder supply cable and set the machine to maximum.
I used the camera on my phone to record the meters display as it didn't have a 'peak hold' feature. it recorded 68.3 before it tripped the MCB I tried it again and got 70.8
I had enough 'weld time' to strike an arc/ melt a puddle in some 25x6mm flat ali bar it was only about the time I was due to dip the filler rod that it trips the MCB.

 

[WorkshopChris]

What how many amps does your meter show while the welder is turned on and you are not welding?

 

[brightspark]

that seems rather high on the input unless its a massive welder maybe on start up inrush but high once running

 

[gaz_moose]

its no bigger in size than the portamig 216 I bought last year.

just ticking over with the fan running is showing as drawing 00.2.

the machine suggests its a 180amp unit.

 

[gaz_moose]

is this a no-go then guys?

 

[WorkshopChris]

I used the camera on my phone to record the meters display as it didn't have a 'peak hold' feature. it recorded 68.3 before it tripped the MCB I tried it again and got 70.8

If you are pulling over 60 amp occasionally then its going to need re-looking at.
Guess you are going to need to talk to your electrician.

Hear goes for so ifs and presumptions and possibilities.

Probably preferred option.
If the board that supplies this is the main for the hole house then maybe replay your present outlet with a 50a RCBO ( lower than required but would leave some headroom on the main supply for the rest of the house.) Either hard wired or via a 63a plug and socket.

Or the budget option, try a 32aC and see how you get on, you might be surprised.

If your workshop supply is a sub board fed from the main one in the house then it might be a complete re work.

 

[gaz_moose]

View media item 9269
that is the consumer unit for my whole house which is in the garage (garage is on the side of the house). under it you can just make out the top of a piece of hardboard screwed to the wall which has the electric meter and the socket for my welder.

 

[brightspark]

its difficult to advise without knowing what the proper input amps should be rated at and what its actually pulling

 

[gaz_moose]

I totally understand mate. I just wish they could have put a data plate on the back. then i would know where i stand. i don't really want to splash out on having dedicated supplies etc.. put in as i plan on moving house in the not so distant future.

i don't have much call to play at being a welder these days so it only gets used every now and again so its a bit steep spending a grand or two replacing it for a shiny new toy.

ho-hum.. stick to my 1.2mm sheet work i guess!!!.

 

[WorkshopChris]

Ok its as convenient as it gets for your electrician to sort out, if your welder is designed to be pulling that amount of power and is not faulty then you need to see what he thinks. As the power requirements go up so do the associated risks.

i don't have much call to play at being a welder these days so it only gets used every now and again so its a bit steep spending a grand or two replacing it for a shiny new toy.

ho-hum.. stick to my 1.2mm sheet work i guess!!!.

See what he says but as its that close a change to 32A C and a posible cable upgrade might give you more scope for not a lot of money.

 

[brightspark]

if its close run a bit of 6mm from db to a double pole 45 amp switch hard wire in and change the breaker to a 40 amp . a few possibility's

 

[gaz_moose]

by "double pole 45 amp switch" i take it you mean like a rotary isolator?? i know its naughty but didn't put an isolator on it before as it really is about a foot away from the DB so i would just flick the MCB when not in use and unplug the commando.

so it would be something like,
commando socket
6mm cable
45 amp rotary isolator????
6mm cable
40 amp breaker. should we put a C type in?

am i ok to run it through the same RCCB as it is now or should we just fire a separate circuit in?

im not going to put it in myself as i wouldn't have a clue its just nice to know a 'bit'.

 

[123hotchef]

45A cooker switch would do wouldnt it?

 

[brightspark]

by rights the socket should be over 45 amp not a 30 that's why I said hard wire the welder in to the rotary isolator direct and do away with the socket its not needed

 

[gaz_moose]

gotcha,
i will leave this circuit in place as i use the plug for my mig etc.. and just get an additional circuit put in.

the tig only stays in the garage so hardwiring it is no real problem.

cheers guys.