Grid switch ratings enquiry

Chris Pearson:

So what do we mean by the word, "rating" which is in the subject heading?

In this case, surely we are talking about the "Rating of the double socket-outlet". It would make no sense for the marked rating of "13 A" to mean "2 x 13 A", especially given the tests in the standard.

If MK states that it's twin sockets may supply a combined current of 19.5 A continuously, why are they not rated at 19.5 A? If such ratings were applied, purchasers might choose to buy the sockets with a higher rating so competition might drive up the quality.

I don't know, perhaps some are ... just the Logic Plus ones I have are rated 13 A, as are most double socket-outlets I see. Which ones are you talking about, and what is the rating marked on the back in accordance with the standard? It makes no sense for the socket-outlet to be rated less than the manufacturer states it's rated for?


However, it's still not "26 A" or "2 x 13 A" is it?

If a multiple socket-outlet may safely supply only 13 A, why are they not required to have a 13 A BS 1362 fuse in them?

This has already been explained in another post. It's no different than an unfused double adaptor being used with a single socket-outlet.

The 1984 version of the standard is the same as the current one as regards labelling. Unfortunately, the original 1947 standard is not downloadable from the BS site.

Agreed

I am tempted to put a clamp meter on the circuit when both washing machine and tumble drier are running.

I can tell you what you will see for domestic machines, which is as follows:

On high heat, the tumble dryer will use about 1-2 A when only the motor is running, and 11-12 A when both parts of the element is switched on. Depending on the weather (temperature and humidity), and how damp the clothes are, the highest current is drawn between 40 and 80 % of the time.


The washing machine (washer only - not washer-dryer) is roughly similar - slightly more motor current on spin - but only draws its full power of approximately 11 A when heating. On a boil wash in winter, time to get to temperature can be a considerable time. However, on most cycles in use, I'd guess the heater on a modern machine is on for about 10 minutes at most.


A dishwasher heater is on for longer - especially where the machine has a drying cycle at the end also.


So, in a domestic situation, you will get about 24 A for periods of 10-30 minutes at a shot, probably meaning many double socket-outlets would deteriorate in a couple of years at most, dependent on usage - greater risks in winter.

Commercial / industrial usage is a very different kettle of fish.

 

Chris Pearson:

So what do we mean by the word, "rating" which is in the subject heading?

In this case, surely we are talking about the "Rating of the double socket-outlet". It would make no sense for the marked rating of "13 A" to mean "2 x 13 A", especially given the tests in the standard.

If MK states that it's twin sockets may supply a combined current of 19.5 A continuously, why are they not rated at 19.5 A? If such ratings were applied, purchasers might choose to buy the sockets with a higher rating so competition might drive up the quality.

I don't know, perhaps some are ... just the Logic Plus ones I have are rated 13 A, as are most double socket-outlets I see. Which ones are you talking about, and what is the rating marked on the back in accordance with the standard? It makes no sense for the socket-outlet to be rated less than the manufacturer states it's rated for?


However, it's still not "26 A" or "2 x 13 A" is it?

If a multiple socket-outlet may safely supply only 13 A, why are they not required to have a 13 A BS 1362 fuse in them?

This has already been explained in another post. It's no different than an unfused double adaptor being used with a single socket-outlet.

The 1984 version of the standard is the same as the current one as regards labelling. Unfortunately, the original 1947 standard is not downloadable from the BS site.

Agreed

I am tempted to put a clamp meter on the circuit when both washing machine and tumble drier are running.

I can tell you what you will see for domestic machines, which is as follows:

On high heat, the tumble dryer will use about 1-2 A when only the motor is running, and 11-12 A when both parts of the element is switched on. Depending on the weather (temperature and humidity), and how damp the clothes are, the highest current is drawn between 40 and 80 % of the time.


The washing machine (washer only - not washer-dryer) is roughly similar - slightly more motor current on spin - but only draws its full power of approximately 11 A when heating. On a boil wash in winter, time to get to temperature can be a considerable time. However, on most cycles in use, I'd guess the heater on a modern machine is on for about 10 minutes at most.


A dishwasher heater is on for longer - especially where the machine has a drying cycle at the end also.


So, in a domestic situation, you will get about 24 A for periods of 10-30 minutes at a shot, probably meaning many double socket-outlets would deteriorate in a couple of years at most, dependent on usage - greater risks in winter.

Commercial / industrial usage is a very different kettle of fish.