What BSEN numbers for these breakers?

Goody · Apr 9, 2012

Hi,

Could someone shed some light on the BSEN numbers for the breakers shown on the picture. Many thanks.

[ElectriciansForums.net] What BSEN numbers for these breakers?

Kenny. · Apr 9, 2012

Goody said:
Hi,

Could someone shed some light on the BSEN numbers for the breakers shown on the picture. Many thanks.

View attachment 11779

Dorman Smith Loadmaster BS 3871 Part 1 http://www.dormansmithswitchgear.com/tec_support_downloads/mcb/Loadmaster_datasheet.pdf

Des 56 · Apr 9, 2012

lamb said:
Crabtree C50, should be BS3871. And the main switch is probably a BS5419.

I am going to disagree
At first glance I was thinking crabtree c50 but Kenny mentioned D S and I agree
I think the c50s were a little narrower

lamb · Apr 9, 2012

I think you're right, I only glanced the picture

Dunc · Apr 9, 2012

Rule of thumb is if it's old with a Type number it's a 3871 if it's newer with a Type letter it's a 60898.

e.g. Type 1 and 2 = 3871 , Type B, C, D = 60898.

Also if it's rated at 5A, 15A or 30A it's generally a 3871 as the newer 60898s are rated at 6A, 16A or 32A. No idea why they upped the rating slightly on the newer breakers though.

telectrix · Apr 9, 2012

No idea why they upped the rating slightly on the newer breakers though.

think it was originally to try and make the protection as near to that of the fuses they replaced, as MCBs are quicker reacting than fuses.

Knobhead · Apr 9, 2012

Which ever they are, they want binning ASAP.
They are magnetic/hydraulic where as modern breakers are thermo/magnetic. Not very sensitive to prolonged low-level overload.

E54 will probably give more details.

londonlec · Apr 9, 2012

Definitely BS3871.

I replace a lot of these for a London LA.

Watch the max Zs's... they are very low.

Engineer54 · Apr 9, 2012

They look like the DS breakers, based on the USA design. They were out and out crap when they were first introduced and are still crap today!! They don't give a very close protection, better than a rewireable fuse but not that much better!! lol!! The old C50 breakers are not much different either!! These CU's and the breakers need binning whenever possible and replacing with up to date equipement!!

The reason for the 6/ 16/ 32A etc values over the old 5/ 15/ 30A etc values, is purely for our old friend ''harmonisation''...

mogga · Apr 10, 2012

they are Dorman LM and as E54 says they should be BINNED i have in the past argued that "live exposed parts" only to have " by use of tool " throw that argument out these dbs are downright dangerous and IMHO should be replaced ASAP that argument aside they do comply but Zs are guff and this gives reason for replacement more that acctual physical construction

Engineer54 · Apr 10, 2012

The Zs is high because they are type 3 or 4, totally unsuitable for domestic use in most circumstances!! Add to this a course sensitivity compared with the more modern MCB's and you have even more reason to get shot of them!! lol!!