Diversity Table A2 OSG P118

[CDB]

Morning all,

Thumbing through the OSG guide today and I have a couple of questions regarding the above table.

Firstly, just a idiot check but electric showers would fall into no.5 water heaters of the instantaneous type. I know this but so often doubt myself.

Secondly, No. 9. Am I right that this would be applied across all circuits to see if the main switch and supply are big enough. Its thrown me because if that's correct I would expect it to be last in the table.

Thirdly, No 10. Good old socket outlets. When would this apply if we typically using the standard 'socket outlet' circuits. Could I apply this in a workshop where I have a welder that takes a 16A C-Form connection on a radial with other outlets e.g to a fan? If someone could provide an example that would be great.

Thanks

Chris

 

[Pete999]

Morning all,

Thumbing through the OSG guide today and I have a couple of questions regarding the above table.

Firstly, just a idiot check but electric showers would fall into no.5 water heaters of the instantaneous type. I know this but so often doubt myself.

Secondly, No. 9. Am I right that this would be applied across all circuits to see if the main switch and supply are big enough. Its thrown me because if that's correct I would expect it to be last in the table.

Thirdly, No 10. Good old socket outlets. When would this apply if we typically using the standard 'socket outlet' circuits. Could I apply this in a workshop where I have a welder that takes a 16A C-Form connection on a radial with other outlets e.g to a fan? If someone could provide an example that would be great.

Thanks

Chris

16Amp socket on it's own circuit imo, if it takes 16Amps no diversity, a fan on the same circuit not good practice imo

 

[CDB]

16Amp socket on it's own circuit imo, if it takes 16Amps no diversity, a fan on the same circuit not good practice imo

Not even if you stick it via FCU at 3amp?

 

[Pete999]

Not even if you stick it via FCU at 3amp?

Not really

 

[CDB]

Why?

The welder will run off a 13A plug top but prefers 16A connection for full power work at which point it has a 40% work cycle.

And in which case then - when would 10 apply?

Sorry if I'm being stuuupid.

 

[Pete999]

Why?

The welder will run off a 13A plug top but prefers 16A connection for full power work at which point it has a 40% work cycle.

And in which case then - when would 10 apply?

Sorry if I'm being stuuupid.

If you try and run a welder rated at 16Amps from a 13 Amp socket you are asking for trouble, sorry to be so blunt.

 

[Wilko]

I agree with Pete - a 16A socket, a 16A welder and a 16A MCB that's your lot. If the radial is 2.5 clipped direct why not increase to 20A MCB perhaps? For my humble workshop I added a length of 2.5 to make a 32A RFC and no more worries

 

[stevethesparks]

Most small welders are supplied with 13 amp plug. I assume the manufacturers have calculated that full load is for a minimal time (due to the duty cycle) and is safe.

 

[westward10]

Treat the 16A socket as such and ignore the welder you cannot use that in diversity calculations.
I know it is acceptable to connect 16A EN60309 sockets through 20A devices but I would only apply this to multiple outlets and not a single socket.

 

[Pete999]

If it's rated at 16Amps then that's you're guideline

 

[CDB]

Thanks guys.

Lots of interesting takes on the welder problem. SteveTheSpark is right and when I bought the welder he offered to change the 16A connection to a 13A plug but I said it was OK and that I knew a tame electrician who could install a 16A for me.

If we put the welder problem aside. When would you be looking at No 10 to calculate diversity. To save you looking it up it says Socket Outlets - 100% of current demand of largest point of utilisation + 40% of current demand of every other point of utilisation.

Thanks again. As a self employed new spark its good to chew the ears off more seasoned experts and get different takes on a regulation etc.

 

[static zap]

Most small welders are supplied with 13 amp plug. ..... calculated that full load is for a minimal time .........

Look about at the contents of a few welder 13A plug fuse holders .
( You may be enlightened ... or the trail of discarded blown 13A fuses ) They take 26A to blow softly , just under to last a DAY/Week !

 

[CDB]

That doesn't surprise me at all. When I was reading about which welder to get they talked about replacing the plug regularly because it was designed to operate at the load demanded by the welder and they degrade!

Would it be right to say the manufacturers are knowingly abusing 13A plug tops in order to sell hobby welders?