Please could someone point me towards something that explains how to design two MCBs in series but provide adequate discrimination. The scenario, is you guessed it, a shed. 16A MCB in Shed. I think the answer is 32A but the cable sizing only just manages that so would prefer to have 20A upstream. Or reduce the MCB in the shed... 20A upstream and 10A downstream but unnecessary restrictive (although within expected demand) and 10A into a double socket doesn't feel right. I can't make head nor tale of the Wylex MCB chart; i'm sure it's trying to tell me something. Thanks in advance
c20 in house, if that still complies, and b16 and b6 in shed? Or, b16 in the house and b20/b6 in the shed. In fact theres loads of way to sort it.
What size cable have you got feeding the small DB? Length of run? As mentioned 32A at house and 16A/6A at small db end sounds good to me.
If using earth wire and SWA as earth, why would 32A at house not be ok for 25m ? You won't be able to overload it, except with fault. As 'lectrician' said, most likely pop both ends anyway. If 10A is with shed design, I would go for that, best chance. If it pops, it pops. 'Course, I ain't an electrician(I've heard that somewhere before....!!!) Mr. HandyAndy - Really
what about 16A in house supplying sockets, run through 20A DP switch if isolation required then install fused connection unit for lights. That's what i'd do
....or straight from the DB(16A+6A) in the shed to a 13A FCU for sockets, 3A FCU for lights ? 16A max. 20A in house. ?? Mr. HandyAndy - Really
'Course, I ain't an electrician(I've heard that somewhere before....!!!) At this rate, dear, you're likely to hear it again.... Lucia.
Ah, that's sounds like you have some misgivings about the above suggestion! Which are...? Mr. HandyAndy - Really
Not at all, Andy dear. I think that all your ideas are absolutely wonderful. I don't know why Screwfix don't have a separate Mr. Handyandy - Really Talk Forum - really..... Lucia x
Why so complicated?? Straight forward installation as far as i can see. RCD protected 20A breaker at the house, supplying a garage DB with a 16A mcb for the socket and a 6A mcb for the lighting. In this instance no other local isolation is required, as the DB breakers are both local and in line of sight....
Not at all, Andy dear. I think that all your ideas are absolutely wonderful. I don't know why Screwfix don't have a separate Mr. Handyandy - Really Talk Forum - really..... Lucia x :^O brilliant lucia :^O
Why so complicated?? Straight forward installation as far as i can see. RCD protected 20A breaker at the house, supplying a garage DB with a 16A mcb for the socket and a 6A mcb for the lighting. In this instance no other local isolation is required, as the DB breakers are both local and in line of sight.... QUOTE^^^^^^^ And the title of this thread is????
Lectrician, He's probably not going to achieve total discrimination, with any MCB set up of the same type is he, under short circuit conditions?? So what are you trying to say??