comsumer unit advice for a 110v system

[rizred]

Hiya,

I have been approached by a customer to provide a small "IT" trailer. The trailer will have a data cabinet with a small server 1 or 2 pc's.

The trailer will have two 200amp hr batteries running an inverter to take the power to 110v - the customer is convinced they need the power to be 110v for safety reasons.

I'm after some advice about what consumer units and breakers i will need for this.

The trailer will have:-

1 circuit for a 5way power block in the cabinet
1 circuit for 8 power sockets in dado trunking
1 circuit for an external waterproof socket

(The lights will be 12v straight off the battery)

I'm having trouble getting advice about this as 110v used in this way doesnt seem too common!!

Any advice will be gratefully recieved!

D

 

[plugwash]

I would use IEC connectors for the sockets inside the trailer, using BS1363 sockets for 110V seems to be asking for trouble and CEEFORMS are rather on the bulky side.

I would use a normal consumer unit with RCD but I would also check with the manufacturer that the RCD was suitable for 110V use.

You will probablly want a supply changeover switch and an external inlet to allow running the trailer off generator or site power.

 

[Spark123]

What sort of 110v? CTE / Earthed Neutral / Separate?

 

[ban-all-sheds]

the customer is convinced they need the power to be 110v for safety reasons.

Yup.

Electrocution by the 110-120V domestic electrical supply is unheard of in the USA...

I'm after some advice about what consumer units and breakers i will need for this.

110V breakers and 110V RCDs.

I would use IEC connectors for the sockets inside the trailer

Which sort?

 

[Chri5]

Construction site ?

See 704.1.1 (vii)

"The regulations for 110v in admin locations of construction sites DO NOT apply", the general requirements of Part 1-6 of 17th : 2008 do apply

So 230v and IT ADS system see 411.6 and if they insist on 110v 411.8

 

[Spark123]

IT as in Information technology or IT as in the ADS method of fault protection?

 

[Lectrician]

Pointless using 110v. No requirement at all.

 

[Lectrician]

As its an inverter, you need to be careful with fault protection.

 

[plugwash]

I would use IEC connectors for the sockets inside the trailer

Which sort?

IEC 320 series connectors, either the 10A ones used on PCs or the 16A variant commonly seen on larger UPS units.

 

[dullSpark]

Why ever invert the power from the batteries? Switch mode power supplies for computers run very well on DC if the voltage is over 90volts or so.

 

[plugwash]

serveral issues with using DC in ordinary PC PSUS.

firstly you really want to check out the power supplies first if doing that. If the manufacturer for some reason decides to stick and inductor accross the input it could be a near dead short at DC.

Secondly connectors, switches etc designed for AC may not operate safely with DC (DC is far more prone to arcing).

Thirdly you have to work out what to do about the monitors, all the same issues may apply there.

 

[SeanT]

Working for a firm that uses a lot of DC power, my only thought on that is not to attempt to wire something at that sort of voltage DC unless you know exactly what you are doing, and have the right switchgear etc. - as in comments above, the best way to do this, in the UK, is just to invert upto 240V AC and then wire it as you would normally, most probably with high integrity earthing - so much less hassle. Don't forget some surge protection too.

 

[dullSpark]

I realise the problems with switching DC and that it would be more hassle than inverting; but the added cost of inverters and the 20-30% extra lossage in the system, which will be output as heat which we have to get rid of, is a little to hard to ignore.

Monitors use SMPS also, in fact the only things that don't really are devices that run off 5-12vdc, could this not be run off a tapped battery?

Think of it really, DC>50hzAC>DC>25KhzAC>DC, with a 5-10% lossage at each stage, or DC>25KhzAC>DC?

 

[rizred]

Hi everybody

Thanks for the response

However i now have even more questions!!
(please bear in mind that i am not an electrician....)

Plugwash - i had assumed that i could use normal 3 pin sockets for the user ends - the customer needs to be able to plug any type of equipment in. Does the 110v require different sockets?

Spark123 - we have a sterling ProPower Q quasi sine wave inverter to output the 110v. i cant find any information that would answer you question about what sort of 110?

ban-all-sheds - can you recommend a source for 110v breakers and RCDs?

Chri5 - The trailer could be defined as a "mobile admin area" so can i assume that this would be classed in the same way as an "admin location of a construction site", and therefore need to adhere to the general requirements of 1-6 of 17th :2008, and 411.8?

Spark123 - IT as in information tech - the trailer will basically be a mobile office, with the usual mix of IT/ Office and communications equipment

Lectrician - what would you recommend for fault protection?

dullspark - we can't be sure exactly what equipment may be used in the trailer, so we need as standard a power solution as possible (within the customers 110v requirments)

Finally, what would the testing requirments be for an installation like this, and is it something any appropriatly qualified electrician can test and certify?

Thanks again for your time

D

 

[ban-all-sheds]

(please bear in mind that i am not an electrician....)

This trailer will be a place of work.

So the HASAW act will apply. The EAW regulations will apply.

And let's not forget that the Construction Design and Management Regulations 1994 impose a duty on your client to appoint competent designers.

You really should not be designing the power distribution circuits within this trailer.....