M.C.B'S

MUST BE SOME ELECTRICIANS HERE . I'm doing a lot of alterations to my workshops. upgrading. as it is now I have a ten way consumer unit for the house and on this I now have a 63 amp mcb to supply power to another consuimer unit in my workshop. now with all the extra machinery I have I need to go up to 80 amp mcb. the problem is that the 80 amp mcb I've been given is plus half as wide as the others......I was told once you jump up to 80 amp mcb's this is so. the problem is I cant fit it in place of the 63 amp without taking one of the others out so making it a 9 way consumer unit . the question is ... do 80 amp mcb's exsist that are the same width as the the smaller mcb's. have I been mis-sold or mis-informed about the 80 amp I already have. the rest of the mcb's are Hager model number 6000-3...the type that tighten onto a buzz bar in the consumer unit. All the best...mark

Reply to
mark
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I'm not an electrician, but I've got two consumer units - the electric board put a splitter in after the meter. One goes to the house consumer unit, the other to the new consumer unit.

This saves taking the feed from an MCB, and has the added advantage that consumer unit no. 2 won't trip no. 1 as well as itself (all them clocks to reset etc.)

80A sounds like a lot for a domestic workshop - are you running a furnace/kiln or something like that?
Reply to
Duncan Munro

DUNCAN SAID "80A sounds like a lot for a domestic workshop - are you running a furnace/kiln or something like that?"

Things like plasma cutters and 14cfm compressors dont half draw current together with 1400 watts of lights......and what ever else I may have switched on at the same time . the comp draws up to 45 amps starting then uses a continuse 19 amps.....the plazma cutter is used at the same time as the comp. im just covering for extreems. may end up putting another box in if i cant find a slim line 80 amp mcb. all the best.mark

Reply to
mark

Ouch!!! Good luck ;-)

Reply to
Duncan Munro

Mark, I am just curious but you must have one hell of a compressor, my first one was a single cylinder industrial with a 3hp motor single phase and starting on load I thought 20 amps was high. My brother also has a plasma cutter but his garage does not rate as high as yours does?

Martin P

Reply to
Campingstoveman

martin said "Mark, I am just curious but you must have one hell of a compressor, my first one was a single cylinder industrial with a 3hp motor single phase and starting on load I thought 20 amps was high. My brother also has a plasma cutter but his garage does not rate as high as yours does?

Martin P"

It says on the plate on the compressor motor 2.2 kilowatt and 14.6 amp. I was measuring the power with one of those inductive clip-on ampetres....ON ONE OF THE TAILINGS COMING FROM THE METER TO THE CONSUMER UNIT . There is a 60 foot run of 6mm cable to my workshop ....thinking about doubling this up to, 2 x 6mm The ampmetre ..(a fiends) .has nmisled me before ......with devices that use motors and tranformers......it said my three phase rotary converter was using 14 amps ........but when I did the calculations the old fashioned way by counting the turns of the dial on the electricity meter ,My maths showed I was actually using about 2 amps or so. anyhows not had the 63 amp mcb trip on me yet .....so perhaps I'm best leaving things alone.....until I do have a tripping problem. but I still dont know if there is a slim version of the mcb I talked about. ......will have to do some old fashioned counting turns of the meter with this compressor I think...... all the best ..mark

Reply to
mark

I think there's your own answer. If it's not causing a problem, why worry?

1500 W sounds like a frightening amount of lighting

Your compressor motor will draw 80 Amps or so *Momentarily* when starting. That doesn't mean everything has to be rated for that current. Domestic mcb's will cope with a fair degree of momentary overload to cater for motor starting etc. I'm not an electrician, but I believe that if you do have a problem with tripping on motor starting, there's a type of mcb which is specifically intended for motor starting duties, and will cope with a heavier momentary overload.

I have the dry-dock with a 5hp compressor (takes maybe 150 A to start), 300A MIG welder, 180A stick welder, plasma cutter, plus

3-phase convertor in the workshop running a lathe with 8hp motor + several smaller machines, etc., ALL on one 45A *cartridge fuse* from the main consumer unit. I haven't blown the fuse once in 5 years, I did have problems with a 45A mcb triping when the compressor started. That was a real pain as the two are 200m apart. All the individual circuits have mcb protection.

I should add that, apart from the compressor, I'm the only person who uses the heavy kit so it isn't all used at once

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Reply to
timleech

In article , mark writes

(Snip)

Mark,

You seem to be starting a new thread for each followup you post to responses to your original post.

That makes it very difficult for everyone else to read. It's much better practice to keep the conversation in one thread (which is kind of the point of having threads!).

Cheers

Reply to
Nigel Eaton

Mark, The only thing that concerns me is that you appear to be so over rated on the MCB that if you did have a problem it would not trip and at worst the faulty unit would over heat.

Martin P

Reply to
Campingstoveman

NIGEL SAID ..... "Mark,

You seem to be starting a new thread for each followup you post to responses to your original post.

That makes it very difficult for everyone else to read. It's much better practice to keep the conversation in one thread (which is kind of the point of having threads!).

Cheers

Reply to
mark

Tim said

"there's a type of mcb which is specifically intended for motor starting duties, and will cope with a heavier momentary overload."

Yup I have them .....they are "D" types. yes thanks to my friends inacurate ampmetre .....I think I am overestamating what I use . something to do with inductive devices (motors transformers) confusing the thing I think. sorry about the postings being all over the show.......but it's the only way I can post for now .....see other reply to Nigel all the best..mark

Reply to
mark

Agreed I don't think 80A MCB would give very good protection for 6mmsq cable, even the current 63A is pushing it somewhat :-(

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Reply to
timleech

Mark, Have your tried using a different mail packages for mail and news. For historic reasons I use netscape for mail and that also suited me for news until I wanted a filter on the news to reject the utterings of a certain frequenter of this NG. I then enabled OE for news only, used a dummy address for the return addy. I've been usuing this since around Christmas with no obvious problems.

HTH

Bob

Reply to
Bob Minchin

IIRC the usual domestic supply is only rated (and fused) at 60A anyway?

Reply to
Roland and Celia Craven

bob said Mark, Have your tried using a different mail packages for mail and news. For historic reasons I use netscape for mail and that also suited me for news until I wanted a filter on the news to reject the utterings of a certain frequenter of this NG. I then enabled OE for news only, used a dummy address for the return addy. I've been usuing this since around Christmas with no obvious problems.

HTH

Bob

Think if someone were to set up a web forum as good as the american run. machine shop forum "practical machinist"

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would be on to a winner.....mr certain frequent user could be banned as soon as he made an apearence. what would be better though .......if google stopped this bloody delay. all the best....mark

Reply to
mark

In article , mark writes

Blimey, now you're following up to replies in completely different threads!

I have to say, that combining that with your software not quoting replies in accordance with the RFC's (i.e., there should be a ">" character at the beginning of each quoted line), your replies are pretty much incomprehensible without a deal of work.

I would really, really suggest that you get some decent posting software and a good posting host. Sign up with news.individual.net. It's free and provides an *excellent* service.

You can then either continue to use Outlook Express, in which case I'd recommend you google for Quotefix as a way of sorting out some of the bugs in OE, or switch to something like Free Agent

formatting link

If not, I fear you'll be hitting a lot of kill files in the near future, and that would be a shame.

Reply to
Nigel Eaton

NIGEL

just downloaded free agent and my server will not allow it by the looks of things

Maybe it's because im subscribed to text only on my outlook yes I could have it the other way ..but ...it does not work at all well with pipex ,messages other than text in the news groups in my outlook take 3 or four mins to download ...and that just for each message ...so thats why I went text ...pipex have had this probl;em for over a year now....EVERYONES PROBLEM NOT JUST MINE....... other than news group troubles pipex has been spot on for me ...so dont advise to change my server.

tried three or four times to reply and just got this all the time.

18/04/2004 00:16:49 Connection closed unexpectedly by server.: Connecting to pop.dsl.pipex.com.

I've only got a limited amnount of patients with this. and i believe in a stress free life ....... i think computers were invented to shorten peoples lifespans .....it aint doing it to me . will try again tommorow just in case its a glitch ..and thats me lot. all the best...mark

18/04/2004 00:16:49 Connection closed unexpectedly by server.: Connecting to pop.dsl.pipex.com.
Reply to
mark

Ours is 100A, they uprated it from 60A about 10 years ago, without being asked, when the meter boiard had to be replaced (it had turned to dust!)

I guess you'll find 100A ir normal for newer installations.

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Reply to
timleech

A few comments..

If the workshop is drawing more than 63 amps you probably want to separate the supply anyway as putting on the oven to cook dinner could pull the master trip for both the house and the workshop ( Workshop 60 A +House 45 A = 100 amp breaker trip out :-( )

Your cable is probably rated at 69 A , and you should ignore brief surges such as motor starting, as the rating is based on not overheating the cable in continuos use, and a brief surge ( within reason ) will not heat a cable significantly.

I presume your using single phase, even so the draw for your compressor seems a little high.

For a small workshop you seem to have a lot of light... do you also have electric heating.... would night storage save on capacity required and cost.

If you are the only person in the shop load will not ever be the total maximum. Have you worked out your worst case load ?

I'm a little rusty on the regulations, but IEE 16th Ed had rating allowances for part use written into it somewhere.

Jonathan

Barnes's theorem; for every foolproof device there is a fool greater than the proof.

To reply remove AT

Reply to
Jonathan Barnes

If it's ordinary flat twin & earth, the rating (usually?) quoted is

40A for 6mmsq - see for instance
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Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Reply to
timleech

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